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Restore + Repair Yamaha C-2a & C-80 / M-80

Discussion in 'Yamaha' started by mr.muddles, Aug 25, 2018.

  1. mr.muddles

    mr.muddles Active Member

    Messages:
    458
    Location:
    Portland, OR
    Yes, the service manual from hifiengine.
     

     

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  2. clinic-audio

    clinic-audio all on YAMAHA untill 1990

    Messages:
    2,182
    Location:
    France
    This is good :

    C2A-TR.JPG
     
  3. mr.muddles

    mr.muddles Active Member

    Messages:
    458
    Location:
    Portland, OR
  4. clinic-audio

    clinic-audio all on YAMAHA untill 1990

    Messages:
    2,182
    Location:
    France
    How do you want me to test the transistors ? with the right tool (not ohm meter . It will not tell you if the TR is leaking .....Diode meter may be used but it will tell you if the TR is shorted nothing else

    out of circuit if you want to be sure : yes always

    with a diode test ? not good enough for me

    Do you have some new TR ?

    I just have half an hour for you tonight (it is late here)
     
  5. mr.muddles

    mr.muddles Active Member

    Messages:
    458
    Location:
    Portland, OR
    I don't have any new transistors...

    I was waiting to put in my order but I guess the time is now.

    I only have the diode test... some day I will get a transistor checker.

    So I do anything else or wait for new transistors?
     
  6. mr.muddles

    mr.muddles Active Member

    Messages:
    458
    Location:
    Portland, OR
    I rechecked this one and it looks good now...
     

     

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  7. mr.muddles

    mr.muddles Active Member

    Messages:
    458
    Location:
    Portland, OR
    I will get replacements for TR527-530.

    @clinic-audio should I put one pair of good transistors back in the preamp and test it?
     
  8. clinic-audio

    clinic-audio all on YAMAHA untill 1990

    Messages:
    2,182
    Location:
    France
    yes only on the working channel not on the other one (bad)

    most important : stay in stereo do not swith to mono
     
    Last edited: Sep 9, 2018
  9. mr.muddles

    mr.muddles Active Member

    Messages:
    458
    Location:
    Portland, OR
    I had 14 V from TP2 to TP3
     
  10. mr.muddles

    mr.muddles Active Member

    Messages:
    458
    Location:
    Portland, OR
    I think something is wrong...
     
  11. mr.muddles

    mr.muddles Active Member

    Messages:
    458
    Location:
    Portland, OR
    I turned it on again and i thought i heard a spark.... TR527 is getting scorching hot again... -39V
     

     

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  12. mr.muddles

    mr.muddles Active Member

    Messages:
    458
    Location:
    Portland, OR
    using the dim bulb tester... if i touch TR527 the light bulb dims and then glows according to when I touch it...
     
  13. mr.muddles

    mr.muddles Active Member

    Messages:
    458
    Location:
    Portland, OR
    When I touch TR527 it makes like a small rice crispy sound... a small faint pop
     
  14. clinic-audio

    clinic-audio all on YAMAHA untill 1990

    Messages:
    2,182
    Location:
    France
    but TP2 and TP3 is left channel no ?
     
  15. clinic-audio

    clinic-audio all on YAMAHA untill 1990

    Messages:
    2,182
    Location:
    France
    YES ! for sure
     
  16. clinic-audio

    clinic-audio all on YAMAHA untill 1990

    Messages:
    2,182
    Location:
    France
    I think that it is going complicate for you to refix this

    send me a PM
     

     

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  17. asdf_x2

    asdf_x2 Active Member

    Messages:
    168
    Location:
    Finland
    I too just recently got a c2a with similar symptoms, right channel has 37V on testpoints and on stereo right ch has no output (luckily since it would've fried my speakers) and on mono both channels play. I've measured few transistors as of now and at least TR520 or 522 is open. I pulled both and mixed them up. Is it safe to power with these two removed?
     
  18. mr.muddles

    mr.muddles Active Member

    Messages:
    458
    Location:
    Portland, OR
    It's probably best to start your own thread. This one's not really active anymore. I was unable to resolve my issues and sent it to be looked at by a professional.
     
  19. mr.muddles

    mr.muddles Active Member

    Messages:
    458
    Location:
    Portland, OR
    I will update this thread when I've gotten it back and have news of what was wrong. If it can be repaired. (hopefully)
     
  20. asdf_x2

    asdf_x2 Active Member

    Messages:
    168
    Location:
    Finland
    Ok, good luck getting yours fixed.
     

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