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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    Thank you ! And yes, the CA-810 is definitely worth it !
     

     

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  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.
     

     

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  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.
     

     

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  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?
     

     

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  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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  18. Bert 1100

    Bert 1100 Super Member

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    So, reporting back as promised :)
    The second set of leds I installed also started fading out with a greenish tint within a dozen hours of use.
    I'm not sure what's going on, since the current going through was measured at 20mA, nominal for these leds...

    So what I did is this : I added a THIRD led for each meter, by inserting the legs in the existing rubber grommets, and cutting the trace at the back. seee photos.
    I then cut down the current to 9mA, with two 3.6kOhm resistors (in series here)
    It looks just as good and as bright, I hope it will last longer like that.....

    IMG_4277.JPG

    IMG_4278.JPG

    IMG_4279.JPG

    IMG_4281.JPG
     
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  19. Bert 1100

    Bert 1100 Super Member

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    Another thing that annoyed me from the start with this amp was the (mechanical) buzzing from the transformer. The whole amp was vibrating slightly and the hum could be heard easily from my listening position.
    So I thought, what the hell, what does one do to get rid of vibration ?
    Here is my solution, and it works wonderfully well, a tiny buzz only is heard when you put your ear right on top of the cover, within a few centimeters of the transformer.

    I would NOT recommend this if you plan to ship the amp at any time, since the transformer can move around slightly, and a hit could send the heavy thing to damage something within it's range of movement...

    4 silent-blocs, diameter 8mm, length 15mm. The secondary metal plate beneath the transformer was taken out. Like this there are still a few mm clearance to the top cover.

    Not being sure of the consequences of the transformer case not being grounded anymore, I ran a wire to keep the ground.

    IMG_4274.JPG IMG_4275.JPG IMG_4276.JPG
     
  20. Mr. Yamaha

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

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    Great, thanks! The transformer of my CA-810 is also humming loudly. I will try this!

    About the LED's: I have exact the same problems with diffuse LED's in my B-2 and CA-810. Running respectively on 15 mA and 20 mA. They start to fade slowly and are completely dull after a month's use. I went back to the seller and he said that while you limit the nominal current, the peak currents in 'vintage audio gear' can be much higher. These peak currents would only be visual with a scope. So he said. Apparently these LED's can't handle those peak currents and will die. I'm not sure about his story.

    I use LED's from led1.de for years in my gear (sometimes even at 25 mA) and they never fade, even after years of use.

    So I think there might be differences in quality ;)
     

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