Yamaha A-1 Repair and restore: beyond Deoxit

Discussion in 'Yamaha' started by Dadbeh, Jul 2, 2018.

  1. Dadbeh

    Dadbeh Active Member

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    are these choices for replacements ok? specially for the TIP41F im not sure if the choice is sutable.


    TR-133: 2SC1913 -> TIP41F
    TR134 same
    TR135 : 2SA913 -> MJE15033
    TR136: same
    TR137: 2SC1213A - > kSC2383

    S5151 -> no idea, no info i think these are toshiba parts
    S5151R -> no idea
    1S1555 -> 1N4148

    I would like to replace all of these and would appreciate suggestions. all for the A-1 power supply.
     

     

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  2. avionic

    avionic " Black Knights " Subscriber

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    Dual diodes. One is common anode and tne other is a common cathode.
     
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  3. clinic-audio

    clinic-audio all on YAMAHA untill 1990

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    Why do you try to replace everything ? and why looking for TR differents from original type ? Because you don't know where to buy original TR or specific diodes ?

    Why replacing things if they are working ?
     
  4. Dadbeh

    Dadbeh Active Member

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    332
    the power supply board:

    [​IMG]

    glue gone and the two transistors will be replaced tomorrow.

    the green BP cap is in place of a 100 mf 16 volt cap which was not BP. is that a problem?


    ill also do the 0.1 mf metal film caps when they arrive from china.

    edit: in the picture there is a little residue glue left but since the picture was taken, ive cleaned it up more and now other than under the carbon resistors, there is none left that i can see.
     
    Last edited: Aug 8, 2018
  5. amr2

    amr2 Active Member

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    Those green BP are not the most suitable for power supplies...
     
  6. avionic

    avionic " Black Knights " Subscriber

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    Most likely not going to be a problem.
    In PS's. I use Nichicon EP or VP hi-temp bipolars where needed.
     
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  7. avionic

    avionic " Black Knights " Subscriber

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    If they are still serviceable. Leave them alone.
     
  8. Dadbeh

    Dadbeh Active Member

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    i took the nichicon muse BP 16v 85 degrees out and used a 50v 105 degrees instead. same value but 50v is all i have.
     
  9. Dadbeh

    Dadbeh Active Member

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    332
    first board is ready:

    [​IMG]

    [​IMG]
     
    Last edited: Aug 9, 2018
  10. Dadbeh

    Dadbeh Active Member

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    are those transistors correct? TIP41 AND tip42
     
  11. Dadbeh

    Dadbeh Active Member

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    I used TIP41 for 476A
    and TIP42 for 566A

    there has got to be a mistake there. maybe i need to swap the two?
     
    Last edited: Aug 10, 2018 at 9:54 AM

     

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  12. clinic-audio

    clinic-audio all on YAMAHA untill 1990

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    Sorry but why did you replace them if original are working ??
     
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  13. Dadbeh

    Dadbeh Active Member

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    41 and 42 seem to both be npn.
     
  14. avionic

    avionic " Black Knights " Subscriber

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    2SA/B ------ PNP ----- TIP42
    2SC/D ------ NPN ----- TIP41
     
  15. avionic

    avionic " Black Knights " Subscriber

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    Not !!!!
     
  16. clinic-audio

    clinic-audio all on YAMAHA untill 1990

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    ooooh la, la
     
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  17. Dadbeh

    Dadbeh Active Member

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    no it was not working and i coudnt figure it out. also you didnt post the pictures so that i can take the board out and send it to a professional like you to be repaired so i decided to replace all components that i can in the power supply and see how it turns out. i basically tried to follow the steps of mr., yamaha and repalce almost all compoents that he replaced iun his restoration project of 2010. now i am in deep ooooh la la but ill figure it out.
     
  18. Dadbeh

    Dadbeh Active Member

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    upon further inspection, it looks to me like around the emitter of tip 42 the conductor ring around the leg is gone so that it doesn't make a connection. what is there to do in this situation? i only noticed it because realized that the solder joint looks suspect and when tried to reflow i saw that the solder does not stick. removed it and see that there does not seem to be any copper/trace there.
     
  19. Dadbeh

    Dadbeh Active Member

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    yes it was gone. i scraped off a bot of the pcb to expose some copper and connected it with solder. now i have continuity.
     
  20. avionic

    avionic " Black Knights " Subscriber

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    Some of those old boards are getting to the point where desoldering damages the solder pads.
     
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