Keep losing the plastic tubing?
This extra wire should help.

If you suspect that a monitor is missing a sync signal resulting in it going into power saving try connecting an external 6 volt supply to the crt filament.  Turn on the supply first to heat the filament.  Then turn the monitor on.  You can then see if you have sync, one color missing etc.

A simple com port tester for PC's and other DTE/DCE equipment. Verifies port activity, confirms 1488/1489 line drivers receivers are functioning ok. The reason for the led's on pin 2 and 3 is whether your connected to DTE or DCE equipment. Terminal/PC/MODEM/PLC anything. The jumpering satisfies every handshake known to RS232 communications.
DB25FM connector
Pin number
frame ground PIN 1 ---- n/c or attach to shield at one end only, not needed for short runs
Txd 2-- 1 kohm ----------- + [) red led, anode to 7 ground
Rxd 3-- 1 kohm --- + [) green led, anode to 7 ground
Rts/Cts 4--5 jumper 4 to 5
Dsr/Dcd/Dtr 6--8--20 Jumper 6 to 8 to 20
Ground 7 -- ground -- solder to anode of leds
I built a couple of these with db25fm and db9fm connectors and attached a 2 foot cable to the leds, heat shrunk it all together so I could see what was happening when working on PC's in tight places and other comm devices. This thing has never let me down when testing any COM port. It tells me everything I need to know about the com ports hardware or if its a software problem. If I see activity sending to the port, the port is OK.

If you are having trouble with a Power Supply blowing fuses and are not sure if you got the problem fixed, here is a tip.  Get a lamp socket with 2 extending leads and a light bulb. Solder alligator clips on the leads. Put the clips in place of the fuse. Power up the PS and turn on the bulb. If the bulb goes extremely bright on power up, the short is still present. If it goes dim more than likely the Power Supply will start working properly. It may take a few seconds or flicker if the power supply is a Switching Power Supply. This will save you time and money!

For NAP (Magnavox, Sylvania, Philco, Phillips) console TV sets, a spare 25"or 26" table model set whose chassis has been destroyed by lightning, makes a very good test jig. Just remove the customer's chassis along with the front panel control from any console model from the c5 chassis (15 years old) up to the present models and it will operate in this test jig. The only connection to connect/disconnect are vert yoke, hor yoke, speakers, degauss and dag to crt board and chassis. Two types of vert yoke connectors are used so test jig should have both vert yoke connector types.  Do not try to operate this test jig with 31" or larger as the yoke mismatch as well as pinc components will cause problems.

All CRT restorers, including the most expensive, are based on the same principle appliyng discharges between RGB cathodes and G1 inside the tube to remove from the cathodes microscopical particles deposed on them during the CRT lifetime. Those particles diminish the electron emission, and by removing them the tube may be restored. The homemade device pictured here is good enough to do this work and gives a good service to the TV and monitor repairer in all cases when the tube is not totally unrecoverable (all vacuum electron emitters have a limit). I have tested it with many types of tubes and found it useful except in Samsung and some EMC tubes, in monitors. I guess Samsung tubes are the worst. I have never tested it with Trinitron tubes, but I do not see any reason for not trying it, only that I have not yet met any exhausted tube of these.  The circuit is very simple, and you can make it recovering old materials. The isolation transformer is not essential, it only provides a means for more security. You can use an old tube socket to make the connections described in the picture (you must of course disconnect the tube from the rest of the monitor circuits), then apply the 6 to 9 volts to heat up the filaments for some minutes, then switch off and immediatly push and release rapidly several times the pusher switch that applies the 220 AC discharge through the light bulb, while the filaments are still hot. Do it first to one of the three cathodes, then repeat the whole procedure with the other two. You will see that when you apply the discharge, the bulb lights up and a little spark can be seen inside the tube. As the filaments get cold, the bulb flashes get dimmer as you go pushing the switch. When the light does not light anymore, the discharge cannot be made. Turn on again the filament supply and proceed with another cathode.  Caution! Do not push the discharge switch while the filaments are under voltage, you could damage the cathode. For more security, you can use a double-circuit pusher switch that automatically turns off the filament supply. When the three cathodes are treated this way, test the monitor if it is still dim, repeat the procedure the times necessary, but if you do not see any improvement, let it be, the tube is unrecoverable.  Note the device described, as you see, is intended for use in the countries where a 220 v. AC supply is available commonly. In USA and other countries where they have 120 volts (or other), you have to experiment if the procedure is directly applicable this way. I suppose a 120 volts discharge would do too.

Here is a little item that I use all the time to test power supplies.  Most supplies will not start without a load. I use an automotive brake light bulb. The bulb has two filaments, one I connect to the 5Volt line (Brake filament) and the other to the 12 volt line (running light filament). This bulb is connected to a standard connector. I used an extender cable cut the male end off and soldered the bulb to the Yellow and red wires. Both blacks are attached to the sleeve if the bulb. If the supply is good, both filaments will light up almost the same brilliance. I found it great for debugging supplies. Make sure all the other lines to the computer and hardware are disconnected for this test.

IBM 15 pin 3 row to Apple 15 pin 2 row
IBM 3 row Apple 2 row Signal Name
--------- ----------- ------------
1 2 Red Video
2 5 Green Video
3 9 Blue Video
4 nc
5 nc
6 1 Red Video Return
7 6 Green Video Return
8 13 Blue Video Return
9 nc
10 11 & 14 Grounds
11 nc
12 nc
13 3 & 15 3=Composite Sync, 15=H Sync
14 12 V Sync
15 nc
nc 4 Monitor ID #1
nc 7 Monitor ID #2
nc 10 Monitor ID #3
The three monitor IDs tell the Apple / Mac
video controller what frequencies or scan rates to output - but the PC computer doesn't need them.

Years ago, I built a similar power supply like Ron but needed higher output. It works when using 2N3773 transistors instead of 2N3055. The limit is then 40 Volts and lots of Amps.

For a surprise FREE high current transformer look to your 'junk' microwave ovens. Most shops have some laying around with bad control boards, not repairable (I have nine of them).  Just remove the power transformer, chisel away the 1000vac winding and take some #12 romex wire, single and wrap that around the core where the old hv winding was. Formula= 1 turn per volt. Secure and glue it and you have a transformer capable of MANY amps.

To eliminate a possible bad G2 pot (or to repair it), I have been using following little circuit (5 components).  It uses the pulses from the HOT to create approximately 1000VDC.  Feed this into a pot and then to G2.  You only need three wires from this module:
1 HOT collector
2 GND
3 G2
The circuit (copied from several monitors) from the Hot collector two 1000V fast diodes (BYV96E or equiv.) in serie, to a 10n 2KV cap, then to the top of a 2M HV pot, the bottom of the pot via 1M resistor to ground.  The wiper of the pot goes to the G2 input on the neck pcb.  If you want to connect directly to G2 on the tube (eliminating the resistor and cap already on the neck) you should add on the wiper a 1M resistor to a 10n 2KV cap (as filter).  Of course be VERY carefull when handling, also take care how you mount it it carries over 1KV!!  See figure below.

PC repair has a future!!!!  You can play this little mpg file back on any player.   I liked it and I think a lot of others on the group would too.  Download mms.mpg

When confronted with a Big Screen TV and not having its manual to confirm the locations of and adjustment functions of the pots nor the presence of I.D.'s silk screened on the board . I utilize the following technique

Initially make small reference "tics" on the pot shaft and its case on all the affected pots with a micro Sharpie permanent marker (blue seems to work best). This way you can go back to the starting point(s) if necessary.  Next I utilize a test aid made up from a test lead ~ 2 ft long with a standard size E-Z hook on each end.  Cut the lead in half and solder a momentary contact n.o. spst push button switch to the cut ends. My unit has the mini switch enclosed in the round plastic shell salvaged from a standard size phone plug (guitar...not telex). This permits all the fingers to grip it and the thumb to "blip" the switch rapidly.  Hook up your cross hatch generator to the set and set up a large service viewing mirror back far enough so that you can look back to it and get a full panoramic view of the whole TV screen. Take one of the E-Z hooks and affix it to the center wiper pot of the specific pot you are about to evaluate, place the other hook on either of the pots outer terminals.  A quick "blip" should reveal the color you're working with and it's displacement should clue you in as to its function e.g. hoz or vert bow, skew, trapez, lin etc.  Then you can make a sheet for reference until you locate the needed controls that need alignment. Should you not get a pattern displacement you probably chose the outer pot terminal that already had its wiper element set close to that end , so swap to the other terminal.  Not too many sets utilize variable inductors on the board anymore, but when they do, you can suspicion it's a hoz type of adjustment.  If the coil utilizes a ferrite screw core I use a mini pocket screw driver that has a small magnet on the end of the handle.  Placing this in the inductor shell will skew the inductance greatly and you can surmise its function.  BTW this technique is very useful in rf circuits if you will use an allen wrench that just pass thru your slug, this way you can see the tuning effect on your circuit or identify a coils function without disturbing its initial setting.

If the lamp is broken of course - replace it. Otherwise a bad lamp will still light.  It just won't be a nice white color.  More of a reddish orange, only lit on the ends or flickering just like any other fluorescent lamp.  You can, of course, try to measure the output of the inverter but with the loading effect of the meter/scope and the fact that it's a high freq AC output I wouldn't know what to look for.  Lamps are only about $10 so that's where I start. Even if it doesn't solve the problem you can still charge the customer, you just tell them there was no sense putting a new inverter onto an old lamp so you replaced it while you were "in there".  I personally wouldn't want to warrantee a laptop with a new inverter and a used lamp.  If it comes back next month with the old lamp burnt out you'll be replacing it for free under warrantee.  The customer doesn't know invertors from lamps so they'll assume because the display went black last time and the symptom is the same that you'll cover it.  Lamps and invertors can both be had from JKL through Digikey.  The biggest problem with invertors is their physical size and mounting holes.  I read the warrantee card on a KDS LCD screen a few months ago, in fine print down at the bottom it said that the lamps AREN'T covered by the warrantee.  This means that if the lamps go out while it's under warrantee the unit goes to an authorized service center and they change them but they get to bill the customer for the work.  This may increase the revenue of those that are authorized because they will now get paid for a lot more units by the customer instead of KDS but it's also going to make for a LOT of very unhappy customers.  I currently get $135 Cdn to change the two lamps in an LCD. We always change both, no cheapskate onsies thank you very much.  Lamps are about $10US - $15Cdn ea so labor shows $100 which is comparable to what I used to get for a monitor repair.  My advice is to go to the places that sell these and get in touch with the manager, show/explain to the manager that the lamps aren't covered and that if his customers come in with this symptom they will be better served by sending them to your shop for faster service.  A lot of the big box outlet stores take the returns and send them off to a depot.  This could leave the customer without his unit for up to a week and they'll still get a bill.  In the next 5 years a lot of these will be failing, the lamps only last a couple of years if left on all the time.  Although I strongly disagree with the idea that LCDs will replace the monitor any time soon (read in the next 10-15 years) I don't let opportunities slip by either.

Using a camcorder, look in the viewfinder while the camera is looking at the output of the remote. The camera is very sensitive to infrared and works as a great converter so you can see the pulses of data sent by the remote.

Use an ordinary AM radio for testing remote control by simply pushing some remote button near the radio and moving the dial near the 500 Khz.  If the remote is working you can hear the tone burst from the remote oscillator.

Plated-thru holes with small clearances are the worst. In these cases I sometimes use a dremel tool with a cutoff wheel to cut the leads free of the chip. The leads can then be individually heated & removed by using just an iron. The holes can be be sucked clean after all the leads have been removed. This is probably a slower process, but it guarantees that no foils will be damaged in the procedure. This works well for SMD devices too.

I have a '90 Legend LS with the Bose individually amplified speakers.  Three of the four speaker amp combinations were very low volume with some motorboating (low freq. oscillation) in the rear speakers.  I replaced all the electrolytic capacitors (the can-shaped ones) with new ones, as I have heard they leak out their electrolytic fluid over time, causing the gain to go way down, as well as the motorboating and, in some cases, a whining sound.  I used a signal generator to inject a 1000hz signal into the input, as well as my bench power supply to give it 12vdc. After each cap was changed, I flicked on the power and verified that the tone was coming out of the speaker. I observed that after replacing a few of the smaller caps that the gain greatly increased, and after replacing the larger caps that the motorboating vanished. I also replaced the four output transistors on one amp, in the case of this amplifier, they were n-channel mosfets. The device number on the existing transistors is apparently a proprietary Bose number, so I substituted an IRFIZ24N, which seems to work fine. If you're not proficient in soldering, get a friend who is, as it's easy to ruin your amplifier.

Nicachon Capacitors leaking in 1991 and 1992 TV's Mitsubishi, Zenith, VCR Supplies.  One Mitsubishi had 2200mf caps in supply and ones in computer output-to-video chip for tint color 47mf etc. that caused video noise in picture on a 35 in.  Look for black solder on bottom of board, black specked traces on bottom and round brown cicles around caps.  Caps are blue and black in color.  Just look for Nicachon.

Having a problem finding a suitable tyre for a cassette player?  Most times I can get the correct width but not the thickness.  You can build up the size of the wheel by applying small strips of adhesive label carefully cut out to fit inside the rim of the plastic wheel then put in place the replacement tyre.   Have restored many cassette players that would otherwise been scrapped.

Take SuperGlue / CrazyGlue and apply to surface that needs rebuilding or gluing together.  As soon as possible take a pinch of baking soda and sprinkle on the Crazyglue. This causes the Superglue to set instantly, approx. half a second, and also builds up the surface. This leaves the Superglue and baking soda as hard as granite -no exaggeration.  I have not yet found anything that can compare to the strength and holding power of this stuff.  Very useful around plastic.

I found that the best way to test infrared remote controls from all types of equipment is to place them in front of any handheld video camera (VHS or VHS-C or 8mm) and push any button on the remote.  You will see a series of rapid pulses in the viewfinder or LCD panel indicating that the remote control is working.  Also on remote controls that have more than one infrared LED you can easily see if an LED is not working.  This is also an easy way to test for buttons that are stuck because of dirt on the remote control.   This method could also be extended to test any device that uses an infrared LED such as infrared barriers.  That is because the CCD device used in camcorders is sensitive to infrared.  And even better, if you have a digital camera with an LCD screen (I am referring to the ones that are used with PC or Mac computers and are able to store images on floppy disk or PCMCIA card) they can be used as well.  As they become less expensive and smaller, the advantage is obvious - portability to a customer's site. Try it, have fun and be productive!

The one thing I have found that causes the most problems in VCR's is the mode switch.  They come in all shapes and sizes and are usually very cheap, low-quality items.  Do yourself a favor and at least clean and lube the mode switch in every unit that shows any kind of mechanical wierdness.  It just may save you a whole lot of time and effort.

If the CRT is shorted Focus to G2, one technique that we use is to disconnect the G2 wire from the CRT PCB.  Then, power up the set, and when the focus voltage backfeeds into the G2 and builds up a potential, it will arc thru the G2 circuit protector to ground and Voila,  short is gone!  If the CRT is shorted HV to Focus, we remove the CRT PCB, and hold a grounded screwdriver about 1/2" away from the focus pin. Again, after power up, the resulting arc usually clears the short.

Capacitor Leakage - submitted by Peter Gottlieb with an addendum by Jeff Roberts

Editors Note: A series of messages on this topic were posted to AnaTek's ELREPAIR email discussion group. The postings of Mr. Gottlieb and Mr. Roberts were so helpful and authoritative that got their permission to post them here for everyone. Thank you Peter and Jeff. 

I have seen quite a few mentions of capacitor leakage, and some references to the "acid" that leaks out. I would like to correct this misconception and explain what I have found out about the construction of electrolytics and the dangers of leakage.

As you may remember from physics, to get high capacitance you need either a large surface area or very close spacing of the electrodes. Since large surface areas, even in a jelly-roll type construction like in an electrolytic cap, are impractical, the solution is to get very close spacing between the plates. If you open up an electrolytic you will find a plain aluminum plate, an "insulator", and an aluminum plate with some sort of coating. This coating is actually the insulator and is very thin. What seems like the insulator is actually a porous holder for an electrolyte solution.

The electrolyte used in most electrolytic capacitors is a salt solution in a solvent. This solvent is not water (it would freeze too easily), it is some hydrocarbon (frequently DMF, dimethylformamide). The salts used are proprietary to each capacitor manufacturer but are not table salt!! The DMF is itself not corrosive and will evaporate once the capacitor seals are breached or the DMF escapes the can. It is the salts that are so corrosive to the circuit traces, especially in damp or humid environments.

Now for the problems. A dry salt is not corrosive or conductive, but add moisture and major problems start. Any high impedance circuits can be shorted out or pulled to the wrong state. Power circuits will corrode, short out, and can even catch fire (it was a fire investigation where I learned of this "interesting" possibility). If you find a capacitor that has leaked, you MUST thoroughly clean the residue from the board or you may end up with a call-back. This has happened when a repair is made when it is dry out and then when the humidity increases the camcorder or whatever no longer works properly.

I saw a comment that corrosion can occur some distance from the leakage. This is because the solvent can carry the salts further than you may think. You really need to do a lot of cleaning. A few of the salts are UV visible so if you have a UV lamp handy give it a shot, you might get lucky. If a lot of caps have leaked the unit may be Beyond Economical Repair unless you can do a bulk cleaning of the board.

Jeff Roberts added:

Just to add to your explanation a good way to bulk clean. We have a particular power supply where the electrolyte leaks out and makes a real mess, not only does it corrode the traces but it can be conductive which makes for "extra" traces and shorts and a whole mess of problems.

We remove all of the caps and use a Q-tip and alcohol to start the clean up process, we then repair/replace any damaged traces and then we put them into the dishwasher and let it wash and rinse them. We don't use the dry cycle but stop it and just let them dry up overnight or with a hair dryer, then replace the caps and it's done. This works great!!!

The boards clean up like new and all of the electrolyte is cleaned off so there is no future corrosion or problems. Dishwashing soap is VERY powerful and combined with the high pressure water jets the job it does is great, after all if it'll clean the lasagna pan - a little chemical spill is nothing. Best of all it's cheap and much faster than trying to hand clean a board.

NOTE: We have an old dishwasher that belongs to the shop. I would not advise that you wash any dishes along with any circuit boards since you may end up with electrolyte on your dishes - YECH!

The following question was posted by a subscriber:

If the solvent or DMF has not evaporated, is the electrolyte conductive? I would assume so, as I thought the electrolyte serves to bring the capacitance up by allowing charges to migrate very close to the next layer. Perhaps you could clarify your description of the construction, as I am confused as to what you are calling the "insulator" and the "coating", and why the electrolyte is used.

Peter Gottlieb's answer:

To answer your question, yes, if the solvent has not evaporated the electrolyte is conductive. The "solvent" is no more complicated than when table salt is dissolved in water. When wet, it is conductive and corrosive (due in part to plating/electrolysis) but when completely dry the salt becomes an insulator. Of course, salts tend to absorb moisture from the humidity in the atmosphere so once you get a salt solution on something there will always be a leakage until it is cleaned. A good example of how salts absorb moisture is the salt calcium chloride, which is used as sidewalk deicer.

If you leave a cup of these granules out in a humid area they will absorb moisture until they all melt together into a wet mass. Dessicant packs are made of this same salt, and you can make dessicant packs by sewing a bunch of this salt into a fabric bag.

As for the construction of an electrolytic cap, one aluminum electrode is coated with a thin oxide, and this nonconducting oxide is the insulator in the capacitor. However, this oxide has a rough surface. To get the other plate of the cap mechanically close to this rough surface requires a trick - make the other plate a liquid! Thus, the electrolyte is really the other plate and the electrolyte is in contact with the bare aluminum plate connected to the other terminal. There is a porous (usually paper) separator between the two plates and this serves two purposes: hold the liquid electrolyte solution, and keep the two metal plates from touching each other.

You may ask, why can't the two plates touch each other if one is coated with insulating oxide? The answer is that they can touch, but vibration or shock (mechanical) or a sharp bit of dirt could break the oxide coating and then the cap would short out.

So, in short, the oxide coated aluminum plate is one electrode and the insulator, and the electrolyte and bare aluminum plate is the other electrode.

 Regarding cleaning, I had read that Tektronix puts their scopes in a spray booth and uses hot water and mild detergent to clean them when they are sent in for major service. This is followed by a day in a 160 degree F oven. I remember that their comment was that the water was least damaging of all cleaning methods.

I used to wash off PDP-11 computer boards in the sink when they became dust encrusted and this really freaked everyone out. One of my bosses called DEC to ask if this was OK and was told that this was actually the preferred cleaning method. They still thought I was weird, but that is another story...

Nowadays, with the concern for the ozone layer, all PC board manufacturing uses water-based fluxes and hot water cleaning. However, there are some components that cannot withstand this and they must be installed after the "wash." Some parts have little plastic seals that are removed after the wash, like DIP switches and piezo buzzers. Before you just wash any old board you have to be able to identify whether any components will be damaged and remove them first. You can sometimes tell by those components not having clean connections, an indication they were installed manually after the PC board wash cycle. Relays will have an epoxy seal if they can handle washing. Do not wash a relay that is not sealed, you will ruin it.

Take the good diode and solder a 1K resistor to one end, then apply about 24V across it with the positive of the voltage source to the banded end of the diode.   Now measure the voltage across the diode only with your meter.  That will tell you its zener voltage for replacement.  The 1K resistor is necessary to drop the excess voltage i.e. if you apply 24V and it is a 10V zener then the resistor will drop the other14V and will limit the current to 14/1000=14Ma. Power will be140mW across the diode-more than safe for a 1/4W zener or above.

I have serviced several Philips model 09PS10C portable color TV sets, and have discovered what I believe to be a manufacturing or design flaw that can lead to a premature demise of the set. There appeared to be a common thread to the failures in all three sets. On closer examination, the fuse on the line voltage converter module was blown as if an overload had occured. The main DC fuse on the TV chassis was not blown on two of the sets, but evidence of overvoltage on several electrolytic cans was visible (tops domed-out to almost bursting) in all. The line-converter main switch transistor was blown in all cases.   Separating the line-converter module from the set and repairing it, I noticed that its DC output at no load was up around 35V, and well over 25V under load, which was peculiar since it was feeding a common DC point that can be externally powered from 12V. There is a 25V electrolytic on this line, so I would guess the DC level should be no more than 16 to 18V if properly designed. Since I have no schematic of the unit, I relied on common sense for this estimation and assumed that more than just the switch transistor was faulty with the converter. The design is a typical flyback type with a crude regulation loop formed from a negative voltage that sets the switch bias and controls its duty cycle. The negative voltage is produced by a separate winding on the flyback transformer, and is rectified, filtered, zener clamped, and tied to the switch base through a bias network. The negative voltage filter cap (C609) is a rather small size 47uF 16V electrolytic, which I would guess has a relatively high ESR at the frequency of the switcher (40-50kHz). My theory is that it heats up from the fast, tall spikes coming off the regulation winding and dries out, allowing fairly large current spikes to be driven into the zener. The zener fails, or becomes leaky or resistive. When this happens, the DC bias drifts up towards ground, which increases the duty cycle and hence the DC output voltage of the converter. With the zener open (as found in one of the sets), the DC output hit over 35V with no load. In this particular set, about 6 or 7 transistors and fusible resistors had to be replaced to get it working again, since the 35V killed the secondary regulator and was briefly presented to the 10V DC bus on the TV chassis. The fact that the converter is always powered when plugged in allowed the high voltage to develop while the set is turned off.  The simple fix here is to replace the cheap, obviously under-speed capacitor on the converter module with a better one, such as a 47uF 63V with a 105C temperature rating. A quick external diagnostic is possible. The DC jack at the back og the set presents the converter output on the spring contact when no plug is present. By CAREFULLY poking a sharp, slender probe tip to the spring without disengaging it from the bypass contact, the DC output of the converter can be measured without opening the set up. If you see 25V or more, unplug the set, and replace C609 and the zener (5.6V) before powering it up again. Note that because I did this without a schematic, the zener voltage was a trial and error affair. The TV-on DC voltage appears to be 15V with 115VAC mains, and around 18V when off.

Years ago I was on the road repairing color tv's and also training would-be television technicians.  Firstly I would not be carrying CRT testers, Oscilliscopes etc up 20 flights of stairs to service somebodys TV.  I had to make some sort of diagnosis without all this.  I taught my trainees that in most situations you do not need all this equipment apart from looking as if you known what your doing and impressing people. We were at the job to fix it, not to look impressive.  In the case of a suspect CRT, if the filaments voltage is ok and glowing, the EHT(HV) is ok and there is a couple of hundred volts on grid two.  Then by shorting out momentarily the cathodes of the three guns one by one with your dummy load mains lamp (all real techs do have one do not they) to deck (earth/ground).  The result you should get is a very bright red, green or blue raster with retrace lines momentarily.  If you do the picture tube is 99 percent ok.  And you should start looking at drive or major grid one problems.   I usually short the collectors momentarily of the RGB output transistors via the light globe if the unit uses transistors so as not to accidentally short the wrong pins of the CRT.  Try this tip on a known good monitor (or tv) to see the effect and thus have that extra experience to allow you to judge the condition of a CRT.  I hope this makes sense to those of you out there that do need to learn.

Something that may be a little more convenient for some; circuit breakers.  I have a set I keep around for consistently fuse blowing problems from about 1 amp to about 7 amps. Just reset every time they trip until you correct the problem. Connect to existing fuse base with alligator clips.

Take a can of shellac or varathane.  Solder 3-4" wires onto the four corner pins of the transformer so you can hold it by the wires.  Holding onto the wires so that the transformer is inverted and level lower it into a can of shellac or varathane so that it is submerged up to the pins but do not get the pins wet. Remove and hang to dry for a day or so. This has quieted quite a few noisy coils and transformers.

Remove the CRT card from ther CRT. Ground the G2 pin with jumper clips.  Connect the focus pin to a screwdriver shaft. Apply power momentarily to get the HV up. Unplug the power and quickly touch the screwdriver to the CRT anode. Discharging the HV from Focus to G2 often removes internal shorts.

I can check 10 resistors on a monitor pcb in just under 2 minutes whereas pulling a leg out method and getting it back in the hole, remembering to soldering them all as I have missed a few in the past takes me almost a 1/2 hr.  Now what I do is cut one of the leads/legs of the resistor about 1/2 way between the resistor body and the point it enters through the PCB.  Measure it, join it back up and drop a bead of solder at the cut.   Its very fast and I can now tell which resistors I have tested.  Never had a problem with the 3 watt and larger resistors separating from excess heat at the solder joint either. I figured if the solder does melt at this joint, it would probably be for the better than otherwise burning up something or starting a fire.

This is a sure fired way of finding your fault:  Set your watt meter to 1.5 amps and 0 volts. Turn up the AC until you start drawing 1 amp for 25 seconds. Turn off AC feel around for the hottest component and there you have it. These are the easiest to find.  Do not let the AC go higher than 16v.

When looking for that elusive bad connection on a circuit board a plain old toothbrush is your best friend.  Simply run the toothbrush over the board till your push the bad connection into working. This works great on cold solder joints.

When you have a Monitor power supply blown up that uses the old favorite uc3842 chopper driver ic. ie, blown mains fuse, shorted fet, etc., a quick way to determine if the uc3842 ic has survived without taking it out of circuit is to measure pins 5,6 and 7 as if pin 5 was the base of a npn transistor, using an analogue meter on rx1.  If it reads forward with negative lead on pin 5 and o/c with positive on pin 5, chances are 99% ic ok.   Have found this a useful check and saved replacing uc3842 for no reason many times.   (Murphy does play a part 1% of the time.)

Substituting a HOT is a tricky business as explained in countless repair articles, so use my advice at your own risk.  I provide this information only as an example of the reasoning process I used to successfully replace the HOT in a monitor that I own.  In servicing this 19inch Monitor, I discovered the HOT and its current limiter FET both dead.  The FET was cheap and readily available from a large catalog order distributor, but the HOT turned out to be an expensive hard-to-get 1500V 12Amp non-IDD BJT with no (free) detailed data.  Having no schematic, I checked all semis and passives around the flyback, HOT, and E-W  circuits, and found an open power resistor in the HOT base drive circuit which I speculated to be the primary cause of the destruction.   However, I decided that a low-cost, easily obtained substitute of the HOT would have to be used in case I was wrong.  In order to determine the HOT parameters I couldn't find, I first determined that the Hdeflection and HV flyback were not separate circuits.  With a specified H-scan rate up to 96KHz,  the HOT could be subjected to a 10usec cycle, and thus would have to be a newer generation (at the date of the monitor's manufacture) BJT with high peak Ic and the faster Tstg / Toff times of around 2usec and 0.1usec, respectively.  Filtering for the parameters I learned of the original, I found a sub based on this reasoning in the readily available BU2527AF, a relatively inexpensive high performance non-IDD BJT.  As a bonus, the monitor maker had provided a second mounting hole to accommodate the slightly different SOT-199 package of the sub (manufacturing option, no doubt).  Replacing the HOT, the FET, and the resistor yielded a working monitor with a steady, bright display that doesn't overheat or shut down.  I haven't touched the base drive circuit at all, so I'm not sure if this was just dumb luck, or the monitor design has good margins, or perhaps the substitute happens to be a dead-ringer for the original.  I haven't scoped around the flyback, but the excellent picture and monitor behavior would suggest that I don't waste my time.  The only mod I made was to upgrade the rating of the failed resistor by a factor of 2.

This tips works fine only if the pinch roller is glossy and/or with pits.  If there are radial cracks near the borders, it will not work properly.  Press the pinch roller between two fingers and look if radial cracks become visible.  To give a second life to the pinch roller of a VCR or a tape deck, use a very fine grain sandpaper of at least 1000, 1500 is better. Take the pinch roller with your fingers and roll it on the sand paper on a hard leveled flat surface. The movement of rotation on the sandpaper needs to be in the opposite direction of the movement of translation. If it is not done this way, the pinch roller will only roll without any effect. If the pinch roller is locked in the same position, it will be oversanded in one area and not sanded in other areas.

An alternative way to use the sandpaper is to cut a small piece of it, hold it in one of your hand and pass it over the pinch roller that is held with 2 fingers of the other hand.  In all cases, don't overdue it, stop when the glossy appearance and/or the pits disappeared.

Another way is to fix the pinch roller to a lathe and pass the sandpaper on it while it is rotating.

1) On some models, the carbon rubber is thick enough, only the surface has lost his conductive properties. Use a very fine sandpaper, like 1000 grain, and gently remove the old surface of the carbon rubber to expose the new surface.  This tip doesn't work if only the rubber surface coated with carbon. This tip work fine if all the rubber has the carbon mixture incorporated in it.

2) Salvage an old or cheap calculator keyboard. Cut the carbon rubber contact's tip from one key and place it on the other key, from which the defective rubber contact has been removed. I found that one of the following glue methods works fine, depending on the rubber material pure silicone sealant (for bathroom) or 5 min. Epoxy glue, 24h epoxy doesn't work. The glue needs to stay flexible when hardened.. To select the appropriate carbon rubber contact, it is best to make measurements directly on the exposed surface, with the two tips an ohmmeter to find a similar resistive material. This is because some circuits use a current or voltage comparator circuit. So if the resistance is too low or too high, the circuit could make false triggering of the corresponding key.

A way to build a custom belt for VCR, is to use an old bicycle tire tube.  It can be cut in circular strips with the desired width.  It can also be cut in angle, to obtain a different diameter length.  This tip only work for belts that are not timing sensitive, like the loading tape belt, because a lot of circumference imperfections are present.

This is useful when you have a CRT short from any cathode to heater.  The aim is to apply an ungrounded voltage to heater pins.  First cut all traces that goes to the heater pins on CRT board.  Then take a wire, make one (or more) loop around FBT core and apply the 2 ends of the wire at the enter of the schema.  This signal is something like AC signal going from –10V to +15V at the Horizontal frequency rate.  So the diodes avoid any negative voltage, the caps are doing a nice flat 15VDC and the regulator make the 6.3V required for the heater.  The LM317 has to be mounted on heatsink.  I have added one more diode in input just to drop 0.7V.The less the input is the less the reg heats. Connect to 2 output pins directly to the heater pins on CRT board.  First thing to do is to check with your scope the output voltage of the wire looped on FBT, may be you’ll have to do some additional turns to increase voltage.  You can replace the 1K resistor by a 5K pot to adjust the output voltage.  Heater usually draws something like 1A.  This has saved 3 Trinitron CRT for me.  

This works for multisync monitors. 99% of the monitors I have seen are using a DC voltage for filament.  Thanks for any feedback if it doesn’t work for you.

Burn hard black plastic material to stop the leaking.  You can use silicone, it works too.

We have a solder pot, it is a ring of stainless steel about 8 inches across welded on top of a base plate of regular iron.  Try to picture an 8-inch circle of iron (solid across the diameter) then picture a large ring, also 8 inches across but only 1 inch wide that gets placed on top of the solid piece.  Weld the ring to the plate around the INSIDE of the ring so it becomes a reservoir.  Buy bar solder from the hardware store, usually used for sheet metal work, about $8.00 Cdn per bar.  Place the plate on the burner of a stove, it is about the same size as one of the small burners, and turn the burner to medium, add a couple of bars and in no time at all you have a pot of molten solder, place any old circuit board across the top of this rig and it unsolders all of the components that touch the reservoir at the same time, you merely place it down and start pulling parts off with your pliers, you can depopulate a monitor circuit board of all it's valuable parts in about 2-5 minutes once you get the hang of it.  You can breakdown/depopulate 20 monitor boards and do the cleanup and preliminary sorting in a 6-hour shift.  You won't need to buy parts unless it is something special, like a Sony IC or a strange video driver.  My transistor bins are all full as are my capacitor bins, thyristor bins, bridge bins, coil bins, and IC bins.  I have cross reference books so I can always find a good sub from my own stock.

CAUTION:  Wear heavy clothes, long sleeve shirts, goggles and gloves.  If a capacitor falls off a board and lands in the pot and goes unnoticed then a minute or so later it will explode!!  And you get solder everywhere (yourself, ceiling, walls floor etc.).  So you have to be careful.  It also smells bad, because the materiel that the circuit boards are made of does not like to heat up like that, fiberglass boards are OK but pheolic smokes and stinks bad.  We have a large fan in the window to exhaust the smoke and we open other windows and doors to keep the air fresh.

Replace or toss the machine!  Get a jar with a screw-on lid (have had success with a sealable plastic parts bag too).  Drop in the mode switch, spray in a cleaner spray that has oil in it (Nu-Trol for one) to just cover the switch and let soak for 24 hours.  Remove from jar and spin with a screwdriver, repeat if necessary, dry and wipe off.  To be creative, put a piece of thin foam in the bottom of the jar, drop in the mode switch so that a slot or gear is up, drill a hole in the lid for a screwdriver, cover with fluid.   Drill a hole in the lid for a screwdriver, cover with fluid, soak and then insert screwdriver, push down and spin the shaft under the cleaner fluid.  To preserve the fluid for reuse, use a second lid or seal original with tape or a screw with a rubber washer.  Can be adapted for other carbon or brass wiper devices.

When replacing the EEPROM in an RCA set, sometimes the horizontal is so far off frequency, it is hard to see the parameter number when going into the service mode.  To make the numbers visible, switch to the alt input, or disconnect the antenna.  With no video input, the number will be clear and stable.

Use "Scotch Brite" scouring pads. They are usually available at Home Depot, in the paint department. The pads are plastic, therefore won't damage the cap shaft and have the scouring power of "00" steel wool.

When you replace a broken back with a new one from the manufacturer you find that there are no labels such as Model number or serial number.  If you freeze the label you will break the glue bond and can take the label off the old back with no trouble and if you are lucky you can stick the label on to the new back with out applying new glue.

Use CRC oil to remove old labels.  Let it soak in for 15 to 30 minutes and most labels will then easy peal off.

Wrap the braid around the FBT pin and press the solder iron on top to soak up the solder.  Works better sometimes than plain (or heated) solder suckers.

Your Fibre glass pencil used for taking paint off PCB tracks can also be used to clean Iron oxide off VCR capstan spindle, but you may prefer to use brass refill.  Saves a lot of time compared to using IPA.

A great repair for capstan gone shiny or slippery is have the roller on the capstan arm to hold it even with a small grinder.  Turn on the grinder, switch it off right away and let the roller spin at about a 10 degree angel to freshen up the rubber just like new.  Quick repair and it lasts if the rubber is not dried up too much.

I have used this on many occasions to repair plastic parts that would not glue together for strength. This repair makes the part stronger than the original. The repair material can be a paper clip because it is so easily workable, or a lead cut off a small value capacitor or off a 1/4 watt resistor.

What is DAS and why do I need it? - submitted by Kurt Hanson.  Kurt is a member of our email discussion groups.  All subscribers have access to his, as well as over one hundred other technician's comments and expertise.

As time goes by, more and more monitors are being built with microprocessors or microcontrollers incorporated in the circuitry. The use of these controllers allows for more user/servicer adjustment options at a lower manufacturing cost. This increases the profit margins of the manufacturers. These processors were once only found in the expensive Sun, Sony, Taxan monitors, used in desk top publishing/CAD businesses. Now they are in virtually every monitor made today.

The modern (post 1994) CRT's are "weaker" and do not last more than a few years, without losing picture quality. (Grey scale or white balance, focus and brightness.) These CRT changes make it necessary to readjust them by using some sort of Digital Alignment System or DAS. Sony DAS is not new. It was first used or designed in the middle to late 80's. It is a way to change or rewrite data bits into registers that are processed by the controllers, using simple, basic serial communication.

Sony's DAS system is protected from piracy by using a "key" installed on LPT1, or printer port. This "key" must be installed for the DAS program to initialize. I have been using the Sony system since 1991. My DAS system was put together for almost $10,000. I am Radius, HP, Compaq, Sony, Apple and Digital certified for component level repair... I have worked for a big corporation for a long time now.  I certainly couldn't afford that amount on my own.

I understand that you can get the basic DAS system (software and hardware) for under $1000 now. My system is NOT basic! I can do DAS adjustments on most all monitors now. Major brands at least. Some are certainly not worth the time though.

A common mistake in tape deck repair (both audio and video) is to use the fluid supplied with cleaning tapes or cleaning kits (OR alcohol). Most cleaning fluids contain mostly alcohol. Alcohol is BAD for rubber parts.  It actually makes them get harder. Not only should we be cleaning off tape residue, but we should also be softening the surface to better grip the associated idlers, capstans and especially the pinch rollers. Houshold Ammonia works infinitely better for all rubber parts. You will find it nicely softens as it cleans. You can even soak parts in it. It will not degrade the rubber as many solvent type cleaners can. DO NOT clean the heads or metal parts with it as it IS corrosive.  If you religiously clean the pinch rollers with Ammonia you will see a marked improvement in the performance of all tape drives and many less machines that eat tapes.

The idea is to sort the screws and miscellaneous metal hardware in such a manner that when it comes time to reassemble there is no guess work. Cut a square of cardboard about 6" by 6" or 8" by 8" or 6" by 8" or whatever size is appropriate for the type of electronics you disassemble. Glue six or eight magnets about one or two inches apart to the cardboard. Glue in rows, in columns, or any order. It doesn't matter if you use square, rectangular, or round magnets. Radio Shack carries a good selection. I prefer to use the round ones with hallow centers. Next, take the same number of "post-it" notes and cut them into strips using the sticky portion of the note.  Begin to disassemble the device. Place the first set of screws on the first magnet and record their location on the "post-it" note label. Using the adhesive label stick the label to the cardboard or secure the label with a tack to the cardboard above the magnet holding the screws. Continue to disassemble placing each subassembly's screws on a separate magnet with the attached label. If you run into a nylon screw/washer place it into the center of one of the round hallow magnets (using the magnet as a cup). Use smaller magnets for smaller screws and metal hardware; use larger magnets for larger screws and larger metal hardware such as pinch roller arms, etc. The screws and metal pieces are neatly sorted by assembly and secured to the magnets. You can gently pick up the board and move it to a safer location knowing that after one hour or two days or two weeks the screws will go back to where they came from. If you plan to move the board place a "post-it" note identifying which unit they came from. And remember, some of the devices or subassemblies you work on are sensitive to external magnetic fields so use common sense in keeping the 'mag-board' a safe distance from them.

If you can visualize a Mr Coffee filter, cut down the side ribs to the round center,about every third rib.  Will end up looking like flower petels,now,cut out the circle at bottom, detatching the petals.  Holding a dozen at once, you end up with many little square wipes and some larger round ones.  They are food quality, so no dyes or contaminates, lint free, slightly abrasive,and very cheap!

If you have a scope and a signal generator you can easily build something like an ESR meter.  All you need is two resistors, three BNC jacks and cable.  I feed a voltage divider (2.7 KOhm in series with 5.6 Ohm to GND) with a 100kHz sinus signal from a signal generator.  The scope and the capacitor probe are connected in parallel to the 5.6 Ohm.  During measurement the cap will be in parallel with the 5.6 Ohm resistor and decrease the output amplitude of the voltage divider.  Adjust the the signal generator to get maximum amplitude in the 5mV/div range of the scope.  I use three resistors for calibration 1, 3.3 and 10 Ohm.  Connect the resistors to the capacitor probe and make points at the side of the screen to mark the decrease of the amplitude.  As capacitor probe, use the cables of an old multimeter.  Mount the voltage divider and the BNC jacks into a little box which is directly connected to the second input of the scope. When checking for bad caps, just switch on the signal generator, change to the second channel of the scope and everything is ready.  This method does not give you a direct reading of ESR, but you easily can estimate the ESR from the amplitude of the displayed sinus. The lower - the better.  If you don´t have a signal generator, you could connect a filter to the calibration output of the scope and use this as a source.  The calibration output usually has a lower  frequency in comparison to 100kHZ where ESR is specified, but nevertheless, it should be suitable to identify a bad cap.  I started to use this technique when I did not even know that ESR meters were available and I got used to it.  All I actually do is press two switches and watch the amplitude on the scope as you watch the needle of your ESR meter.  See picture below.

Several years ago, when I was confronted by my first cockroaches, I followed the procedure with the Raid and a garbage bag. When I realized this did not kill them all, I tried something else as I knew I would run into more in the future and I do not want them things around my house!  The next time I came across cockroaches, dozens and in all sizes, I decided to try the freeze method. As cockroaches seek heat, I figured they are probably delicate where cold is concerned.  I took one large dude and placed him in a sealed Bell jar. Next comes the freezer for a 15 minute test. He came out looking dead, but I let him warm up and found he was only dazed.  Next time was a half hour. This time he was very dead!  Now that a time had been established, I was confident of a simple cure.   As I had a fresh, dead one to examine, I went to roll him over with my forceps. I noticed his antenna being attracted to the forceps as they have a slight magnetic charge.   Hmmmmmmm....... cockroaches like heat. Transformers and power supplies give off heat AND magnetic fields. I have come to the assumption they find electronic components by their magnetic fields. (Just a little info for you).  Anyway, the cure?  Plastic garbage bag with the mouth rolled up to the VCR and then taped shut.  In the freezer for 24 hours!!  Never had a live one after that! (It has also never harmed the VCR's).

Use a can of oil spray like CRC 2-23 or CRC 5-56 used in most TV & VCR workshops.