Crate GX-1200 - Problems persist after new parts

[skidmark]

My schematic says it's a 2.2. As for my question I should have been a bit more detailed.
My question was not about value but type. Like film, polymer, aluminum, stay with electrolytic?
I've been reading up this evening on why designer even use electrolytics for audio coupling.
Al

[DrGonz78]

Aluminum generic everyday ordinary electrolytic capacitors are just fine. Don’t redesign while fixing. Fix first then play around with it.

[The Dude]

Nothing special about C25, IMO. Just use something with the same parameters and that checks good. If I didn't have one handy, I'd probably just rob one from one of the several scrap boards I have laying around.

Also, FWIW: An ESR meter won't tell you if a cap is leaky. In fact, a nearly shorted cap will test great ESR. Just touch your ESR meter leads together and you'll see what I mean. You need a cap tester that actually tests leakage to show you if leakage is a problem. Or, often times and as you did, you can see it with DVM resistance measurements.

[skidmark]

Well your right. The Peak ESR tester will miss leaks. I really should have thought that through more. It has a 12 volt battery in it.
An assumption I won't make again!.

Al

[DrGonz78]

The thing is an ESR does come in handy but you first need to just observe its behavior when it reads questionable caps. I can spot some no brainer bad caps with one pretty accurately but it’s more from my experience than the meter. My ESR tester, just this week, quickly found 5 caps that were bad. 3 of them caused an error and 2 read really high leakage at low voltage. All were 1975 made in Mexico and dead as could be. The mains filter caps are Mallory USA and they measure good. I am still getting rid of them cuz they are beginning to vent. Don’t depend on them to be a fortune teller but they are useful still.

[skidmark]

Good advice, thanks!
Al

[g1]

Once again, the cap is not the source of the problem and that still needs to be located. So replace it and find out where the DC is coming from. IC5 pin1 should not have any DC. Do you measure any there?
If no DC at + end of C25, then there should be none on the other (-) side.

As far as the cap value, the schematic you shared with us (first post) shows 1uF. Where are you getting the 2.2uF from, are you using a different schematic?

[DrGonz78]

G1 has good questions to answer. In the meantime since we were talking about my ESR testing. I took a few pictures of capacitance and ESR. Cap value should be 150uf. One bad cap won’t read on ESR and another will read but it shows like 67 and very leaky, also it reads like 76uf. The one that doesn’t read on the ESR meter reads 115uf or something. It’s reading better than the one that it can read. A good brand new cap on the ESR meter measures 0.2. Also when you test the capacitance a bad cap it often charges up very slowly.

[The Dude]

......One bad cap won't read on ESR and another will read but it shows like 67 and very leaky....

I don't understand the "very leaky" part of this. How did you measure leakage? I don't see any leakage measurement device in your pics. Or, you mean the cap had some obvious measured DC resistance?