Post by thespianator on Nov 26, 2016 22:33:17 GMT -5
Some time back I got myself a Peak ESR meter with the hope that I could not only locate bad caps IN CIRCUIT, but also see if new caps that I used for replacement were in spec, and check on the sum of film caps I paralleled together for use in crossovers. I know they are usually 20% tolerance, but I like to know the part I'm installing is good.
So when I dragged home a Line 6 Spider II guitar amp (that I got for next to nothing at a garage sale) that would go pop after about 5-6 seconds after turn-on, I decided to look for bad caps, as Chinese caps are typically suspect and I was working on the hypothesis that a bad cap was causing the problem.
With no power applied, I came across a 100uF 10V cap that read 1066uf in circuit, so I thought it was bad. I pulled it, and it read 99uF out of circuit. Scratched my head, then reinstalled it and it read nearly the same 1066uF.
What does this mean? Is there an issue in the circuit that the cap is in? Some caps read open/leaky, and I'm guessing that's due to the circuit it's in. But seeing a reading that's 10 times the rating is confusing.
Thanks!
So when I dragged home a Line 6 Spider II guitar amp (that I got for next to nothing at a garage sale) that would go pop after about 5-6 seconds after turn-on, I decided to look for bad caps, as Chinese caps are typically suspect and I was working on the hypothesis that a bad cap was causing the problem.
With no power applied, I came across a 100uF 10V cap that read 1066uf in circuit, so I thought it was bad. I pulled it, and it read 99uF out of circuit. Scratched my head, then reinstalled it and it read nearly the same 1066uF.
What does this mean? Is there an issue in the circuit that the cap is in? Some caps read open/leaky, and I'm guessing that's due to the circuit it's in. But seeing a reading that's 10 times the rating is confusing.
Thanks!
I've completely recapped a couple of old amps / receivers, and it was a fun project. Eventually I wanted to know how much of what I was replacing actually was bad. I was surprised to find out that there weren't as many out-of-spec caps as one would have suspected given that the receiver was 30+ years old. I still shotgunned the whole thing.
