Capacitor Leakage question

[nosaj]

What is an acceptable level of capacitor leakage? I've got a few in a deluxe reverb that are showing about .05 vdc and .6vdc.

Thanks,
nosaj

[Mick Bailey]

Depends where the cap is and the type. If it's a PSU electrolytic, you probably wouldn't notice it. If it's a coupling cap then it will skew the bias of the following stage. 0.6v pretty much halves the bias voltage in a typical 12AX7 stage. If you're measuring the leakage with just DC present, bear in mind that when passing AC the underlying DC leakage can increase and be much worse. A cap that passes DC is a failing component and won't get better.

[Leo_Gnardo]

What Mick said ^^^. And 1) no guarantee the DC leakage will be constant, it could be random causing crumbling rumbling noises, sizzle, pop, squeeks etc. Furthermore B) if it's a cap bringing signal to an output tube, will increase the bias current of that tube, also noises with or without signal, and eventually it will leak more driving your output tube into red plate failure. Then the noise will be the crinkle of cash leaving your pocket to replace tubes & caps, also the familiar refrain "why didn't I fix this earlier???"

A cap that passes DC is a failing component and won't get better.

+ 1000 ! Truer words were never typed.