Corroded green contacts on home Amplifier

ZKR

Joined Sep 19, 2011
3
Hello.

Its a Rotel RA-971. Contacts were corroded, right side wasnt working at all.
Gave it to a repair shop, it came back working but the green contacts were still there.
I havent noticed any new parts or repair signs, maybe it was an adjustment issue.
When I asked what parts were replaced and what was the problem, they evaded the question and said its a commercial secret and that they never disclose that, which sounded peculiar to me. He just said "its right side wasnt good and that all you have to know". It also took too little time for them to send it to the main shop and get it back.

My questions are:
1. What could it be to cause the problem.
2. Should corroded (green) contact be replaced and what they would cause if they dont.

Thanks for any suggestions,
Zachary

Last edited:

ZKR

Joined Sep 19, 2011
3

ErnieM

Joined Apr 24, 2011
8,010
Do you mean the tab over the "J87" marking? That looks like a power tab, an external piece of metal to carry a high current that would damage the board underneath. That discoloration is not a problem.

Generally the board looks quite dirty, a good vacuum might help keeping it working longer.

Any shop that doesn't tell me what was repaired gets no more of my business. But if they sent it out they probably don't know either.

ZKR

ZKR

Joined Sep 19, 2011
3
theres also another flat one to the left of 9138.
The issue is also that I didnt pay them yet and want to know if to demand them to renew the contacts. I dont want to sound silly when I make the demand (saying things that are technically rediculous).

The contact you mentioned, I think it exploded once and got partially black when there was a current related issue. The sound then became dirty and the volume weaker. It was renewed.

Joined May 28, 2009
508
The "J" designation usually indicates that it is a jumper. The green coloration is natural when copper oxidizes. If you don't like the green, clean it with some fine steel wool then tin it.

wiskey six

Joined Sep 18, 2011
3
look up verdigree. It is corrosion that take place over time on copper.

SgtWookie

Joined Jul 17, 2007
22,210
I would NOT use steel wool on a circuit board. That's a good way to cause lots of short circuits.

3M's Scotchbrite(tm) pads are abrasive, yet not conductive. They work great for cleaning corrosion from contacts, etc.

bertus

Joined Apr 5, 2008
20,181
Hello,

I mainly use a glass fiber pencil to clean contacts.

Beware the broken pieces of this fiber pen can be itchi.

Bertus

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