Testing Caps (out of circuit): What do you use and why?

[gearhead63]

I usually test suspicious caps, especially electrolytics, before I just replace them.
I want to know what is causing a problem instead of throwing parts at it.
Proper diagnosis is the key to EVERY repair.
I have a B&K 801 Capacitor Analyzer and an EICO 950B which is a Wheatstone Bridge type.
The B&K is a quick test, no real high voltages, BUT, you can only test for leakage at 3 volts or 100 volts
which leaves a lot of room for error if you're testing a 450v cap. The EICO is pretty good at finding
leakage, plus you can use it to reform older electrolytics if you want.
So what do you guys use, and why? And just how accurate is it?

[drewl]

Yikes, I remember calibrating Wheatstone Bridges back in the day.

I have a Sencore that can measure caps and coils and resistance if course.
It can put up to 600v on caps and measures leakage and dielectric strength.

[olddawg]

Yikes, I remember calibrating Wheatstone Bridges back in the day.

I have a Sencore that can measure caps and coils and resistance if course.
It can put up to 600v on caps and measures leakage and dielectric strength.

I used to have a big, expensive Sencore Capacitor Checker in a busy shop in which I was the head tech. I finally kept it in my bench area because the knucklehead techs were always accidentally blowing caps up. One setting mistake and a big messy, eye popping bang! A useful tool if you are careful and knowledgable in its use. Everyone had an ESR meter. Honestly... I found that it was more cost effective to simply replace any suspect caps. Caps are cheap. Bench time isn't. If you are restoring collectable amps this strategy may not apply. And even that Sencore would lie to you occasionally when it wasn't splattering paper and chemicals all over the room. Lol.

[Enzo]

Same here. I usually detect a bad cap by its performance in the circuit.

With a few exceptions in the large ones, most caps I encounter cost $3 or less, with non-electrolytics under a dollar. My labor rate is a dollar a minute. By the time I get out a cap tester and characterize some cap, I could have replaced it and moved on. By replacing, I find out if that solved any problem as soon as I fire it up.

Parts are cheaper than labor.

[Chuck H]

You can test caps for leakage in the amp by lifting the leg downstream of the voltage (explanation unnecessary). I don't have a cap tester (other than the value tester on my Fluke). Any suspect electrolytics get replaced. I guess I'm not quite nerd enough for a cap tester If I were to pull what is probably a bad cap for testing I'll just replace it anyway! Having schmancy bench tools is one thing. And it's valid for it's own reasons. Finding a practical use for them is another.