A-1000/A-1020 info/repair thread

Discussion in 'Yamaha' started by OMGCat!, Aug 18, 2015.

  1. mhjmhjones

    mhjmhjones Active Member

    Messages:
    287
    Location:
    Delaware, USA
    That is a great help, thanks James. I had a service shop diagnose the amp and they said three of the transistors were bad and the estimated it would be $250 to replace them all. So, I'm considering doing it myself!


     

     

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  2. mhjmhjones

    mhjmhjones Active Member

    Messages:
    287
    Location:
    Delaware, USA
    How many of each transistor does one need? I'm guessing eight (8) each of the first two listed?
     
  3. Bratwurst7s

    Bratwurst7s In The Frying Pan Subscriber

    Messages:
    4,000
    Location:
    Munich, Germany
    4 each of the 2SA1265 (PNP)/NJW0302G and 4 each of the 2SC3182 (NPN)/NJW0281G. They are arranged with 2 of each type (NPN/PNP) per channel.

    1 of each type (NPN/PNP) of the drivers for each channel for a total of 2+2.

    Normally one would expect that if 3 of the outputs are bad then there will be other damage as well, drivers, resistors etc.

    Cheers,
    James
     
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  4. OMGCat!

    OMGCat! AK Subscriber Subscriber

    Messages:
    2,873
    Location:
    El Sereno, CA
    I agree with James both with his parts recs and in saying it will likely need some additional parts replaced.

    Look around the bad channel for any of those standing up green resistors and see if the have a brown or burned band around them. They are fusable and will open up. Sometimes the damage is hard to spot and looks very much like a color band so a magnifier may be of help.
    Those you can replace with flame proof carbon or metal films.

    Also check the other channel for loose or cracked solder joints. My driver transistors were completely loose in their board along with many other cracked joints. Again, magnifier is helpful here.
     
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