Blue ESR meter and tube equipment servicing

[BubblesTheFish]

Hi,

A few quick General Questions about the Blue ESR meter --

1) I can see where it is very useful for "modern" repairs of solid-state equipment, but do you find real value for tube-equipment repairs? (If so, to what extent). Sure - I can see where you might be working on an old tube tuner and want to check a few of the smaller electrolytics in-circuit, but can you REALLY find problems with the HV caps (400V+) that are more typical of tube equipment?

ie -- I guess what I am trying to determine is how much value an ESR meter has for a mostly tube-equipment technician. Would ~you~ find it a useful tool for tube-equip servicing?

2) To what extent would the ESR meter itself be damaged by dielectric adsorption? As you know, it is not uncommon for a cap, even discharged, to regenerate its voltage. Since you cannot test the cap with a discharge tool attached, I am wondering whether (a) dielectric adsorption could damage the meter, and (b) whether the regenerated voltage (even smaller amounts) would adversely affect the ESR meter reading? My understanding is that the Blue ESR has no ability to safely discharge the cap, and that seems like a limitation.

Thanks in advance,
BtF

[Bob Parker]

Hi,

A few quick General Questions about the Blue ESR meter --

1) I can see where it is very useful for "modern" repairs of solid-state equipment, but do you find real value for tube-equipment repairs? (If so, to what extent). Sure - I can see where you might be working on an old tube tuner and want to check a few of the smaller electrolytics in-circuit, but can you REALLY find problems with the HV caps (400V+) that are more typical of tube equipment?

ie -- I guess what I am trying to determine is how much value an ESR meter has for a mostly tube-equipment technician. Would ~you~ find it a useful tool for tube-equip servicing?

2) To what extent would the ESR meter itself be damaged by dielectric adsorption? As you know, it is not uncommon for a cap, even discharged, to regenerate its voltage. Since you cannot test the cap with a discharge tool attached, I am wondering whether (a) dielectric adsorption could damage the meter, and (b) whether the regenerated voltage (even smaller amounts) would adversely affect the ESR meter reading? My understanding is that the Blue ESR has no ability to safely discharge the cap, and that seems like a limitation.

Thanks in advance,
BtF

Hi,
It's many years since I had a lot to do with tube equipment but I'll try to give some meaningful answers. Tube circuitry tends to put less heat and ripple current stress on electrolytic caps than do solid state switching power supplies and CRT deflection circuits. Also impedances in tube circuitry are generally higher, so capacitor ESR tends to have less serious effects on circuit operation. Personally I never saw a lot of faults caused by electrolytic caps going open circuit until almost everything was solid state, and especially relatively recently as designers put more and more stress on the caps. So I wouldn't recommend dashing out and buying an ESR meter if you only fix tube gear.

The Blue ESR meter can tolerate connection to caps charged up to about 50V. I've seen them connected to more than that without getting damaged. I've never measured what kind of voltage can be caused by dielectric absorption, but I doubt it would be more than 50V.

It's not hard to get hold of a 100 ohm 5W or 10W wirewound resistor and safely discharge any caps which might still be holding a charge. It's a basic safety precaution which I used to do all the time when I was repairing things, but not many technicians seem to be prepared to make that amount of effort these days.

Regards
Bob