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Yamaha C2A preamp: another thread about crackling and popping

Discussion in 'Yamaha' started by lowredmoon, Apr 3, 2017.

  1. sonavor

    sonavor AK Subscriber Subscriber

    Messages:
    268
    Location:
    Texas
    I understand and agree with your suggestion. I follow that same process on my restorations. I don't change out components like semiconductors unless they are obviously bad. The majority of problems I have encountered are solder joints (especially on connectors) and electrolytic capacitors. I will definitely start with those first. I was just looking ahead and preparing for the worst when I noticed that the transistors Adam mentioned aren't carried by my usual suppliers (Mouser, Newark and Digikey).

    Thanks for the information on resistors. That was enlightening to learn.
     

     

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  2. lowredmoon

    lowredmoon Active Member

    Messages:
    148
    Location:
    Central Pennsylvania
    What is the watt rating for the adjustment pots? Is it acceptable to use multi-turn?
     
  3. lowredmoon

    lowredmoon Active Member

    Messages:
    148
    Location:
    Central Pennsylvania
    I bought mine from Mouser a couple months ago. They may be out of stock now. I have a couple extra, but not too many, if you find you need them. Their gain is about 40% higher than the originals.
     
  4. lowredmoon

    lowredmoon Active Member

    Messages:
    148
    Location:
    Central Pennsylvania
    After resoldering all joints and replacing all of the electrolytics (many tested poorly and were bulging out), the noise floor has dramatically improved. The bias, DC offset, and power supply voltage stay within range.
    There is still intermittent "popping" coming from each channel, but not at the same time.
    I'm going to use my scope to find where it is originating. Because it is intermittent, it may take some time to find.
     
  5. avionic

    avionic " Black Knights " Subscriber

    Messages:
    44,701
    Location:
    Fort Dodge, Iowa
    Did you check out those resistors . That Patrice(clinic audio) was referring to ?
     
  6. lowredmoon

    lowredmoon Active Member

    Messages:
    148
    Location:
    Central Pennsylvania
    I visually inspected them all with a flashlight and magnifying glass. I didn't find any cracked ones, but that doesn't mean they're all good. I'm going to try to isolate the source, or close to it, tonight.
     

     

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  7. clinic-audio

    clinic-audio all on YAMAHA untill 1990

    Messages:
    2,219
    Location:
    France
    Hello

    I'm going to use my scope to find where it is originating. Because it is intermittent, it may take some time to find.
    Yes , but take a freeze spray to go faster and step by step you will create the noise more quickly

    In my point of view , your trouble is coming from the long board at the front of the unit but difficult to confirm without the unit in front of me
     
  8. lowredmoon

    lowredmoon Active Member

    Messages:
    148
    Location:
    Central Pennsylvania
    Does cooling the components cause the fault to occur more often?
     
  9. clinic-audio

    clinic-audio all on YAMAHA untill 1990

    Messages:
    2,219
    Location:
    France
    Yes of course
    And it is a good idea to use a cylinder to blow a concentrate "jet"
     
  10. lowredmoon

    lowredmoon Active Member

    Messages:
    148
    Location:
    Central Pennsylvania
    Ordered.
     

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  11. clinic-audio

    clinic-audio all on YAMAHA untill 1990

    Messages:
    2,219
    Location:
    France
    I personally use -70°C but -51°C is fine
     

     

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  12. lowredmoon

    lowredmoon Active Member

    Messages:
    148
    Location:
    Central Pennsylvania
     
  13. lowredmoon

    lowredmoon Active Member

    Messages:
    148
    Location:
    Central Pennsylvania
    I can change my order.
    You have experience, and if the colder rated spray is more effective, I'll get it instead.
    What brand (s) are rated -70?
     
  14. lowredmoon

    lowredmoon Active Member

    Messages:
    148
    Location:
    Central Pennsylvania
    This one claims -65C.
     

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  15. clinic-audio

    clinic-audio all on YAMAHA untill 1990

    Messages:
    2,219
    Location:
    France
    Products depend of your location (country) but don't worried -65° will be fine !
    All you have to do is a thermal chock . This will make the trouble "on" and you will not wait hours after it
     
  16. lowredmoon

    lowredmoon Active Member

    Messages:
    148
    Location:
    Central Pennsylvania
    I ordered it. Thank you for your help!
     

     

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  17. sonavor

    sonavor AK Subscriber Subscriber

    Messages:
    268
    Location:
    Texas
    Have you made any progress on the c2a preamp problem?
     
  18. lowredmoon

    lowredmoon Active Member

    Messages:
    148
    Location:
    Central Pennsylvania
    Not yet. I'm in the middle of a house move and working 12 hour days, so all fun is on hold for what I hope is only another week or two. I haven't given up on it, and will post again when I resume the project.
     
  19. karlsartori

    karlsartori New Member

    Messages:
    1
    i have a c2a and the same problem arose for me.i had a tech attempt to repair but popping and crackling continued ,i use MC setting, so I purchased a Yamaha HA-1 moving coil head amp which operates through the c2a moving magnet setting and the problem disappeared completely.i can only assume that this problem with my c2a is with the MC circuitry.just a thought.
     
  20. avionic

    avionic " Black Knights " Subscriber

    Messages:
    44,701
    Location:
    Fort Dodge, Iowa
    Noisy transistor or diode in the MC amp.
     

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