Started restoration on my CA-810 !

Discussion in 'Yamaha' started by Bert 1100, May 16, 2017.

  1. Bert 1100

    Bert 1100 Super Member

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    I always wanted one of those, and when one came up on our local auction site, I had to get it...
    It came in one piece despite a poor packing job, and it was working well, but with the usual contact noises and such.
    What is not so nice is the smell that it gave off, a mixture of tobacco and moldy / old house smell...

    So a big part of the job will be cleaning !

    It will get all new caps, a new relay, leds and whatever else it needs...

    This is how I received it, it looked pretty good, I think it had gotten a good cleaning of the exterior.

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    The insides were another story !

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    first : dismantling, so I can give the whole thing a goooood wash !
    The relay came out, and of course the transformer will not get wet.
    That transformer is HEAVY ! just above 5 kilos !

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    I'm getting rid of all those sticky and stiff PVC sleeves, me no like...
    So, a good wash in the sink !

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    drying in the oven at 70 degrees C.

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    Out in the sun.

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    Look at the solder joints of the regulators....

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    The relay contacts don't look good....I have a new relay.

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    This project will be quite slow, I'm doing a Marantz 2325 at the same time :confused:
     
    Last edited: May 16, 2017
    Karl vd Berg, smurfer77 and amr2 like this.
  2. Mr. Yamaha

    Mr. Yamaha Not so much Yamaha lately... Subscriber

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    Great work :thumbsup: I will follow this, I have a CA-810 to redo myself :naughty:
     
  3. amr2

    amr2 Active Member

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    Great work!! :beerchug: Changing the bias trimpots could be also a good idea.
     
  4. Bert 1100

    Bert 1100 Super Member

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    Thanks !
    About the trimpots, I'll have to see, because the originals are accessible from the trace side of the PCB through a small hole...but yes having new multi-turn pots would be nice....
     
  5. amr2

    amr2 Active Member

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    Or you can use a good single turn trimpot (I like Bourns cermet)
     
  6. SuperLead100

    SuperLead100 "These go to 11"

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  7. Bert 1100

    Bert 1100 Super Member

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    I took some time to work on the CA-810 last weekend :

    phono board recapped, all Silmic II

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    New main filter caps and new fast/soft recovery diodes.
    The Kemet filter caps are the same diameter as the original but are 5mm taller (75mm), they leave just 1mm of clearance with the control shafts.
    They are 15'000uf / 63V
    Their pin-out is slightly different from the originals and required a bit of adapting the PCB.


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    Last edited: May 29, 2017
  8. SuperLead100

    SuperLead100 "These go to 11"

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  9. Oldsansui441

    Oldsansui441 AK Subscriber Subscriber

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    Nice neat work with the filter caps :thumbsup:.
     
  10. Bert 1100

    Bert 1100 Super Member

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    Got quite a bit more done this weekend :
    recap is 100% done, also did the secondary P.S. diodes.
    All the transistors with heatsinks got taken off the board, fresh thermal paste and cleanup of the glue.

    There was a little surprise in the tone board : C330 (10uf 25V) was factory soldered in with the polarity wrong !7This is a signal coupling cap, I'm not sure what the effect on the sound was........anybody knows ?
    And yes I'm quite sure, the schematic and board drawing and silkscreen all show the same proper way, and this circuit is nice and symmetrical for both channels...

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    I cut out some of the bottom of the hot regulators heatsinks, this should give some more airflow and keep them a bit cooler.

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    more pics....

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    After having given the output transistors fresh thermal paste, the heatsinks are coming back together

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    Did some cleaning as well, and could not resist shining up the top cover of the function board and the selector shafts.
    Useless but I like things looking good inside as well :D

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    I will soon put the transformer back in....I'm a bit nervous here because normally I would do one board at a time, and test in between......
     
  11. zaibatsu

    zaibatsu Active Member

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    Very nice and neat. :)
     
  12. Mitkraft

    Mitkraft AK Subscriber Subscriber

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    Great thread! I have non working CA-2010 on the to do list and threads like this are a great help both to gain more info but also to remind me I might still have more to learn before I can tackle it.
     
  13. amr2

    amr2 Active Member

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  14. amr2

    amr2 Active Member

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    btw, If you are resolding joints be careful with the styrol caps. These caps are heat sensitive.
     
  15. Bert 1100

    Bert 1100 Super Member

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    Yes, thank you. I will not touch them anyway....

    Thank you :)
     
  16. OMGCat!

    OMGCat! AK Subscriber Subscriber

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    Very nice work! I think you will give some people a heart attack cleaning it like that but I've done it myself with great results.
     
  17. Mitkraft

    Mitkraft AK Subscriber Subscriber

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    Are the transformer and relay the only things you took off the boards before washing them?
     
  18. Bert 1100

    Bert 1100 Super Member

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    Yes, that's right.
     
  19. Bert 1100

    Bert 1100 Super Member

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    Spent some more time with the CA-810 this weekend.
    The transformer is back in...testing with the "main in" with the function board still out, I only have the right channel, nothing on the left...:eek:

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    A quick look around, and I found that the minus lead for the left channel had broken off the lights PCB...so that was fixed, both channels are working well.

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    With the function board in, all functions are working properly :banana:.

    I start checking the idle current, both channels adjust easily to 20mV, BUT I see the current sometimes shooting up (from 20 to 50, 100 or more...) on the right channel then settling back down....OOOOPS :eek:. With the DBT in line I see this happens when I press on the trimpot in a certain way...
    So I've ordered some 1-turn Bourns 2.2K trimpots, I'll see if I can mount them on the bottom side of the board, There is quite a bit of space there.
    I hope the trimpot is what is causing this instablity, I checked everything in the area and did not see anything suspect.

    I added some bent bits of solid wire so the DMM leads can get a good grip at the idle check points.

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    Also the meters are back in. I don't recommend taking them off, they are glued in place and you don't know how the very thin and bendy aluminium plate with "left" and "right" will come off (it can stay on the meter, or on the faceplate, or half-half.....)
    But one of my meters was glued in crooked from the factory, so I took the risk and it worked out well.

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    More news after I replace the trimpots !
    It looks like you were right !
     
    RedSquare likes this.
  20. Bert 1100

    Bert 1100 Super Member

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    Oh, and I'm measuring 20 and 25 mV DC at the speaker terminals, not too shabby, but I will be changing the diff pair transistors as well. Originals are 2sa872, will be changed to ksa992.
     

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