Metropoulos Forum

I've been looking around for an auto-ranging, in-circuit, meter that will allow me to test for faulty capacitors on various amps and effects. I'm curious what you guys are using and what meters you'd recommend or avoid. Thanks.

There are LCR meters on ePay that are actually very good and they doing their job well. It's 12864 Mega328 Tester. They are sold as PCB only (no enclosure, just working unit) or in plastic white-clear enclosure. It's not a Lab-Quality - High-Precision-Industrial-Standard equipment, but it does the job. I used it to make Inductors for a crossover in passive Speaker Cabinet, cap and transistor testings. I don't think that you need more...
If you want to buy something good, go for a scope. That's the thing that will tell you the whole story. If you'll see a high ripple on a B+ - it really doesn't matter how well or not the cap measures. If it leaky, or it's getting bigger and you see a bubble forming on the top or down of it - it needs to be replaced. Or if it's IC branded it needs to be replaced They are failing so often in fenders... after 5 or so years, they are just dying!

Thank you for the reply. Two more questions.
1) Can you test capacitors in circuit with a scope?
2) Will my old school EICO 460 scope do the job?

Thanks in advance!

You just look with a scope on the filtration that this cap is doing. The amp is working and you see if there is a ripple over DC. If there is - so the cap is bad, most of the time. The thing is that when you working with old tube amps, there always be a ripple in the B+ right before the Choke and after the tube rectifier. So you have to know exactly what are you looking at.
If it's a Solid state amp, and there is no load, and the cap is of a high value (2200uf or more) and you see the ripple there, than you can blame the cap, but once again, depends on a situation. Today I found a bad cap this way on a active speaker

Scope... If that's an old school I'm still in a Kindergarten
All you need a working scope with a 1 meg bandwidth, and a probe 1:10 to look and the B+. Larger bandwidth will show you some high frequency ringing if there is any. If your scope can do that and it's in working condition - use it.
Your scope is a nice piece of equipment. Don't sell it. Make sure that it has a nice brand new caps, good tubes and enjoy! It's an history correct to work on tube amps! That's what they had back than!

I'd love to work with that one, and I'm sure that others on this forum too...

Awesome! Thanks. I'll give it a whirl.