Corroded green contacts on home Amplifier

Discussion in 'Wireless & RF Design' started by ZKR, Sep 19, 2011.

  1. ZKR

    Thread Starter New Member

    Sep 19, 2011

    It`s a Rotel RA-971. Contacts were corroded, right side wasn`t working at all.
    Gave it to a repair shop, it came back working but the green contacts were still there.
    I haven`t 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 it`s a `commercial secret` and that they never disclose that, which sounded peculiar to me. He just said "it`s right side wasn`t 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 don`t.

    Thanks for any suggestions,

    Last edited: Sep 19, 2011
  2. ZKR

    Thread Starter New Member

    Sep 19, 2011
  3. ErnieM

    AAC Fanatic!

    Apr 24, 2011
    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 likes this.
  4. ZKR

    Thread Starter New Member

    Sep 19, 2011
    there`s also another flat one to the left of 9138.
    The issue is also that I didn`t pay them yet and want to know if to demand them to renew the contacts. I don`t 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.

    Thanks for replying.
  5. radiohead

    Active Member

    May 28, 2009
    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.
  6. wiskey six

    New Member

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


    Jul 17, 2007
    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.
  8. bertus


    Apr 5, 2008

    I mainly use a glass fiber pencil to clean contacts.


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