CR-420 right channel issues

Discussion in 'Yamaha' started by JPromo, Dec 31, 2017.

  1. JPromo

    JPromo New Member

    Messages:
    18
    I love my 1020, so I picked this up recently for a second receiver. Fully tested upon getting home and the right channel only output distortion, not even distorted music, just buzzes to the beat.

    Thorough de-oxit didn't fix it. Needs caps, but I wouldn't think caps would cause that dramatic of a distortion.

    Output transistors tested no shorts. Then I was checking voltages on the OTs and.. slipped, shorting one left channel momentarily. Suddenly both channels came in clear. It played perfectly for maybe 10 minutes, then quickly degraded back to where it was with the right channel distorted.

    So, what could this be? I'm familiar with the grounding issues on these CRs, so I will start there, but any other thoughts? Thanks!
     

     

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  2. avionic

    avionic " Black Knights " Subscriber

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    Possibly cold solder connection somewhere on that amplifier assembly.

    PS get yourself some mini-grabber test leads. To minimize test point slippage and burnt up components.
     
  3. avionic

    avionic " Black Knights " Subscriber

    Messages:
    40,701
    Location:
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    Tap on the protect relay and listen for audible changes to the effected channels.
     
  4. JPromo

    JPromo New Member

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    18
    Amen. I just get excited when I get a chance to tinker on something.

    On the other hand, the fact that it jolted itself into working temporary eliminates some possibilities.. I will check for cold solder when I get under the board.
     
  5. JPromo

    JPromo New Member

    Messages:
    18
    I just fired it up and it's good again. Tapping on the relay did not cut it out. I will rap it again when the issue returns.
     
  6. JPromo

    JPromo New Member

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    Next time the channel cut out, I knocked the relay a few times and my right channel came back. Any special way to clean it? The lid looks like it can be popped off.

    Thanks for the suggestion, avionic!
     

     

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  7. avionic

    avionic " Black Knights " Subscriber

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    Replacement is prefered remedy.
     
  8. avionic

    avionic " Black Knights " Subscriber

    Messages:
    40,701
    Location:
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  9. JPromo

    JPromo New Member

    Messages:
    18
    Fujitsu FRL-264 d024/02ck

    Seems that's 24v. Would your linked relay be suitable, or would it be best to track down an NOS one? I'm already putting a mouser order together, so that would be great if it would work. The footprint looks right. Thanks again for the help.
     
  10. avionic

    avionic " Black Knights " Subscriber

    Messages:
    40,701
    Location:
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  11. avionic

    avionic " Black Knights " Subscriber

    Messages:
    40,701
    Location:
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    No..
     

     

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  12. Chaulk61

    Chaulk61 New Member

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    I have the same issue on my 420.....channels cut in and out when tapping on the relay. However, on mine , it does the same thing when using headphones. Does this rule out the relay as the problem?
     
  13. avionic

    avionic " Black Knights " Subscriber

    Messages:
    40,701
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    Nope...
     
  14. avionic

    avionic " Black Knights " Subscriber

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    40,701
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    Look at the schematic. You will see that the headphones and speakers binding posts are both after the relay.
     
  15. Electone

    Electone Well-Known Member

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    Location:
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    Replacement is always the best solution, but if you need a temporary fix, soak some thick paper in Deoxit and drag it through the contacts of the relay. You'll be surprised how much gunk comes off. The problem is that the contacts become pitted and dirty after time. The dirt can be cleaned, but the pits need to be sanded down - better to replace at that point.
     
  16. avionic

    avionic " Black Knights " Subscriber

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    Theres always the remote chance of a bad solder connection on the relay or in close proximity to the relay.
     

     

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  17. avionic

    avionic " Black Knights " Subscriber

    Messages:
    40,701
    Location:
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    carbon
     
  18. Chaulk61

    Chaulk61 New Member

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    17
    Thanks avionic and electone......a new relay is on its way.
     
  19. Chaulk61

    Chaulk61 New Member

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    17
    New relay arrived......soldered it in.....I am currently listening to two clear channels....woo hoo ! Thanks again for the help on my first repair
     
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  20. avionic

    avionic " Black Knights " Subscriber

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    Excellent!
    Dropped right in. Didn't it.:thumbsup:
     

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