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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    Planquiri !
    Thank you ! And yes, the CA-810 is definitely worth it !
     
  2. Oldsansui441

    Oldsansui441 AK Subscriber Subscriber

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    Nice work on the speaker terminals, they look great.
     
  3. Roboturner91

    Roboturner91 AK Subscriber Subscriber

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    My 810 has the same transformer hum, especially on startup. Like an overdriven guitar with the whammy pedal all the way down. It's barely noticeable after the first 5-10 seconds after powering on but still worries me a bit.

    I'm also inspired here, great job with the IEC mod and speaker terminals. I'd like to do LEDs on my meters someday but that's probably a little above my head at the moment.
     
  4. SuperLead100

    SuperLead100 "These go to 11"

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    Excellent work, it was well worth the watch and wait. It must be very satisfying to successfully accomplish a task like that!
     
  5. Bert 1100

    Bert 1100 Super Member

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    The amp has been in use on and off, it has seen maybe 1 month of everyday use.
    Lately I noticed the meter lighting has become dull and with a cold light color.
    So I opened the light housing and saw that all four of my leds, the warm-white 5mm "straw-hat" were all very dim and blueish :rant: :idea:
    I'm not sure what happened here, those leds have a nominal current of 20mA, and that's the number I got with choosing dropping resistors.
    At first I thought I had forgotten they are in series and that I had given them 80mA for the 4 of them, but no.
    They are in series, so the current in the circuit is the same for all 4, at 20 mA....

    So I put in other ones I had, 3mm bright warm-white, with the top sanded off for more diffuseness. And the nice warm even light is back.
    I hope those will last longer...or maybe I should hope I did something wrong, since I used the same ones for a Marantz 2325 (function lights) I did for somebody :confused:

    Does anybody see if I did something wrong here that would explain the leds going bad ? Maybe it's getting too hot in there ? Most likely not.
     
  6. Mr. Yamaha

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

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    Did you increase the large 5 Watt resistors to limit the current to the correct value? I believe there's 75 or 80 Volts on it, so the current needs to be dropped with increasing those large resistors. I replaced those in mine and the LED's are fine for almost 2 years.
     
  7. Bert 1100

    Bert 1100 Super Member

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    Yes, the resistors were changed (there are two of them for the 4 display lights, unlike the schematic which shows one).
    When I do the swap to leds, I start with a high value resistor and monitor the current, changing the resistor to get the proper current.
    Here I now have a total of 3.6 kOhm resistance, gives me 20.5 mA cuurent, the leds are rated nominal 20mA, max 30mA.

    At first I thought I did something wrong, what else could cause all 4 leds to go bad ? But now I've realised maybe there was just one bad led in the lot that caused the current to drop to the other 3, since they are all in series...
    I did not dispose of the "bad" ones yet, maybe I can check if it is just one that has gone bad.
     
  8. Karl vd Berg

    Karl vd Berg Super Member

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    Awesome work, Bert! :trebon:
     
  9. dksp

    dksp Active Member

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  10. Bert 1100

    Bert 1100 Super Member

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    Hmmmm ça c'est intéressant...
    I'll leave the amp in use and report back if there are problems with the new leds. I wonder what is happening here.
    What was your source for the straw-hat leds ? Mine were from bright-components.co.uk
     
  11. dksp

    dksp Active Member

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    I got mine from chinese seller on eBay. Probably you got the same make.

    I did the LED conversion in order to avoir changing bulbs every 1-2 years… it missed.
     
  12. Willy6

    Willy6 AK Subscriber Subscriber

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    What did you use in place of those 2.2uf 25v bp caps on the protection circuit?
     
  13. Bert 1100

    Bert 1100 Super Member

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    As Willy mentions, these are BiPolar, the KL or PW are not bipolar.
    I think I used Wima MKS2 film caps (the red square ones)
    Panasonic ECW or ECQ will also be fine but they are bigger.

    There is a 10uf 50V bipolar somewhere there also, I used a Nichicon Muse ES (the green one you can see)
     
  14. Willy6

    Willy6 AK Subscriber Subscriber

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    Ya I saw the green nichicon muse ES in your pics but I wasnt sure what the red square ones were.Did you use the Wima MKS2 anywhere else in this amp?
     
  15. Bert 1100

    Bert 1100 Super Member

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    Yes I did, any electrolytic of 2.2 uF and below was replaced with these film caps. All in all nine 1uf and four 2.2uf if my list was correct :D
     
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  16. Willy6

    Willy6 AK Subscriber Subscriber

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    Was that only the bipolar ones or can I use them in place of the polarized variety?
     
  17. Bert 1100

    Bert 1100 Super Member

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    Yes, here all small electrolytics can be replaced by a film cap.
    But of course size and price goes up very quickly once you go above a few uF...
     
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