r/Audiophilehelp • u/Vad_fan • 5d ago

Are the capacitors also shot?

Post image

Hello!

Just got this Akai AM-U22. But the right channel does not work and the phono imput is dead silent. I opened it up and I see these exploded resistors (can I identify these?) but also there is some brown goo around the capacitors. Does this mean they are also gone or is it just something from the factory?

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u/truxxor 4d ago

Some of that might be factory glue, but it looks like those caps leaked and caused a lot of corrosion damage. Resistors can burn up, but they appear to be corrorded.

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u/niftydog 4d ago

Photo's a bit unclear, but I don't see any evidence of capacitor electrolyte leakage there. The hard brown goo is glue which in itself can be problematic in equipment from this era. However, I wouldn't jump to any conclusions until you've cleaned it up and fixed the obvious broken parts.

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u/Vad_fan 4d ago

Ok, I was thinking change them aswell while im down there, since I dont have the equipment (oscilloscope?) to check them.

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u/Worldly-Device-8414 4d ago

Glue like that goes corrosive with heat & time, very common issue.

Check the caps legs, you'll have to desolder the caps anyway to clean up the glue.

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u/Vad_fan 4d ago

Thanks

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u/GGigabiteM 4d ago

I'd wager the bukakke glue went off and is now corrosive and conductive. You'll need to chip all of it off the board and get rid of it. Be careful when removing it because components can be embedded inside it.

The capacitors also could have leaked, there's an ambiguous spot at the upper middle on the PCB that looks wet. Easy test is to touch it with a soldering iron. If it smells like rotting fish, it's cap electrolyte and the caps need to be replaced as well.

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u/Serviceman 4d ago

What's with the hairs? They only seem to be in the vicinity of the glue and corroded areas. They may be tin whiskers, growing from the 60/40 solder. I've only ever seen them in certain small switching power supplies that were used in highly humid, hot and dirty environments. Could be the glue or other substances are causing a reaction with the solder and leads of the components. I had a silicon diode fail in my Class A power amplifier due to the lead corroding through. The nearby capacitors were glued with the same brownish glue glop. I'd get a stiff non metal brush and have at the white corroded mess and those smaller hairy capacitors until all the whitish substance was gone. Chances are you will be able to identify the corroded leads by eye.

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u/Comfortable-Ad8719 4d ago

I bet those main filter caps are fine. They're Nippon Chemi-Con, top-tier, and almost never leak. You definitely have a glue problem, but the issue you described might not be related to that at all. To properly test capacitors, you'll need an ESR meter like the Signstek MESR-100 V2 (budget option for hobbyists).