Yamaha CR 620 Distortion Issue

Discussion in 'Yamaha' started by punkzter, Jan 12, 2018 at 1:38 PM.

  1. punkzter

    punkzter Brad

    Messages:
    504
    Location:
    Central Pennsylvania
    I gave my brother a Yamaha CR-620 two or three years ago for Christmas. At the time, it was in good working order with the exception of a popping sound when you turned it off. For better or worse, I made the call to give it to him as-is and told him that if he notice anything odd he should return it and I'd attempt a further repair.

    I replaced all of the lamps and some of the caps on the power supply before I originally sent it off.

    Fast forward to today, and he's noticed that after the unit has been on for a few hours the volume drops and gets muffled/significantly distorted. I believe that it only does this in one channel. It's hard to replicate this, because it doesn't do it every time, and it takes time for this to occur.

    Phew...so an odd problem (at least for someone inexperienced in repair work).

    I have the unit back and would like to start work on it soon. I wondered what some recommended first steps would be. I had considered just doing a wholesale recap...but I've read enough times in this forum that you probably shouldn't do that to solve a problem (you'll likely just create more in the process).

    I did a visual inspection, and it seems fine. But that's all I've got at this point. Any suggestions would be welcomed. (And, if this fixed the popping sound on turn-off, that would be fantastic!)
     
  2. Bert 1100

    Bert 1100 Super Member

    Messages:
    1,139
    Location:
    Planquiri, Switzerland
    I would check the relay for a start. oxidized contacts can explain one channel going after a while, and the popping sound at shut-off could be the relay as well ?
    Just to check, remove the relay, open the top and clean the contacts with a piece of card soaked in deoxit. insert card between contacts, manually close contacts, pull card out.
    If the problem is solved, better anyway change the relay.
     
  3. avionic

    avionic " Black Knights " Subscriber

    Messages:
    37,274
    Location:
    Fort Dodge, Iowa
    95% of the time popping at shut off is caused by a burnt out lamp. Shorted relay driver transistor is another possibility. But if you have a short delay before the relay "click" at power up you can rule out the driver transistor.
     
  4. punkzter

    punkzter Brad

    Messages:
    504
    Location:
    Central Pennsylvania
    I'll take a look at those suggestions, and check back in.
     

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