Re: Harman/Kardon AVR5500 (AVR520)

Measured the C481 cap when turning on the amp. The cap charged up to 50V but when protect turned on it slowly discharged withing 30 sec. The C481 cap stays at 50V. So I guess it's something shorting?

The plus side on the C481 cap is feeding the transistors and VCC out to 2 different terminals. The negative side is common to both caps so my guess it must be something down the line on the + side?

How to you check transistors in a good way?

Re: Harman/Kardon AVR5500 (AVR520)

Thank you for your respond!

Was thinking to check that too. But was also thinking how could the other cap be charged up if the recitifier is bad? The C481(10000uF) capacitor is connected to the + on the rectifier. The C481 and C482(10000uF) is connected together with the ground and the otherside of the C482 is connected to - on the rectifier.

Could it be something further down the line that is grounding the C481 cap so it's getting discharged?

Hello, I'm sad

When I turn on my AVR 5500 it shuts off immediately. According to the previous owner it only turned off occasionally. For me it never worked. So I opened it and saw the big 10000uF caps where bulging so much it lifted of the board and separated the glue. So I order all new Nichicon electrolytic caps for the front and the surround amp boards. Also replace te caps on the small board that have the small transformer. After I replaced them I have the same issue.

One thing I noticed when disassembled I had 50V on one of the 10000uF cap but the second was...

Re: New Members - please post your introductions here

Hello!

I'm guy from Sweden that like to fix vintage and newer electronic. Found really good information on this site so I joined to get better access to picture and so on.

Have a good day guys and girls!