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CA-810 Output problems

Discussion in 'Yamaha' started by Rentz, Nov 20, 2018.

  1. Rentz

    Rentz AK Subscriber Subscriber

    Messages:
    342
    Location:
    Texas
    I've been using a Ca-810 i got in barter town for about the past 1.5yrs without much problem but i noticed the occasionally hum in the speakers which came on powerup and went away.
    Flashforward and now the hum is there all the time
    new symptom is now my tape loop outs i used to archive and for a headphone amp are terribly noisy to the point i cannot use them.

    to my knowledge its never been re-capped, i have given it a cleaning out on the inside and used deoxit on the output jacks and the knobs.

    Any suggestions on problem spots to check? I'm not well versed in electronics but my father in law is, as long as its a basic fix.
     

     

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  2. mbz

    mbz Super Member

    Messages:
    2,256
    Location:
    Melbourne, Victoria
    Hums are problematic to solve with many causes. Would be helpful to know if it's mains 50/60Hz or rectified 100/120Hz hum.
    Apparently, there's a mobile phone app that can measure. The sucker bet is to replace the main filter caps, yes, they may be
    the problem but there are many other causes...
     
  3. avionic

    avionic " Black Knights " Subscriber

    Messages:
    44,559
    Location:
    Fort Dodge, Iowa
    A complete power supply recap would probably go a long ways.
     
  4. Rentz

    Rentz AK Subscriber Subscriber

    Messages:
    342
    Location:
    Texas
    Thanks, I’ll see if that’s something I can tackle or maybe just find someone local to overhaul it .
     
  5. Rentz

    Rentz AK Subscriber Subscriber

    Messages:
    342
    Location:
    Texas
    Happen to know the caps to replace ? Or are these the filter caps ?
     
  6. avionic

    avionic " Black Knights " Subscriber

    Messages:
    44,559
    Location:
    Fort Dodge, Iowa
    Know how to read a schematic?
     

     

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  7. avionic

    avionic " Black Knights " Subscriber

    Messages:
    44,559
    Location:
    Fort Dodge, Iowa
    Need to check a couple things first.Very basic stuff.
     
  8. avionic

    avionic " Black Knights " Subscriber

    Messages:
    44,559
    Location:
    Fort Dodge, Iowa
    Unplug the two jumpers on the rear panel. Turn on unit and see if it still hums or if the hum changes characteristics. The removed jumpers will separate the pre-amp from the power amps. And hopefully, eliminate one or the other.
     
    Last edited: Dec 4, 2018 at 5:18 PM
  9. Rentz

    Rentz AK Subscriber Subscriber

    Messages:
    342
    Location:
    Texas
    Don’t even have to try that, it removes the hum so does turning off the preamp or lowering it via the switch
     
  10. avionic

    avionic " Black Knights " Subscriber

    Messages:
    44,559
    Location:
    Fort Dodge, Iowa
    OK that points to the preamp power supply.
     
  11. avionic

    avionic " Black Knights " Subscriber

    Messages:
    44,559
    Location:
    Fort Dodge, Iowa
    C801,802,C805,C806,C807,C808 and C813 These may even show signs of stress.
     

     

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  12. avionic

    avionic " Black Knights " Subscriber

    Messages:
    44,559
    Location:
    Fort Dodge, Iowa
    The hum is both channels. Correct?
     
  13. Rentz

    Rentz AK Subscriber Subscriber

    Messages:
    342
    Location:
    Texas
    Yup it’s on both
     
  14. avionic

    avionic " Black Knights " Subscriber

    Messages:
    44,559
    Location:
    Fort Dodge, Iowa
    Hifiengine has a crappy scan of the service manual. A most excellent HiQ complete copy can be obtained here.
    I highly endorse Normans manuals.
    https://www.analogalley.com/osccart/product_info.php?manufacturers_id=55&products_id=2267

    It will definitely help with disassembly And locating those capacitors I mentioned earlier. Go with the same µf and voltage as what's currently installed in those locations. Personally, I would go with Nichicon UKL's.
     
    Last edited: Dec 4, 2018 at 6:01 PM
  15. Rentz

    Rentz AK Subscriber Subscriber

    Messages:
    342
    Location:
    Texas
    Thanks ! I had the ones from hifienfine and it’s a bit hard on the eyes this one will help
     
  16. avionic

    avionic " Black Knights " Subscriber

    Messages:
    44,559
    Location:
    Fort Dodge, Iowa
    Some of those caps may have dried glue around them. I would remove any dried glue that I would find within the unit. It usually chips off easily with an exacto chisel blade.If any of that glue came in contact with component leads or jumper wires. Inspect for corrosion/oxidation.
     

     

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  17. BobHol

    BobHol Old fart Subscriber

    Messages:
    683
    Location:
    Fort wayne IN
    I had some odd hums from my CA-810. Ended up being from interconnect cables. Straightened them out and no more hum.
     
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  18. avionic

    avionic " Black Knights " Subscriber

    Messages:
    44,559
    Location:
    Fort Dodge, Iowa
    Thats not out of the question either.
     
  19. Rentz

    Rentz AK Subscriber Subscriber

    Messages:
    342
    Location:
    Texas
    one of the first steps i did was changing cables, didnt impact the hum part.
     
  20. jheu02

    jheu02 AK Subscriber Subscriber

    Messages:
    3,133
    Location:
    North Carolina
    All ground wires between boards and grounding screws that attach the boards to the chassis?
     

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