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| QUESTION NO. Sony TAN5550 amp. Looking for some replacement transistors for this old unit, the subs DO NOT have to be the SAME physical size as the originals because this is an older amp with a FAIR amount of space on the PCB (even for the outputs MOSFET's), I need the following subs 2SC1124 - 2SA835 - 2SC634A - 2SC926A - 2SA939S - 2SA671 - 2SA678 - 2SC1061 - 2SK58 (dual 2SK107 apparently) - 2SK60 - 2SJ18 The reason I am replacing ALL the transistors is that this old unit is making LOUD intermittent noises at any volume level, and with my previous experiences in the audio field repair business, I found out that when you have an amp with "strange" behavior like this one and also the fact that ALL semiconductors (except the outputs MOSFETS's) have that "blackening" of their leads, it's better to replace them ALL otherwise the ones that were NOT replaced will go out after a little while, and on this amp it's VERY EASY to do with all the room around the various parts. I am also replacing ALL electrolytics on the boards at the same time (there are not that many anyway). |
| Intermittent loud audio? Blackened leads on all semi's? Frankly, it would be good practice to do a comprehensive solder-up, with fresh solder & flux, in this situation, and just might solve the problem. But I suppose replacing all the components might accomplish this as well.... As far as replacement semiconductors go, it is best to use the original whenever obtainable, but if this is not feasible, you might try these suggestions. For 2SC1124, try NTE/ECG190, or 2SC3902. For 2SA835, try NTE/ECG288, 2SB648, or 2SB631K. For 2SC634A, try NTE/ECG85, 2SC1740S, or 2SC1815. For 2SC926A, try NTE/ECG154, or 2SC1921. For 2SA939S, try 2SA1210, 2SA1698, or 2SB718. For 2SA671, try NTE/ECG292, 2SA985, or 2SB941. For 2SA678, try NTE/ECG290A, 2SA933AS, or 2SA953. For 2SC1061, try NTE/ECG152, 2SD526, or 2SD1135. For 2SK58, try NTE/ECG461, or U441. The 2SK60 and 2SJ18 are a unique set of complementary N-type and P-type power JFET transistors (170 Volt, 5 Amp, 63 Watt). I know of no substitutes; this role is nowadays filled by power MOSFET's (enhancement-mode devices), instead of JFET's (depletion-mode devices). Sources for originals could include B&D (www.bdent.com) or Dalbani (www.dalbani.com). Distributors for NTE & ECG devices can be located from the websites for NTE (www.nteinc.com) and ECG (www.ecgproducts.com). |
| QUESTION NO. P122-10: Motorola Mocom 10 2 way radio. Need a cross reference for the transmitter final output A M9553 transistor. |
| Since the days of the Mocom are long gone and Motorola only complicated the matters by totally changing their inventory/part numbering totally around, this can be difficult. If you have a manual and can obtain the original part number you can call Motorola direct and get a crossed part from them. Their parts phone number is on their site. You might also try batlabs.com. This is a great site for Motorola owners! ECG electronics has a RF selector guide if you know what parameters you are looking for to replace this final with. |
| Try <http//www.rfparts.com/>. Chances are that they have a cross reference number for you, as well as the part. |
| QUESTION NO. P117-8: Sony CCD-FX411 camcorder, plays fine as VCR most of time, but when used as camera, usually displays the "no tape" icon. Tape door not damaged, loads and unloads easily, and will eventually record tapes in CAMERA position if tape is ejected and reloaded once or twice. Have cleaned sensor and on/off switches, seemed to help. |
| Try replacing the tape detect switch on the chassis. Also check for a break in the chassis flex, or try cleaning and applying Sony's grease to the three connectors on the bottom mech. board. I have also seen bad solders to these connectors, and on the main board cause this. |
| QUESTION NO. P1213-2: Sony PS-X55 turntable. Trying to cross-ref a NLA motor for tonearm lift/pivot for this 1980 unit. Sony lists the motor as their 154-116-500 but no longer available and no cross-ref. What I'm getting is good torque driving forward (arm lift/return) and poor torque on reverse polarity (arm drop/set). I'd like to find something I can cross-ref in there with similar shaft sizing. |
| If you are going to repair this unit with parts no longer available, cClean out the "old" lubricant then lubricate with high quality "non-wicking" grease. This will require some disassembly. A single drop of high quality oil on the turntable shaft. Do Not Over Lubricate. |
| QUESTION NO. P110-10: Sharp BA-1600 amp was overloaded and now it displays "Protect". |
| This usually indicates that one or more output stages are either blown, shorted, or fried. Do not try to override the "Protect" stage. This is protecting the power supply from extensive damage. Replace the Amp IC, or transistors. |
| QUESTION NO. P1214-6: Chrysler CD/cassette player. CD's will not load, everything else works fine. I cleaned the lenses and reflectors but cd's are not sensed and will not load. A CD placed in the unit will eject so the motor is working. |
| If you can put CD's in, but they will not play, (I assume that is the problem), the optical pickup is defective. Available at MCM Electronics. |
| QUESTION NO. P111-7: RCA DRD221RD dss receiver. I need a cross reference on Q14110 (TO220 package) one number is K2862 and in another receiver (same component reference) it has several markings which include W926moroccoP4NB50 FP,or P4N850FP. |
| 2SK2862 is a Toshiba Mosfet, rated 500 Volt, 3 Amp, and STP4NB50FP is a ST Micro Mosfet, rated 500 Volt, 2.5 Amp. Similar devices include 2SK2182, 2SK1245, 2SK3045, and IRFI820. B&D (www.bdent.com) is listing 2SK2182 and 2SK1245, and Digikey (www.digikey.com) is listing 2SK3045. Newark (www.newark.com) is listing IRFI830, a beefier device than IRFI820. If insulation hardware can be provided, plain IRF820 or IRF830 could be tried. |
| QUESTION NO. P1218-7: Sony FM Stereo/FM-AM Receiver Model STR-GX909ES, the center speaker does not work. Also, when turned on, the prompt" Protector flashes." |
| I have worked on a different model Sony receiver that has flashed 'Protector' in the past. This indicated that one or more of the power output stages is fried. If left/right channels work, check the center amplifier. |
| QUESTION NO. P1120-6: I have a surround sound processor which decodes a mono surround signal from a stereo Source (DVD movie or an audio CD). The problem is that there is a dialogue leakage into the surround speakers which is not supposed to be there and hence is very annoying but when I played the same movie on a prologic amplifier there was no leakage in the surround speakers. Is the problem due to unbalanced input signals? The surround decoder is a simple one and it does balances the input signals before processing them unlike a prologic decoder which balances the inputs. When I connected a same that is a mono signal to both the inputs of the decoder, it did not produce any dialogue leakage but only a little amount of high frequency voice and music which I think is due to the inability of the processor to cancel out high frequency signal. |
| A pro-logic decoder uses an analog matrix to send the sound in the proper speakers. The sound fed to the surround speakers is a mono signal that is processed using a anti-alias filter, an audio delay, 7khz low-pass filter and then a modified B-type Dolby NR decoder. This gives out a signal without much high frequencies and without much low frequencies in most cases because the receiver usually will reroute the bass information to the main or the sub speaker. Regarding the balance control, all pro-logic decoder MUST have such a circuit. It is either a manual adjustment or a circuit that does it automatically, but it must be there for the unit to have the Dolby Pro-logic logo. This information also applies to Dolby Surround speakers, as the only difference is the stearing mechanism that allows it to have a real center channel. If your decoder leaks dialog in the surround speakers, the balance control is certainly to suspect as this is the first sign of an incorrect balance setting. As for the high frequencies in the surround speakers, anything above 7Khz should not be there. Unless this unit is very old, most decoders now stand on a single chip. If it is a little older, you may have a pro-logic matrix decoder chip (LA2770) and a few other chips for the different circuits I listed above, in which case some troubleshooting may solve your problem. |
| QUESTION NO. P1128-5: Onkyo amplifier TX-108 works great when first turned on and for about 3 minutes before it starts drawing an immense amout of current, blows the input fuse and takes out the channel output transistors. It will do this for which ever channel is selected by the speaker selection switch (A,B or A/B). I replaced the output transistors but this does not fix the problem. I have the Sams photo-fact for this unit but the data is not very helpful. |
| Consider the BIAS transistor as a potential culprit. This device is usually mounted on the same heat sink as the O/P devices, and adjusts the bias to thermally stabilise them. If this device fails open, the output will usually swing to 100% of one of the power rails, and depending on the circuit topography, the result can be quite destructive. Check the device by substitution, or try tapping the heat sink as soon as the unit comes out of power up delay. Do this without any applied load, as this may minimize the damage to the expensive outputs. |
| QUESTION NO. P1130-3: I shorted a speaker connection and the Pioneer sx 780 blew and continues to blow the 4a fuse on its fuse board when power is turned on. The power is all dead. |
| This unit is a vintage receiver/amp and after carefully continuing searching for a short, advice given by an online response, kept looking for one. The rectifier bridge was checked first by voltmeter at its output leads and reported voltage, the two Darlington Stk0050 power pack IC's showed identical ohm readings between their terminals, except one had 0 ohm between terminals #8 and #9. This part was removed from the board, 4a fuse replaced and unit powered up. #8 and #9 remained shorted off the board. The 50 watt part was found locally for $15 and mounted with a refresh of the heat conducting gel to its heat sinks. The cross ref. for the stk0050 is NTE1281 and also ECG1281. |
| QUESTION NO. P1128-4: Carver amplifiers part #s PMA-2062 and PMA-2150. I cannot find any service literature or parts houses who might carry this line of data. |
| Carver corp is in recievership, there are a group of former employees providing service etc. Try www.carveraudio.com. |
| QUESTION NO. P1122-1: Sony ICF2001D receiver. I need a sub for Q303 (transistor SK152). |
| This is the same as ICF-2010. The 2SK152 can be replaced by an MPF-102. For more detailed info go to http//members.home.net/snarayan/misc/sw/q303_board.html. |
| QUESTION NO. P1031-2: JVC Modrx-517vtn audio equipment. Fuse blows when on button pressed. I found two of the output transistors shorted, part numbers A1633 and C4278. I need a source and cross reference info. |
| 2SA1633 and 2SC4278, from Rohm, are complementary PNP and NPN audio power transistors, rated 150 Volts, 10 Amps, 100 Watts. They are fairly easy to source, for Audio Lab of Georgia (audiolab.home.mindspring.com), B&D Enterprises (www.bdent.com), Dalbani Corp. (www.dalbani.com), MCM (www.mcmelectronics.com), & Union Electronics (ued.net/index.html), among others, all list them on-line. |
| QUESTION NO. P1026-5: Compact xl-gm800tn disc graphic changer player. I need to know specific functions of ic601 (cxa1372s) and ic271 (m66007p). Machine will load disc but it will not spin. |
| CXA1372 is from Sony, and it is a CD-player Servo Amp IC. M66007P is from Mitsubishi, and it is a 12-bit, parallel input->serial output, shift register IC. |
| Before you get too involved in troubleshooting this, did you know that if the laser is dead (or nearly so) the player will not spin up the CD? I have worked on many of these units, and so far a bad laser has been the only cause of this particular problem. |
| QUESTION NO. P1023-8: I am looking for an audio output chip for an approx. 15-year-old Marantz tuner. It is Part STK0050 Mark II (or STK0060 Mark II will work). Apparently, this part is manufactured by Sony. I have searched out and contacted several Canada and US Sony and Marantz dealers/service rep. - to no avail. |
| STK devices are Sanyo, not Sony. Try Dalbani (800-325-2264; www.dalbani.com) or Union Electronics (800-648-6657; http//ued.net/index.html) for STK0050-II. |
| QUESTION NO. P105-5: Pioneer receiver sx-780 came with two darlington power packs model # stk-0050. This part has been discontinued, I need a source or a substitute. |
| The sub for stk0050 is ecg1281, nte1281. |
| QUESTION NO. P1018-11: Pioneer m-770 power amp module. I replaced q7111, q7112, ic7404. The problem is that I have 63 volts only on main speaker terminals but cannot find any more shorted parts or bad resistors. Tested surface mount ic op amps with diode test on meter, they seem ok. |
| I replaced q7111 [ecg152], q7112 [ecg153], ic7404 [7805], and q7104 [npn], q7110 [pnp] both surface mount. Also replaced ic481 [upc4570c] in cx770 volume control board. |
| In the radio [cx770] I replaced Lm7001 [ic6202] pll, upc4570c [ic402,ic481], upc4558 [ic431, ic432], ta8409 [ic403]. In the amp [m770] I replaced 2sd1006[q7104], 2sb798[q7110], 7805 [ic7404], 1n4148 [d309], ecg153mcp[q71111, q7112], [2] t4amp,t6.3amp. |
| QUESTION NO. P104-9: I need a source for a motorola chip NC1307 used in a Scott, tuner amp model 636 am fm approx (1972) (I tried the Scott site). |
| If this is a Motorola IC, I suspect it is a MC1307, and substitutes for that chip are ECG 722, or NTE 722. The .PDF datasheet for NTE722 might confirm this, it is found at www.nteinc.com/specs/700to799/pdf/nte722.pdf Mouser Electronics (800-346-6873; www.mouser.com) lists NTE722 in their current catalog. |
| QUESTION NO. P102-9: Looking for a replacement IC for a burnt out MB3712 froma GE CB radio. ECG lists a replacement as a 1423 (discontinued) & a 1424 (also discontinued), MCM electronics claims to have a replacement but when ordered was told it was discontinued. I believe it to be a Fairchild IC but have received no response form the company. Here is all the information I have on the replacement ECG1424 8-pin SIP-HS, IC-AF PO, 5.7W, Vcc=13.2C, Rl=4 Ohms. Any help in locating an MB3712, and ECG 1423 or 1424 or any equivalent from any manufacturer would be most appreciated. |
| I believe MB3712 is a Fujitsu IC, not from Fairchild. Try Dalbani (800-325-2264; www.dalbani.com) or Union Electronics (800-648-6657; ued.net/index.html) for this MB3712 IC. Mouser Electronics (800-346-6873; www.mouser.com) and Audio Lab of Georgia (800-554-9248; audiolab.home.mindspring.com) are still listing NTE1424, as well. |
| QUESTION NO. P926-7: I need replacement parts for a Delco/Bose audio amplifier, part # 16148748. Specifically STMicroelectronics P/N 137110 transistor, bose IC # 131354 88944 and bose IC # 134499 88945. I have searched for all of these parts, but so far haven't found any information on availability, pinouts, etc. |
| Bose does not sell parts,or offer any technical help. They require that the unit be sent to them for repair. I have just been through this with an AW-1 wave radio. Just had to return unit to customer unfixed. |
| I too ran across this problem while trying to repair a set of rear amplified speakers from a Nissan Maxima. I tried Bose who sent me to Clarion who sent me to Nissan who sent me to etc..... Anyway one of the speakers had been repaired before and they used after market parts for the Bose output transistors 137110 the substitute part was a IRFZ-44 or cross to ECG-2395. |
| QUESTION NO. P929-8: Technics SU-Z780 amp. Line in was overloaded by TV audio out. Amp works but when volume is turned up, sound cuts out. Also, now has bleedover from different components (i.e. can hear tuner when listening to tape). |
| I have seen many Technics receivers with the second problem you described. Check the positive and negative 15 volt power supplies, usually a transistor or two will fail there (normally located near the output I.C.s), or a resistor may be burnt near your switching I.C.(s). Also,the switching IC itself could be bad. This IC is located on the main board near the input jacks (typically a TC 91xx number). This IC is a good place to check for your +/- 15 volts,by the way. Chances are,one of the above is your problem. You will probably need to remove the circuit boards from the metal chassis,in order to gain access to the solder side of the main board. Newer receivers can be very time-consuming to repair because of the lack of an access plate on the bottom. |
| QUESTION NO. P926-3: I need a source for STK4152II power amplifier module. |
| The original STK4152II is listed by B&D Enterprises (800-458-6053; www.bdent.com) and Dalbani Corp. (800-325-2264; www.dalbani.com); ECG or NTE 1819 is also listed as a substitute. |
| QUESTION NO. P912-3: Need pin-out diagram for a Pioneer STK 4171 II power amplifier module. |
| Pin#1 = Left channel input (-); Pin#2 = Left channel input (+); Pins#3, 4, 5, 7, 8, 15 = Compensation; Pin# 6 = Muting; Pin# 9 = -Vcc; Pin# 10 = Left channel Output; Pin#11 = +Vcc; Pin#12 = Bypass; Pin#13 = Right channel output; Pin#14 = -Vcc; Pin#16 = Gnd; Pin#17 = Right channel input (+); Pin#18 = Right channel input (-). Or, for circuit diagram representations, see the two diagrams in the PDF located at www.bdent.com/schematics/STK4172II.PDF (similar enough for this purpose). |
| QUESTION NO. P830-1: Hafler amp . I need the replacement for two 2sj49 cmoss transistors which are part of the right side final outputs. |
| Because Hitachi's 2SJ49 has an unusual pinout configuration, is best to try to get the original 2SJ49; try Dalbani Corp. (800-325-2264; www.dalbani.com) or Union Electronics (800-648-6657; ued.net/index.html). |
| QUESTION NO. P726-3: Aiwa bookshelf stereo CXna303 works fine but display is no longer visible. |
| How are your backlight lamps? I repaired a Aiwa stereo display by installing new lamps. Customer was happy that it worked but not about the bill. OEM lamps can be expensive. |
| QUESTION NO. P88-6: Aiwa CX-NMT920 CD spins for about 10 seconds and it will change to the next and do the same thing. I replaced the optical assembly, no change. All flat cables are OK. |
| Possible that you have the same problem and fix as in FAQ's Audio section questions with answers. Check out Q&A P611-4 but mostly pay close attention to Q&A P64-2. |
| QUESTION NO. P78-7: Sansui integerated amplifier. I need a source for transistors 2sc260 (EIC) and 2sa981(SANKEN) both on the main board. |
| Replacement for 2sc260 = 2sc756-2 or 2sc524 or 2sc822. Replacement for 2sa981= 2sb816 or 2sb681 or 2sb849 or 2sa1072. 2sb816 is match pair with 2sd1046. 2sb681 is match pair with 2sd551. 2sb849 is match pair with 2sd1110. 2sa1072 is match pair with 2sc2522. |
| QUESTION NO. P89-7: Kenwood KAC-818 power amplifier. I need a substitute for the input transistor with case stamping of MTAJ50N05HDLFK |
| Digikey (800-344-4539; www.digikey.com) is listing IRF's IRLIZ44N and Toshiba's 2SK2312 in their catalog. |
| QUESTION NO. P721-9: Pioneer VSX-5300 Receiver works for approximately 30 minutes and then begins changing modes on it's on and turns itself off. |
| You may have a loose ground problem. Try tightening down all screws that you can find that hold the circuit boards to the frame. The boards are common grounded and the frame is the key in many of these amps. |
| Your answer is a good one. However, in many Pioneer receivers/amps, they used a GC Bond type of glue on the circuit board, which hardened with age. It then became "semiconductive" in nature. I have had to remove it any time I found it. Causes major headaches and "unsolvable" symptoms. |
| QUESTION NO. P77-5: Realistic 2600, left channel has a crackling noise on cold start and stops after 2 to 5 minutes. There is a floating voltage of 0.9vdc to 1.1vdc at the base pin of npn output x'sistor and voltage at base pin of pnp output is .0045mvdc and they are should be .5vdc to .6vdc compared to the voltages on the right channel. Also tuner display is flashing when it is in cd/aux input. |
| For the crackling noise try a little cold spray on the transistors, caps in the final amp circuit after it has warmed up and stopped crackling. I have found many odd problems this way. |
| There might also be a bad solder joint causing some of the trouble too. Use the can of cold shot to check the solder joints around the output transistors, and their drivers. |
| QUESTION NO. P81-9: I need the equivelent of D895 output transistor for a JVC R-1X Stereo Receiver. |
| D895 is a 2SD895 and is available from MAT Electronics 1-800-628-1005. |
| d895 =2sd895 cross to n t e 36 p n p power amp switch. |
| QUESTION NO. P628-3: Where can I get a replacement for a TA2040 and a TA2030 ic set out of a Kenwood Basic M1A power amp? MCM does not list it neither does the NTE cross reference book. I have a good schematic and on the TA2040 the base to collector pins 11 and 21 are shorted and pins 22 to 19 have low ohms reading compared to the good channel. TA2030 is the DLD hi/low switcher and reads differently on pins 14 to 16 from the good channel. I suspect there may be a cross reference for these to a more readily available ic part # but cannot find any cross reference info on them. |
| TA2040 is listed at Mat Electronics for $49.95. They have no listing on the TA2030. Ph 1-800-628-1118 US & Canada. 1-800-811-5177 West Coast only. EMAILsales@matelectronics.com. |
| QUESTION NO. P628-10: I need a datasheet or pinout of Pioneer car radio audio driver HA 13155. |
| The datasheet for HA13155 can be downloaded from Hitachi's website, at www.hitachi.co.jp/Sicd/English/Products/senyou/eHA13155.pdf as a PDF document. |
| QUESTION NO. P526-7: I need a source or sub for STK 3106 amplifier for a Sansui 7000. |
| Fox International Ltd., Inc. 23600 Aurora Road, Bedford Heights, Ohio 44146-1712 phone 800-321-6993. |
| QUESTION NO. P69-3: I need a source a KA2265 IC used in the FM stage of the radio section of the amp. It is a Samsung component and Samsung are not able to supply the part nor the maker [Sherwood]of the AMP. |
| Try Union Electronics (800-648-6657; http//ued.net/index.html); or B B & W, Inc. (800-749-1710; www.bbwelectronics.com) for KA2265. |
| QUESTION NO. P68-8: I need a replacement for P50N06= power mosfet= ECG?? or other and C2592 =dual diode in a TO-220 case=?? out of a Car Audio Amps switching power supply. |
| P50N06 describes a 60 Volt, 50 Amp MOSFET, so the ECG would be ECG2395. You could also use STP50N06, listed by Mouser Electronics (800-346-6873; www.mouser.com). A C2592, in a TO220 case, would describe Matsushita's transistor 2SC2592, so double-check your part. 2SC2592 is rated 180 Volts, 1 Amp, 20 Watt, 200 MHz, 30 pF, gain 90-330. A possible sub for 2SC2592, might be 2SC2336, which is also listed by Mouser Electronics. |
| QUESTION NO. P65-8: Need to know if the HA-13158 Hitachi amp requires -12VDC. Pinout/datasheet would help. |
| There is no "requirement" for a -12VDC supply; HA13158A is a single-supply IC, Vcc is nominally +13.2V, referencing to common. The datasheet is available at www.bdent.com/schematics/HA13158A.pdf and it has the pin descriptions. |
| QUESTION NO. P512-10: Need two ICs for a Panasonic portable cassette player, both being surface mounted devices: AN6612S - dc motor regulator (8 pin) and LA4571M - low power preamp/amp (20 pin). Who makes these ICs and where can I find the datasheets? Are there any cross-reference parts I can use? |
| AN6612S is a Panasonic IC, datasheet at www.mec.panasonic.co.jp/sc/e-data/L60/S06/AN6612.pdf. LA4571M is a Sanyo IC, datasheet at www.elisnet.or.jp/download/000/LA4571MB_1-10_10.pdf , or else try www.bdent.com/schematics/LA4571MB.PDF Crosses are unlikely; however, Union Electronics (800-648-6657; http//ued.net/index.html) is listing both the original IC's. |
| QUESTION NO. P419-4: I need to replace some mosfets in an Orion car amp. I do not know who the manufacturer is and cannot seem to cross it to an equivalent. The part number is SMW60N06-18. Should be a N channel. |
| SMW60N06-18 was made by Siliconix, back before they focused on surface mount MOSFETs. It is a 60 Volt, 60 Amp, 105 Watt N-FET, Rds[on] <0.018 ohm @ 30 Amps. An equivalent is IRFP048 (IRFP054 may also work); try Newark Electronics (800-463-9275; www.newark.com) or Digikey (800-344-4539; www.digikey.com). The NTE replacement# NTE2920 is another possibility. |
| QUESTION NO. P414-3: Looking for equivalent power transistors for Sony amplifier. Sony part number is MN2488-OPY-M and MP1620-OPY-M. Any idea of what these transistors really are? |
| Sanken made your devices (discontinued). They also made 2SD2488 and 2SB1620, which may be the same, or similar. These industry-numbered devices are a complementary pair (NPN and PNP) of 200 Volt, 15 Amp power Darlingtons, packaged in a wide MT100 case, with two mounting holes, one on each side. So see if these use the same package, as your OEM transistors. Audio Lab of Georgia (800-554-9248; audiolab.home.mindspring.com); B&D Enterprises (800-458-6053; www.bdent.com), and MCM Electronics (800-543-4330; www.mcmelectronics.com) list the Sanken devices. By the way, Audio Lab's website also lists the MN2488 itself, for twice the price of their 2SD2488, though they also indicate a cross to 2SD2488. |
| Transistors mn2488 & mp1620 are Darlington IC'c, npn & pnp respectively. They are power outputs, available from Fox International approximately $36 for the pair. |
| I ordered MN2488-OPY-M and MP1620-OPY-M transistors from Sony and got 2SD2488 and 2SB1620 as substitutes. |
| QUESTION NO. P411-10: I need info on IC402 in 1989 JVC RX-302BK stereo receiver. It is marked 1281 or I2BI on top and 9.8 P on bottom. It is in a 3 lead TO92 housing mounted near the digital display. |
| IC402 is a reset IC. Pin 1 drives digital transistors Q403 (and Q402, via 403), which drive Q401 and ultimately pin 19 on IC401. The generic part number for this IC is MN1281. JVC's part number on the IC is MN1281(P,Q). |
| QUESTION NO. P46-4: I need to cross reference a transistor, 2SA527. It is out of an old Sony receiver. |
| 2sa527 cross to nte 129 pnp si af output to 39. |
| QUESTION NO. P211-8: Aiwa nsx-v70 mini hifi display is very dim and is hardly readable. |
| Check caps in series to AC voltage for display illumination (before it is converted to -VL). They should be 10mF/50V. |
| QUESTION NO. P225-2: Technics SA-GX290 Receiver, when powering up the receiver, "speaker overload" or "overload" appears immediately after the inital power up relay kicks in. It seems to be four output transistors, I removed the one that I suspected bad. Should I power up the receiver after removing one at a time to try an isolate the failed part, or would this be unwise and cause more damage OR give me false indications? |
| More then likely the outputs are shorted. Probably just one channel is shorted. Are there 4 xistors per channel or just 4 output xistors? No matter. Just take your DIGITAL multimeter and check front, back ratio on all 4 xistors. I mean Btoe btoc. base to emitter base to collector. One xistor is npn the other is pnp. Try not to do your method. |
| QUESTION NO. P31-4: Kenwood Kac-823 car amp - need replacement for Q33, part number K1190. |
| This sounds like a Sanken 2SK1190 MOSFET, rated 60 Volts, 22 Amp, 35 Watt. MCM (800-543-4330; www.mcmelectronics.com) lists 2SK1190 for $8.65, but an IRFIZ34E is an equivalent type, and Digikey (800-344-4539; www.digikey.com) lists the IRFIZ34E for $1.49. |
| QUESTION NO. P124-2: CCD3610 (firmware 3.01) CD recorder passes all the self-testing, adaptec program test, test before writing. The problem at the end of a writing process, closes the cd instantly, so the TOC is not writed. System bios, hardware and software are tested o.k. (no change was made). I also tried another firmware like 3.09, and DMA. |
| Must be a Phillips. Check this web site http://www.rict.freeserve.co.uk/. |
| QUESTION NO. P217-8: Pioneer 3SX-VO5 stereo with blown output transistors by Toshiba (C5198 & A1941) which I cannot find anywhere. What substitutes, if any, are available? |
| Transistors 2SC5198 and 2SA1941 are listed by MCM Electronics (800-543-4330; www.mcmelectronics.com), Audio Lab of Georgia (800-554-9248; audiolab.home.mindspring.com), and B&D Enterprises (800-458-6053; www.bdent.com), among others. If you need other substitutes, the pair 2SC4468 and 2SA1695, or else the universal sub complementary pair ECG/NTE 36 (NPN) and 37 (PNP), will be similar devices. |
| QUESTION NO. P215-3: Kenwood ka-3500 Integrated amplifier has blown its output and driver transistors. They appear to be NEC devices. The output devices are marked B618 and D588. These appear to have their emitter and base pins reversed compared to a standard TO220 or TOP-3 type package. The others A733 and A721 are small signal type transistors. |
| NEC are Japanese transistors. Most Japanese transistors start with the prefix 2S. This is not usually printed on the device. So Bxxx becomes 2SBxxx, etc. |
| Union Electronic Distributors (800-648-6657, website at ued.net/index.html) is listing all four transistors in its inventory, 2SA721, 2SA733, 2SB618, and 2SD588. |
| QUESTION NO. P21-7: Sansui AU2900 amplifier. Where can I find information for IC A798 (5-pin)? |
| That "A798" is not an IC, it is a dual PNP transistor, with emitters in common. The full number is 2SA798, and pinout is B1, C1, E, C2, B2. The transistors are rated 50 Volts, 0.1 Amp, 0.2 Watt, 250-800 gain, with low noise-factor. These devices are generally used as low-level, low-noise differential amplifiers. |
| QUESTION NO. P112-7: I think I need to replace the STK 2048 II in a Technics amplifier. I have been searching for technical documentation on this STK, but cannot find anything. |
| I see a listing for stk 204811 in Dalbani's catalog. It is made by Sanyo and costs $15.67. According to my book. their phone # is 800-325-2264. |
| QUESTION NO. P124-7: I am restoring a stereo amplifier which was made in the U.K. in the late 60's. The amp in question uses RCA 39251 power transistors and I am unable to obtain any data on them. As a few have "blown" and I need to replace them with a modern day equivilent, as I do not think that originals are still available. Do you know of a suitable replacement? |
| As per ECG Semiconductors Master Replacement Guide, the RCA PN 39251 is ECG130. Description NPN-SI, AF Pwr Amp. Vcb100v, Vce60v, Veb7v, Ic15Amp, Pd115Watt, Ft0.800Mhz, hfe40 typ, caseTO-3. (Exp 2SD172,2SD173....2SC1667....). |
| ECG and NTE both cross a 39251 to their type 130 transistors, TO-3 case, NPN, 100 Vcbo, 60 Vceo, 15 Amp, 115 Watt. If your geographic location does not permit obtaining ECG or NTE parts, those ratings correspond to the common 2N3055 or 2N3055A power transistors. |
| QUESTION NO. P120-10: Need a replacement for 2SB557 and 2SD427 for a Sherwood Stereo Receiver. Schematic list alternates as 2SD388A2 and 2SB541A2. |
| Union Electronics Dist. (800-648-6657; www.unionel.com) lists all four transistors in their online inventory; MCM (800-543-4330; www.mcmelectronics.com) lists both 2SB557 & 2SD427. |
| QUESTION NO. P118-7: Mitsubishi DAR24 stero receiver that has shut down. I need a source for part STK 1060II. |
| These suppliers (among others) are listing STK1060II in their stock. B&D Enterprises (800-458-6053; www.bdent.com); Union Electronics Dist.(800-648-6657; www.unionel.com); MCM (800-543-4330; www.mcmelectronics.com); Audio Lab of Georgia (800-554-9248; audiolab.home.mindspring.com). |
| QUESTION NO. P126-7: Carvin X-60B guitar amplifier that has two very fried resistors. I need the values of R114 and R115. I assume the tubes caused these resistors to fry, so I have changed both output tubes. Could something else have caused this? |
| R114, 113, 115, 116 are Screen resistors. They were originally 22 ohm 1/2 watts but were later changed to 350 Ohm 5 Watts. Typically bad output tubes can cause these to burn up but not always. Do the upgrade and you should be fine. |
| When you are replacing those resistors, you should go to higher wattage, whether you go to the higher resistance or not. You will have a slight difference in gain when you change the value of the resistance of those 2 resistors. I believe if you check the tube pinout, R114, and 115 should go to the cathode. These carry all of the current that goes out to the output transformer. The old resistors may have simply failed as a result of the excess current they carried. Your old tubes might be just fine- just test them to make sure they are not gassy, because that increases current flow through the tube. |
| QUESTION NO. P1222-1: Pioneer KEH-1550 audio equipment had a blown output transistor due to wrong connections, with blown values, I can read partialy ???7D2 - ?A13155. Where can I find one of these? I am in Brazil so anything over the web would be nice. |
| The transistor is HA13155, the top number is for manufacturer information only. The unit is working fine with the right connections and the new transistor. |
| QUESTION NO. P129-9: Aiwa cx n340k, audio is ok on all functions until t bass is selected, then a loud bass left/right phasing occurs which is unaffected by volume control change. |
| Probably the T-Bass IC has failed. It is a surface mounted IC on the front panel PCB. |
| QUESTION NO. P1216-6: I need a replacement for Q5 in a Kenwood KAC-524 car amp. It is in a tall TO-92 case with the markings A817A. |
| Use NTE298 - http//www.nteinc.com/specs/200to299/NTE297.html. For a distributor try http//www.nteinc.com/NET_St_lst/Disty.html. |
| That is a Toshiba 2SA817A, PNP transistor, rated 80 Volt, 0.4 Amp, 0.8 Watt. B&D Enterprises (800-458-6053; www.bdent.com) lists it for $1.59. Or you could substitute an ECG/NTE 298 transistor. |
| QUESTION NO. P119-10: Coustic Power Logic amp 360 car amp will not power up. The ground connection is good and there is the correct voltage on the upstream side of the thermal fuse. |
| Check control i.c. I think it is a upc494 or 595. Make sure you have 12 volts going to the i.c. Also, make sure you have a square wave going to the f.e.t.'s in the power supply, which comes from the control i.c. Make sure the f.e.t.'s are good & no dead short on the output transistors. |
| QUESTION NO. P1014-4: Marantz 2270 stereo receiver with distortion occurring in the left channel when the volume is set around 10 o'clock or more. The dc bias and ac balance can be adjusted to spec (5mvdc, 0vdc), the output transistors have been swapped with the "good" right channel amp, the speaker protection relay and speaker on/off switch has been bypassed. The left channel sounds weak and distorted compared with the right channel and I cannot detect it with a scope and dummy loads, only with a set of speakers and listening. |
| The problem was one of four things, R791 (2.2ohm/1w), R790 (10ohm/2w), C762 (.1uf/200v), or a bad solder connection. These three parts were swapped with the good channel and the distortion cleared up. As a precaution, the three original good components were replaced as well. |
| QUESTION NO. P105-3: Yamaha RX-330. When *not* using 'CD Direct', the sound starts making crackling noise and slowly starts to become more and more quiet. Switching the INPUT knob back and forth helps for about 30 minutes. |
| Replace input selector with new & improved Yamaha replacement selector switch with gold contacts. I do not have new part #. |
| QUESTION NO. P107-1: Pioneer car amplifier GM-X702, unit powers up and outputs when the input gain is very low, when I attempt to raise the gain the amplifier cuts in and out (can hear the relay open and close). I think it may be the output transistors. |
| Replace the pulse-width modulator 14-18 pin DIP. The part numbers vary so therefore I cannot provide you with one. The ECG cross reference book is a must in this application. |
| QUESTION NO. P1013-1: Pioneer GMX-404 car amp has no output. Power supply voltages +- 36vok. Op amp i.c voltages ok +-15v. There is a ta8194z i.c that seems to control muting of all 4 channels. DC checks show no d.c on any of the output channels and all transistors read good. |
| Toshiba's TA8194Z is intended to only mute transiently, during Power On/Off. If there is a continuous mute signal on pin#3, check if there is over 0.8 Volts Input activating either the Manual-mute pin (pin#6) or the Protection pin (pin#9), (pin#8 is ground), or if the cap at pin#5 has shorted out. For deeper inquiry, get the datasheet from doc.semicon.toshiba.co.jp/pdf_e/docweb123/e003731.pdf and use the Timing Diagrams and Operating Description to troubleshoot further. |
| QUESTION NO. P106-8: CT-FX718 car stereo. When any control key is pressed, a buzzing noise is heard. It traces back to Tuner section and occurs only in FM mode. Tuner, ucom checked OK. |
| Problem solved. Replace C205,0,047F-5,5V/5V to uom. |
| QUESTION NO. P914-1: Fisher receiver in need of ic stk4171V 22 pins. ecg has a listing but this is 18 pins. |
| Sanyo's own datasheet for STK4171V shows this IC as an 18-pin SIP. Are you sure yours is not an STK4171X? That one does have 22 pins. You may wish to get both datasheets from website www.elisnet.or.jp/login-sanyo.htm and see whether one or the other IC is the correct pinout. MCM (800-543-4330) does list two entries for STK4171V in its inventory, one of which is specified as "18 pins", so you might also inquire whether that means their other (unspecified) STK4171V entry has the 22 pins. |
| QUESTION NO. P99-3: Pioneer stereo SX-1100. It keeps blowing fuses. There is one part that shows mostly shorted but I cannot see what part it is, I only have a part number (4D4B44). |
| Usually, any stereo amp/receiver that blows fuses has shorted power output transistors. (These are the large transistors on the heat sink). If one pair is blown, check the driver transistors for them, and associated resistors. Be careful to get everything, because if you miss one defective component, you could blow the whole mess again! |
| The part you are referring to (4D4B44) is a bridge rectifier. I would say it's a 4-6 amp size and a general bridge rectifier will do the same job. |
| QUESTION NO. P817-8: Pioneer Receiver VSX-D603S. No Tuner reception on either band. Numbers change like normal but no audio. All other functions seem normal. |
| The LM7001 ic is a good candidate for this problem. |
| QUESTION NO. P817-1: Pioneer sa9500 stereo. Loud distorted noise after unit heats up. Preamp side of amp works fine as power amp side continues to turn on and off via the circuit breaker. |
| This is usually caused by a noisy transistor on the power amp board. I usualy pull them and curve trace them. Sometimes you can hit them with freeze spray and get immediate reactions also. It is usually a to-92 style transistor, not the bigger to-220. I do not have specifics because I have seen this problem several times and it is not always the same transistor. |
| QUESTION NO. P818-9: Bogan amp.cts-1060. Looking for a replacement or dirr\ect replacement for an ic SSM2015. This is a 14-pin ic and Bogan says they are no longer available. Analog Devices also say the same thing. Analog Devices sent me a replacement ssm2166s which is a surface mount device and cannot be usted on this amp. |
| It appears Analog Devices sent you the wrong type, because SSM2166P is the DIP form of that IC, while SSM2166S is the surface-mount IC. Newark Electronics (800-463-9275) is listing SSM2166P as being in their inventory, $4.29. But if the rep at A.D. made that kind of error, I'd be suspicious, so you may want to download the SSM2166 datasheet from Analog's website, www.analog.com , and doublecheck that SSM2166P has a pinout that will allow it to be a *drop-in* replacement for your IC. |
| QUESTION NO. P812-10: I need a supplier or sub for chip STK4141V for stereo amplifier chip (ouput)in stereo JVC set DRE2L. |
| STK4141V is listed by B&D Enterprises (800-458-6053), Union Electronic Distributors (800-648-6657), & MCM Electronics (800-543-4330), in order of increasing unit price. |
| QUESTION NO. P611-4: Jensen JX327 stereo system works fine except that the CDs will not play. It will start to spin and then it will stop and place the CD back into its holder. It has a seven disc CD holder, which keeps the CDs inside. I am able to retreive and place CD's into the holder, but cannot get them to play. |
| You may need to know that in order for the cd to play, several things must happen in sequence. First, the disc must spin. (You said it did). Then, the optical assy. must mechanically focus on the surface of the disc so as to be able to obtain digital data (pits and lands) and 'steer' the optical assy. along the track. You can usually see the mechanical motion of the lens as it tries to focus. it will go up and down several times while attempting to focus. Is that happening? If it cannot focus, the unit will most likely do what you describe. After focus is achieved, track information should appear in the display and it should start playing. If have no experience with the particular unit you're describing. |
| QUESTION NO. P615-7: Pionner auto radio with a bad regulator; TA8214. I need the pinout, Toshiba site skips over this number. |
| Toshiba's site actually has the datasheet (if you read Japanese...). The TA8214K pinout is (1) output#3; (2) selection switch; (3) ground; (4) Vcc (9.3-18V, 13.2V typ.); (5) output#1; (6) output#4; (7) output#2. All outputs are nominally 8.3 Volts. If the selector voltage on pin#2 is low (0-1.2V), output#2 is ON; if medium (2.8V-5.5V), output#3 is ON; and if high (7V-Vcc), output#4 is ON. Output#1 is not selectable. |
| QUESTION NO. P519-9: RCA RP-9555 audio system, the display screen does not light up. The system operates fine but no display @ps501 power con. All voltages are correct. I also have 2.5 volts at all display pins. |
| The display is backlit and the bulb is burned out, you have to remove the LCD panel to get to it. RCA pt# 227520, MCM # 227520. |
| QUESTION NO. P64-2: Pioneer PD-M700 Home CD Player. The Laser lense fell off and was damaged. Pioneer sent a replacement laser pickup which is the same as in the PD-M900. The old laser lights fine, but of course does not work without the lense. The NEW laser will not light at all. We have gotten two new ones, same result. No amount of adjustment will make it fire. There is a service bulletin on this unit but I am told that all it says is to readjust the unit when the new one is installed. We have not been able to get our hands on the bulletin after several aggressive attempts. |
| Check the new laser very close, and look for a solder bridge that protects the laser diode from static during shipping. You must remove this bridge in order for the laser to work. You will then need to adjust the EF-balance and Focus-offset to achieve proper playback. |
| QUESTION NO. P514-7: CD player in a AIWA nsx-4000 system. The CD will spin momentarely (about 10 seconds) then shuts down. It proceeds with disk #2, and the same thing happens. Disk #3 does the same, then it stops. Probably the IC driver is bad, I checked the spin motor and it works OK. |
| Check flat-type-wire for laser optical pick-up. Check EFM & RF signal IC. Check cd micro-control IC. |
| Check the lens of the laser and make sure it is clean. These units are notorious for collecting a fine layer of dust on the surface of the lens. Use a dry cotton tip swab and wipe gently. Canned air can be helpful, but be careful!!! You can permanently damage the pickup with this. When the unit is looking for the disc watch the lens for movement up and down (focus search). If it still goes to the next disc without playing, change the pickup assembly. One more thing to note is that there is a mod for this unit. It has to do with the tray not stopping in the right position (one click to far to the right). You have to add two resistors, and a transistor to the optical sensor that controls the tray position. Check with Aiwa for more details on this if your unit has this problem. |
| QUESTION NO. P514-10: Carvin amplifier. All the power transistors (mosfet) made by Motorola, mark MTW 20n20e. and MTW 14p20 are burned. I do not know the part numbers. Where can I get those original or replacement parts? |
| Several FETs can sub the N-FET, the problem is having a complementary P-FET to match the N-FET. One possibility is to use IRFP240 to sub MTW20N20E, and IRFP9240 to sub MTW14P20; these have specs close to those Motorola FETs. Digikey (800-344-4539) and Newark (800-463-9275) list both IRFP240 and IRFP9240 in their catalogs. |
| QUESTION NO. P413-4: Carlsbro guitar amplifier,"stingray 65watt". Original problem only distortion channel working, channel switch not working. Repaired power supply to get channel switch working. Now there is very low output, I have replaced main output transistors, resistors 'r25 and 26 running very hot. |
| Depending on the output Q's, try to use original part numbers and not NTE subs. Inject a 1Khz signal in the front end-check for signal linearity through the preamp to the output with an osilloscope. Make sure the output jacks' hot signal isnt being shorted to ground. Check for a balanced +/- power supply at the bridge filter caps.(push-pull). Be sure to set bias current as to not overheat the output stage. |
| QUESTION NO. P412-4: Hifi Tuner Sony LBT-D150. Tuner does not receive STEREO, only when you switch to MONO the tuner works good. |
| I do not know this particular model, but I have often encountered this very symptom with other brands; lubricate or replace 'vco stereo multiplex' trimmer (provided there is one and you can locate it). |
| QUESTION NO. P422-1: Technics CD player model # SL-PC14. Intermittently playes at approx. twice the normal speed through track one and maybe part of two, the rest of the disc then playes fine. Have cleaned lens and tried adjusting tracking offset and tracking balance. This player has a voice coil-type laser transport. I even cleaned the ceramic brush block for the pickup transport. Unit will play fine for days in the shop, then it will "skip" a few days after the customer has it. |
| Sounds like the disc motor is bad. This is a common problem for this complaint. If the motor is weak it can not keep the speed locked for the first few tracks. It spins about 500rpm at track1 to 250rpm for the last tracks (outer most). Make sure you measure the distance between the chassis and disc platter before you remove it so you can put the new one back on at the right height. |
| Look at the eye patter, if it undulates back & forth (not up & down), The spindle motor is bad. |
| QUESTION NO. P324-3: Audio.IC TDA7052, made by Philips. I cannot find it in Shanghai. What can replace it so I can buy it in Shanghai, China? |
| TDA7052 is ECG7051. |
| QUESTION NO. P318-3: Older Sansui 990db receiver. I am getting approximately 45vdc on the left output terminals. I have tested all 8 (4per chan.) of output devices for shorts or opens, they test diode DMM ok. The right side works fine and no DC voltage is present. |
| You have a bad transistor on the left side. Your best bet is to replace them all. |
| Check for excess current draw. If not excessive, change differential amp transistors. If excessive, check for open bias transistor and check for open bias control. Sansui's are famous for burning out this control. |
| Check the resistors in the power amp section. Compare with other channel if you have no diagram. These older Sansui's often have resistors which have increased in value due to heat generated by the unit that they will increase or open up. |
| QUESTION NO. P48-7: Where can I find the equivalence of k129a (mosfet) for Pioneer Power Amplifier M90? |
| This is probably NEC's 2SK129A. Techsonic is listing 2SK129 and 2SK129A in its stock, on webpage http//members.tripod.com/~semiconductor/html Audio Lab of Georgia, website http//audiolab.home.mindspring.com/ lists stock of two 2SK129 at $1.80 apiece on its semiconductor inventory page. |
| QUESTION NO. P330-6: Sony Discman Model #D-34. Everything on the player seems to be in good working order, however, the unit skips ocassionally when in play mode, unit is stationary. There does not seem to be any one spot on a disc where this happens. The unit will studder, and then play ok for a few minutes, and then studder again. I have cleaned the optics,and checked the tracing optics, and that seems to be ok. |
| Try replacing the motor for the CD. You may be able to use a cleaning solvent. |
| Check the idler gear between the motor and the sled for broken or damaged teeth. |
| QUESTION NO. P324-8: Teac PD-D850 audio CD multi player (5 disc). Skips regularly (20-70 seconds depending on which track is being played). It backs up and replays a few seconds of the previous material when it skips. Also, when playing the last track of the CD, it sounds like a great echo. It appears that the unit has been dropped a short distance, but I cannot find any PC board damage. |
| Check the traverse gears for a dust or sand particle between the gear teeth. Also check the motor gear under a magnifier. They often split right on the motor shaft causing the teeth to open, thus preventing a proper mesh with the other gears.This is why the time to failure is consistent. |
| QUESTION NO. P222-1: Sony fm-am stereo receiver. Comes on and plays for about 15 minutes. Front goes blank, sometimes keeps operating but dial is not lit. |
| Tear it apart and fix the bad ground conections. You may also have a thermal display I.C. |
| Sony grounds the main & power supply boards thru the chassis (the main board thru the heat sink...brilliant!), After these heat up & cool down enough times all sorts of whacky things happen. Find & tighten all screws on these boards. On the screws with metal tabs on the board, prep & solder the screw to the tab with a high wattage iron. |
| QUESTION NO. P215-9: HH Scott 222C Stereomaster Tube Amplifier. One of the output stage transformers has developed some problem, due to which I'm getting 8 dB less output on one channel. Where can I get the winding details for the output stage transformer? Does the HH Scott company still exist? If so, what is their address? |
| Try the following web site http//www.inquo.net/~lshuster/hhscott/index.htm. |
| H.H. Scott is owned by Emerson. Don't expect them to have much. You might be able to find a salvage Amp for the transformer, otherwise you might be able to locate a suitable Hammond replacement. Antique Electronic Supply does carry them (www.tubesandmore.com). One thing to check too, if the transformer is not heating excessively, check the grid bias on the tubes, and the Plate voltage between channels. These can effect the same symptoms. |
| QUESTION NO. P224-7: JVC BR-8600U would play normally, except when going from reverse search to play. Then it would drag for about 30 seconds and then play at normal speed. Supply tension was exceedingly high which caused the problem. My question is, what is the procedure for tension adjustment on this unit? |
| There is a mechanical spring adjustment on the left side of the cassette loader, but it only adjusts tension over a minimal range. |
| QUESTION NO. P212-4: I need a datasheet Mitsubishi m65841 m65832 m65846. |
| These IC's datasheets have not been posted on the Mitsubishi On-line website. I suggest you get the Mitsubishi contact info for your area of the world, at http//www.mitsubishi-chips.com/contact/service.htm , and contact them for this information directly. If this is a help, M65841 is a Digital Reverb IC, M65832 is a Digital Echo IC, and M65846 is a Surround System Processor IC. |
| QUESTION NO. P112-4: Technics SU-v98 amp. I suspect a faulty power amp IC, SVI3025. What is the pinout for this chip or where I can obtain it? |
| Dalbini carries it. 1-800-325-2264. |
| QUESTION NO. P211-4: Panasonic RX-CT900 portable stereo component system. When playing either cassette there is a ticking type grinding sound. After playing for awhile this sound turns into static and comes through the speakers until you can no longer hear the music. |
| Check the motor static brush or realign the base plate. |
| QUESTION NO. P25-9: Sony Cd player that does not alway recognize a CD once the door has been closed. At times it will not close the door. You push the open/close botton and it closes but then immediately opens again. I have found that if I lift the front of the chassis slightly off of the shelf and allow it to drop it will work properly. |
| Remove the tray, clean everything. Relube the tray and all the slides, this should fix your problem. |
| Check the tray limit switch for proper activation. It may need to be replaced. |
| QUESTION NO. P22-6: Optimus stereo model #13-1253,serial #99225-18498. The problem is a distorted and attenuated left channel at the output. I observed the signal at the input of the power output package and it is still distorted . All Vcc's checked O.K. |
| If you trace backwards from the output you will probably find a bad cap or transistor in the pre amp circuit. |
| QUESTION NO. P22-8: Yamaha RX-350. The left channel goes dead intermittently. |
| Resolder the big coupling caps and/or replace the output ic. Have you double checked the balance and volume controls? |
| QUESTION NO. P128-10: I need a supplier for a board (1-647-927-11,D911U27LGQ7) for a Sony STR D-911 Amp. |
| Sony only is the source for Sony PWBS, unless you can find one out of a unit that has been 'field-scrapped'. |
| QUESTION NO. P124-7: BOSS car amplifier model AVA-650. As far as can tell the main board is good, I can put a signal in directly to each channel and they all seem to work. The input/preamp board had 4 shorted op amps which replaced, every thing else on the board seems ok. There is supposed to be +15 & -15V going to this board but is only +-.61, the 15V is is being dropped across a 390n 1W resistor on the main board. I understand this implies a short on the input board or a diode drop of some kind but I cannot find a problem. |
| Amp is now fixed. I ran a seperate power supply to the problem board and it worked fine, so I hooked back up to the main board and the amp worked fine. |
| QUESTION NO. P121611: Allied Radio (remember them?) receiver, circa 1970. One channel starts making popping/sizzling noises once warm, 10-15 minutes. It is apparently in the phone preamp section, since the radio and auxillary still work fine. |
| Replacements the two transistors on the phone reamp (separate little board) (both ECG and NTE parts are available; got NTE 123 APs, about $1 each.). The transistors have different part #s but both map to the same replacement part (for both ECG and NTE). Also, the wiring configurations are different, this is a definite "gotcha". |
| The transistors are cheap enough, and they can be checked for excessive leakage, but as insurance just replace the electrolytics in the preamps too. They have low voltage ratings, and can fail in the 30 years since 1970. |
| QUESTION NO. P127-9: Aiwa NSX 4000 mini system. When the unit is plugged in, the cd drawer opens and continues to open when closed, even if there are cd's present. Could it be the laser? |
| I cannot recall precisely the NSX-4000. But, if when the drawer is open you see a white ribbon cable on the left side, you will find it to be nearly broken right where it plugs onto the PC board. This is a common problem with the Aiwa NSX series. It causes the drawer to act erratically. To answer your question about the laser, it is not the cause of this problem. |
| QUESTION NO. P1112-4: Pioneer FH-M75 car stereo H/U that the amplifier was toasted in. That is fixed, but now I have a high-pitched whine in the speakers. It does not matter whether it is playing tape, cd or radio. |
| If the sound problem is only with the engine running, check your ground connections. Try running a ground from the mounting bolt on the back of the H/U to a good known ground. |
| QUESTION NO. P1116-2: Pioneer Sx-203 home receiver with what I believe is blown outputs. What happens is that everything turns on and all buttons work. I get no sound from the speakers (no static, or turn on bumps). |
| Pioneer SX-203 blown outputs usually caused by to low of a load, IE, using two pair of 8ohm speakers for a 4ohm load causes too much heat. Replace output transistors and secondary fuse, check the dual emitter resistors at the output befor turning on power. Should be .22 or .33 ohms. If those are open, then also check surrounding components. I find that four out of five times it is only the output transistors that fail. |
| QUESTION NO. P1029-3: (similar to p721-2.) Pioneer made 'suicidial' stereos rx-370, 570, 390, 590... with a "blow line" that deliberately destroys the outputs (and often the speakers) if it senses anything wrong, including pressing too many buttons at once, power dips, loose speaker wires, electrostatic interference, bad cassette motors. I have heard there is an smd transistor which can be shorted emitter to base to disable the blow line, which one? |
| I have fixed several of these monsters and I found something even Pioneer tech support missed. When the unit is in the OFF mode, a design glitch, (a sneak path through an IC) draws one of the supplies which is usually positive when the unit is ON and zero when OFF to a negative value. This causes instant Hari Kari. The cure for these units was to put diodes (1N4007 or whatever) back biased across the supplies in the preamp that are switched on and off along with the ON and OFF modes. These prevent the condition from occurring. |
| QUESTION NO. P1029-6: Have a Fisher RSZ1 Digital Reference Series Receiver. Isolated a defective part marked K398 at the audio section but cannot cross-reference this semiconductor. Need info/data on substitute parts, pin configuration, and any other vital info. |
| If this part looks like a transistor it is probably a 2SK398 which crosses to an ECG2392 |
| QUESTION NO. P104-7: RCA CC-641 Camcorder. It can record, but playing it back no audio was recorded. |
| Will the camcorder record line audio? Will it play audio from an old tape? You probably have a broken wire by the audio head, but may have a bad audiu ic. |
| QUESTION NO. P1025-9: While trying to repair an Onkyo TX9031RDS audio receiver, I found two transistors "RN1241" to be dead. Where can I find data or replacement types for these rare transistors? |
| RN1241 is a Toshiba muting transistor, rated R[on] = 1 ohm @ 5 mA Ib; it has an internal 5.6K (+/-25%) resistor going into the base (ECB pinout). Also, it has a high Vebo 25V, and high gain 200-1200, all making it hard to cross. If your Toshiba supplier cannot provide these, try getting Toshiba's 2SC3327, which has similar specs but no base resistor, and then adding a small 5.6K resistor externally to the base. 2SC3327 is listed by MCM (800-543-4330), B & D Enterprises (800-458-6053), and Union Electronic (800-648-6657), among others. |
| QUESTION NO. P928-1: Sharp DX-650 CD player (D/M June '87) will intermittently stop playing the CD. The CD will continue to spin, but no sound and the time of the song on the display will start flashing. Although the disc is spinning, the time on the display does not increment. Pushing pause and then play resumes the music, but it jumps approx. 1 minute and 10 seconds back and starts from there. Any ideas? |
| I am not model specific but here are some things you might want to check out. Lens clean? Optical pickup moving freely along the sliders? Dried up grease? Broken tooth/dirt on gears? Tracking motor dead spot? See if it continues play if you gently turn it by hand. Connector to optical pickup got a crack in any wire (especially those transparent flat flex cables may be failing depending on bow angle)? Bent shaft of spindle motor (bearing)? Wobble of CD will show scoping Tracking Error and Focus Error. Getting more serious, the nearer to the outer parts of CD just until focus/tracking circuitry gives up. Spindle motor not running stable at lower speeds (brush debris,dead spot)? Measuring voltages at spindle motor during play and breakdown should verify. Injecting contact WL through vent holes of motor could affect it. |
| QUESTION NO. P924-7: Sony stereo receiver str-da80es. When powered up, the unit goes into the protection mode. I have checked the grounds, but cannot seem to find the problem. |
| Protect mode usually means one of two things. Check for DC on the speaker outputs (if yes, then you have shorted outputs). Check all supply voltages. You can also try a master reset, Ground the reset test point. Plug unit in and turn it on, remove ground from the reset test point. |
| Sony grounds the main & power supply boards thru the chassis (the main board thru the heat sink...brilliant!), After these heat up & cool down enough times all sorts of whacky things happen. Find & tighten all screws on these boards. On the screws with metal tabs on the board, prep & solder the screw to the tab with a high wattage iron. |
| QUESTION NO. P917-10: Audio_Equip blown a STK 4171 II and got an STK 4171 X for replacement. But the last one has different number of pins. I could not get a pinout for the X-Version. |
| It is generally a mistake to try to substitute Sanyo STK's with a chip whose number has different Roman numerals; the Sanyo numbering system just does not work that way. For example, your STK4171-II is obsolete for design, and Sanyo recommends as the design replacement IC# STK4172-II, not a different STK4171. But design replacements sometimes are not drop-in replacements, so why don't you just pick up an STK4171-II from a place like B & D Enterprises (800-458-6053) or MCM Electronics (800-543-4330)? Both list the chip in their inventory. |
| QUESTION NO. P94-3 Technics SA-EX800P-K receiver that was overloaded due to speakers being connected incorrectly causing them to be shorted. Since then, the receiver has never functioned and displays the "Overload" screen upon startup without ever turning the amp on. This occurs when all inputs and outputs are disconnected and the amp has had plently of time to cool down. |
| I am not familiar with this model. However, I have fixed hundreds of receivers and amplifiers without schematics by always checking the output transistors for shorts. Find the heat sink and check every transistor for a short. Trace the leads back to the previous stage for shorted drivers. Many less expensive receivers use multipin power chips, about 2"x3". There is no repairing these. Replace the whole module and hope for the best. |
| QUESTION NO. P819-3: JVC Audio/Video Control Reciever, model number Rx-517V. The main power fuse (6.3 amp, 125 volts) keeps blowing out and I am unable to find where the short is in the system. |
| Try putting a lightbulb in series from transformer and the wire to on/off switch. If fuse does not blow, you have a defective transformer. I had the same problem with a similar JVC. |
| QUESTION NO. P812-10: JVC tuner model # FX-330 BK. I have done much searching (ECG, internet) on a voltage regulator located in the power supply, this regulator is an AN7812R, it is a four pin not a three pin regulator. Apparently the extra pin is some kind of a reset. I would like some information on this IC please. 12 volts is coming from the third pin but this pin is attached to a fuse directly to ground, which explains why my meter (while measuring amperage through the fuse socket) shows the current exceeds 0.15A with the line voltage only at 30 VAC. The fourth pin measures over 13 volts. I am very confused on this IC. I believe pin one to be Vinput, pin two GND, pin 3 ?(reset?), pin four perhaps should be 12 volts? From internet searching, a number of people have been asking about this IC, and not really getting the answer. The IC seems to be in a number of JVC tuners with similar model numbers. Perhaps, no one else is using this IC. |
| AN7812R is a Matsushita (Panasonic) 12 Volt, 1 Amp voltage regulator. The pinout is 1) Input; 2) Ground; 3) Output; 4) Reset. The reset pin voltage is 1 - 2 volts (two diode drops) higher than the 12 Volt output voltage when the reset is not under load. Taking the reset pin to a low voltage shuts the regulator down. So it seems your device is functioning as expected. |
| QUESTION NO. P86-9: Working on a Sony model STR-D865. Looking for final pair San Ken MN2488 and MP1620. Is there a generic cross for these or a source other than Sony for replacements? |
| MN2488 and MP1620 are the numbers for the devices Sanken provides to Sony. The industry numbers are 2SD2488 and 2SB1620. If your supplier of Japanese transistors has these latter two, they will substitute, but these will not cross to any generics, their specs are too unique. They are matched NPN and PNP Darlingtons, rated 200 Vceo, 15 Amp, 150 Watt, MT100 case, with minimum gain of 5000. If your supplier does not have them, your most likely bet is still to obtain them through Sony, using the Sony numbers. |
| QUESTION NO. P86-10: Kenwood Stereo Integrated Amplifier KA-127. 120 Volt, 5 amp, 60 hz. Whenever I replace the fuse it blows again. |
| Have repaired KA128 units same fault. Mine where shorted output transistors for one side. |
| QUESTION NO. P724-8: Nordmende Spectra-Stereo 5205 Chassis F 15-02. The problem is that blue has become the dominant color in the picture after replacing the focus unit. I have tried changing the IC01 TDA4556 and the U4606 parts, to no avail. |
| If TDA 4556 is from TESLA, try to it change with another from another company. |
| QUESTION NO. P81-3: Have a JVC XL-V95 CD player in my shop that is real selective in playing cds; doesn't like any CD that does not spin perfectly in balance. Have tried brand new CD's that are such and unit reads back "no CD" upon insertion; tried used CD's that spin uniformly and works great. If I prop the front of the unit up about 10 degrees, the unit plays all of the CDs fine. I can tap on the CD-mech and it does not skip outside of the norm for a single oversample unit. With the out-of round CD's playing fine at 10 degrees front elevation, I can lower the front of the unit slowly and the audio starts getting choppy until it finally cuts out at about 5 degrees elevation. |
| I once had a Philips portable CD player with similar symptom. Turned out the clamp that held the CD down on the spindle table had lost some of its magnetism, therefore not holding the CD solidly. I confirmed this by substituting the clamp by placing small magnets around the hub of the CD and started it playing. |
| Check the spindle motor. A very reliable diagnosis for a faulty spindle motor was to tilt the player a few degrees. These motors frequently develop a wear spot in their cheap bushings, which translates to chattering in the RF pattern. If it will play when tipped a few degrees, it's a good indication that the spindle motor is worn out. |
| QUESTION NO. P731-4: Technics audio amplifier not working, the IC (part SVI3105a) was blownup. I live in Chihuahua, Mexico and the only part similar was an SVI3105c so I put that. It worked fine for a while, then the IC was blownup again. I do not have any schematics or pinout of the IC, so it may be another reason for the IC was destroyed. The new IC's left audio output pin was shortlinked with a power source pin. |
| I would suspect an external problem, not specifically the ic that is blowing the left channel. Improper coupling devices, improper speaker impedence on that channel, or incorrect bias to that section of the ic. |
| QUESTION NO. P622-4: Looking for information on a company, Crown of Japan. I need a power transformer for a model CD-80R compact disk player. |
| Crown (Japan) Ltd., Bharat Bldg. 8F, Minami-Hom-Machi Chuo-Ku, Osaka 1-4-6, Phone: 06-266-1331, Fax: 06-266-1363; # Employees: 2 (!) |
| QUESTION NO. P416-10: Re: GoldStar FH-682R CD Audio Player Stereo Component This unit, when you place a CD into the drawer and push the open/close or play button, accepts the CD by closing the drawer, but the display reads "no" after a few seconds and will not go into play mode. Opening and closing the drawer a few times will remedy the problem and the unit will then play the CD. |
| Try cleaning lens and reflector if applicable first (DO NOT USE SPRAY CLEANER HERE - use 91% isopropyl or denatured alcohol), then spray out bottom of spindle motor if no success. Make sure rails are sufficently greased while your there. Finally try slightly turning (first in one direction then the other) the trimmer on laser unit if there is one but mark it first w/ feltip pen so it can be reset if no good. This will solve most of these problems. |
| QUESTION NO. P41-7: GPX (Grand Prix Electronics) boombox. The model is C996. The problem is the left speaker is not working or very very faint. I have checked out the speaker and it is fine. I am flying blind since there seems to be no schematic. |
| Try cleaning the volume control with a spray type clean tuner cleaner. |
| QUESTION NO. P314-8: Pioneer Deh-225 car audio CD player which the owner hooked up without a ground. The stereo when hooked up properly seems to function, but will not put out sound. |
| Sounds like the installer could have damaged the audio output ICs. If you're getting *no* sound from the speakers (no hiss, power on thump, etc) but still have B+ to the ICs, you've probably got 2 blown ICs. Incorrect installation wiring seemed to be the number one killer of output ICs in car stereo from my experience. Also, very hot IC's are a sign of damage. |
| QUESTION NO. P323-4: Zenith model SC2793P with a Bose sound system. The problem is that it keeps blowing the fuses to the sound board. I need to find a new board. The number is Bose 9-569. |
| From Zenith, if it's still available. Otherwise you may need to have it rebuilt. the 9-XXX-XX is the part number you need to order, when palcing order ask about availability. |
| QUESTION NO. P35-5: Pioneer DEH-720 car cd player which has no outputs. Unit may have been hooked up wrong. |
| Check for flashed pc traces near the DC input. Also the protect transistors may be crisp also. There may be protect fuse-resistors in the DC input circuit. Hopefully the damage is only there, I have seen output devices blown out because of reverse or over-voltage applications. |
| QUESTION NO. P1222-2: Does anyone make and sell a VHS tape with a 1000 hz tone so that can be used to adjust the audio heads of optimum performance in both regular and surround sound? If so, where can they be obtained. |
| You are looking for the Ultimate Test CD, Titled Test CD, by Moss Music Group. Sinus Tones of different freqs, from 20 to 20khz in various db. Including Sweeps, SMPTE Code, Pink Noise in and out of phase. Drum tracks and silence. Either inject it or record just the audio. |
| QUESTION NO. P18-5: RCA model rp-7902a portable compact disc player had 110 volt plugged into it and blew something. |
| I assume the disc player is a portable unit designed to operate on 3 or 6 volts. If so go out and buy a new one. You will not like the cost of repairing unit especially if the board is fried. I've seen many hooked up to car adaptors [ 12 volt to 3.5 or 6 ] that have shorted and applied 12 volts directly to the units. It tends to make a mess of the protecitve devices at the external DC input. I can only guess what kind of thruma 120 VAC would do. |
| QUESTION NO. P1222-7: My problem is identical to question no. 729-4. I am pretty sure my output power (darlington stk-0080) is blown, but I do not have the pinouts to check. Also, if it was an overload, should I bother checking the other components too? |
| STK-0080 crosses to ECG 1322, an AF PO, 80W amp with VCC=+/- 46V typically. Pinout is as follows. 1:input+; 2:VCC-; 3:output; 4 thru 7 have no internal connection; 8:output; 9:VCC+; 10:input-. If you have audio at pins 1&10, and VCC, and nothing at pins 3 or 8, it's bad. Not likely to overload unless VCC is measured significantly higher than 46VDC. |
| QUESTION NO. P1217-5: Technics stereo amp mn su-g90 no power. |
| Check the power transistors that are mounted on the Heatsink next to the output IC. Usually they are cold or cracked solder joints. |
| QUESTION NO. P1125-7: Lloyd's am/fm receiver model H415 - located shorted zener diode D108 in tuner vr circuit. Only marking is C8. Need to know full generic p/n or replacement p/n and/or zener voltage. Physical size would indicate wattage is 0.5 watt. Date of mfg of receiver is 1979. |
| part #he10003= Part # he10003 gen. # 1s188am |
| QUESTION NO. P1026-2: Audio Logic model SC31i (single channel 31 band graphic equalizer) and I cannot locate this company. |
| Audio Logic is made by DOD/Digitech. Their phone number is 1-800-999-9363. |
| QUESTION NO. P1013-8: Technics integrated amplifier model# SU-G75. This is part of an individual component rack system. The fan does not work. The fan itself if good. I checked it with 12 vdc. I can't find anything wrong with the fan circuit. Other than it does have any power going to it. |
| If you are getting voltage to the motor and it is not turning replace the motor. If the motor hesitates at all it is bad. This motor has to turn very easy. I have replaced it with a pioneer spin motor pea1233. It works very well. There are several resistors at the motor connection. |
| QUESTION NO. P:914-3: Kenwood Stereo Integrated amplifier KA-36 I cannot seem to diagnose the problem .The left channel of the amplifier makes a distorsion type of noise and frequently blows out the speakers. I have changed the IC for output which is an STK 4141 II but no luck. One of the condensers on the preamp section was blown and I replaced that as well (50v 47*ƒ). There is nothing else that seems to be wrong. |
| You have a leaky transistor feeding voltage to speaker leads. |
| QUESTION NO. P91-6: Barcelona II model 95844 am/fm, receiver with turn table and 8 track stereo. Everything works except fm receiver. AM, 8 track and turn table work fine. |
| This unit is at least 25 years old. Suspect corroded switch contacts, dried out capacitors, and other normal failures due to age. Also you may come across some actual electronic failures such as a bad osc or mixer transistor. As old as this unit is it may be best to look for age related failures or corrosion even beneath some of the components. |
| Trace with a scope the area around the FM demodulator and the selector switch. There is a probability that the demodulator chip failed, or that the switch fell apart internally in a manner that becomes most pronounced when in the FM position. |
QUESTION NO. P 729-4: Fisher stereo that all the lights are working on all the components but I am not getting any sound out of the speakers, not even a hum. |
| Since you are describing what sounds like an output stage problem, check to see if 2 of the four power transistors (mounted to the heat sink) are open circuited. An NPN and PNP typically exist for both channels (push-pull), and one would have to be blown on each side to get no sound. Alternately, if you have an STKxxxx (or the like) all-in-one stereo amplifier) vice discrete transistors, cross to ECG to get the pinout and check it. Might have blown other components in/around this stage (dual emitter resistors,etc.). |
| You did not state which model, but there some Fishers that incorporated more than one fuse. There is one that is not easy to find, by looking casually at the chassis, but if that fuse blows, that can cause the problem you describe. Alternately, that fuse may have aged and broke internally without being obviously failed- check them all for continuity. |
| QUESTION No. P721-2: Several Pioneer stereos that keep blowing the outputs. I can find nothing else shorted in the output section. The model number is RX-570. I know this has to be a common problem because I work on a lot of the stereos (changing outputs) but these two seem to have a little more wrong. |
| Connect 60 or 75 watt lamp in series with amp to protect from from further distruction. Do not connect speakers or loads! Outputs short when excessive flows due to high bias. Check bias diodes/resistors/transistors. Do not overlook open supply resistors to drivers and pre-drivers. Nothing ahead of pre-drivers is likely to blow output without speaker load connected. Always check for zero volts at output before connecting load. |
| On these suicidal Pioneer stereos, be sure to check for open 220 ohm resistors across each output (these are surface mount type). If one is open the output transistors will blow. |
| QUESTION No. P626-4: Magnavox CD player (CDC550 BK21) in recently. Load the disk in and press play. The unit looks as though it is playing, but the disk doesn't spin at all. After about 10 seconds, I get a very small voltage blurp from either motor(the one that spins the disk or the one that moves the laser) and the thing "shuts off" into the stop mode. It happens all the time regardless of how many disks are loaded onto the carousel changer. I suspect the IC (DIP) labelled TDA 7073 (clearly marked as a phillips part - possibly a motor drive?) which has pins that go to directly to both of these motors. The motors tested fine from alternate DC source. I have no print for this and can't verify the pinout. Short of interchanging this with the other identical IC on the board and checking for symptom change to verify this (assuming the other is fine) I can only order it and cross my fingers. |
| Since your difficulty seems to be in determining if TDA7073, a dual BTL power driver IC, is working properly, you should download the complete TDA7073 datasheet file at: http://www.semiconductors.philips.com/acrobat/2491.pdf. It is an Adobe Acrobat Reader file. |
| Checking the driver ic's is not the problem, replacement of entire laser pickup with motors assembly is the answer. The cost of the assembly is $105 list and the installation a nightmare to put it in [about 4 hours]. The assembly # is 4822 310 11263. There may be a different number for your model. |
| QUESTION No. P519-14: Sansui amplifier AU-G99X is clipping past half power level. It is supposed to deliver 400 watts per channel but cannot give more than 150-200. |
| You may want to double check the output power vs. load specs. An amplifier rated for 400W into 4 ohms will only put out 200W-250W into 8 ohms. Also keep in mind the power meter involved. I am not familiar with this particular amp, but many power meters will indicate power levels for only one impedance. |
| QUESTION No. P32-10: Pioneer VSX-D704s receiver with sizzling, popping noise from left channel. |
| Your problem might be a leaky electrolytic coupling, or bypass cap. Also I have solved a number of problems on Pioneer receivers by resoldering all the components in the problem area. |
| QUESTION No. P217-8: I need a cross-ref for power audio amp IC SVI 3202, 03 or SVI 3206, or description of the pins? These are from Technics Hi-end audio amps. |
| ANSWER 1: Typically those SVIs do not have a generic cross. That is just how Panasonic gets you you will have to order the original from a dealer and pay the $75.00 :-( |
| ANSWER 2: Try Dalbani at 800-325-2264 or EDI at 800-426-6423. |
| QUESTION No. P19-2: Where can one purchase general replacement record changers like the old BSRs? I have many customers who need changers so they can listen to their old records. |
| Record changers available call 1-619-446-2112 |
| QUESTION No. P1230-4: Pioneer ct-f850 cassette deck intermittently stops while playing. |
| If this problem persists when second half of cassete side is running consider changing belt which drives rotative segments of the autostop sensor. |
| QUESTION No. P117-7: AudioSource model AMP ONE. The 24v relay will not pull in because it has 24v on the high side, and 17v on the low side. If I take the low side to ground it will energise and the amp will work until you power off. Both chans ok and 0vdc offset on the spkr lines. The relay driver circuitry seems to be at fault (subbed new relay). The Company AudioSource in Burlingame CA 800-435-7115 will NOT sell schematics or set up anyone as auth svc ctr. All semicond in relay driver tested (and subbed) ok. |
| The problem turned out to be D805, an unmarked zener which, when removed and tested, was zenering at around 7v, a non-standard value. Experimentation determined the best value to be 5.1v 0.5w Ecg5010a |
| QUESTION No. P99-8: Technics SU8055. It has 2- of a STK0050n Amplifiers and the replacements I can find are $50 but I can get a STK0050 for about $10. I cannot find any differences in these chips. Can I use the cheaper ones? |
| Since the STK you are dealing with does not have a roman numeral for a suffix, the general STK you are looking for will probably work OK. It is the ones with the Roman numeral suffixes that you have to watch out for, since there are some differences between them and those without the suffix. |
| QUESTION No. P330-1: Lux MQ68c power amp. It uses 4 proprietary output tubes in a push-pull configuration. These tubes are no longer available and are extremely hard to find NOS. Is there any technical information on this tube? This would allow a possible substitution. The tubes are (4) 50CA10, (2) 6240G. |
| I have a friend who has a large collection of tubes. Email me and I will give you his name.Keith |
| The tubes are expensive and hard to find because they were not widely produced, and while not exactly proprietary for that Lux amp, they were likely only manufactured by one company, and towards the end of mass production of a wide variety of tubes makes them rather scarce. Based on what I can find, and what I do not find- Stick with the old tubes. If you are in the USA, finding those European types in general is automatically more expensive, and much harder to locate. There are ways of determining a suitable replacement in this circumstance, but you need to know the voltage at the plate of the original tube, as well as the voltage of the heater, as well as the |
