recapping sx-850 for my son

Discussion in 'Pioneer Audio' started by nackesww, Mar 22, 2018.

  1. nackesww

    nackesww Member

    Messages:
    96
    Location:
    New Auburn, Wisconsin
    13. -12.91
    14. -49.52
    15. -17.41
     

     

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  2. nackesww

    nackesww Member

    Messages:
    96
    Location:
    New Auburn, Wisconsin
    Sweet!!! Thanks 1mego!! Wish you were closer i would take you out for a steak dinner.
     
  3. 1MEGΩ

    1MEGΩ Active Member

    Messages:
    184
    Location:
    Mamou, Louisiana
    Just a little low, but much better and should be just fine. Is it playing now? Other problems?
     
  4. nackesww

    nackesww Member

    Messages:
    96
    Location:
    New Auburn, Wisconsin
    Relay isnt kicking in. I was going to check the protection circuit next.I'll put that off until tomorrow. I've been on this since 7:00 this morning.
     
  5. nackesww

    nackesww Member

    Messages:
    96
    Location:
    New Auburn, Wisconsin
    I'll post the pin measurements of the protection board, then i need to get something to eat. :)
     
  6. 1MEGΩ

    1MEGΩ Active Member

    Messages:
    184
    Location:
    Mamou, Louisiana
    Very good.I'll see if I can help you with this tomorrow. The steak idea was very nice. You never know, it is really a small world. Thank you.
     

     

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  7. 1MEGΩ

    1MEGΩ Active Member

    Messages:
    184
    Location:
    Mamou, Louisiana
    Do you have the service manual? You should do the Amp adjustments first. DC offset and Bias.
     
  8. nackesww

    nackesww Member

    Messages:
    96
    Location:
    New Auburn, Wisconsin
    AWM-062
    1..030
    2.-12.70
    3..025
    4.0
    5..024
    6..038
    7..030
    8..015
    9.36.48
    10.36.5
    11.36.51
    12..7.89AC
     
    Last edited: Apr 8, 2018
  9. nackesww

    nackesww Member

    Messages:
    96
    Location:
    New Auburn, Wisconsin
    I can do that. I briefly read through it . I'll look into it tomorrow. What do you think about the measurements I took? Do you still think Amp adjustments should be the next step?
     
  10. 1MEGΩ

    1MEGΩ Active Member

    Messages:
    184
    Location:
    Mamou, Louisiana
     
  11. 1MEGΩ

    1MEGΩ Active Member

    Messages:
    184
    Location:
    Mamou, Louisiana
    Once you get the Amp adjustments correct, and it still doesn't pull in the relay, we will troubleshoot the protection board.
     

     

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  12. nackesww

    nackesww Member

    Messages:
    96
    Location:
    New Auburn, Wisconsin
    I did the Bias today and I built a dim light tester as well. Sadly still no click of the relay yet.
    The new readings on the AWM-062 protection board is:
    1. 0
    2. -12.83
    3. 0
    4. 0
    5. -.01
    6. 0
    7. 0
    8. -.01
    9.36.69
    10.36.56
    11.36.56
    12. 7.91 AC
     
  13. nackesww

    nackesww Member

    Messages:
    96
    Location:
    New Auburn, Wisconsin
    Here are the transistor measurements
    BCE
    Q1 .008, 8.35, -.005
    Q2 .003, 8.37, -.017
    Q3 0, 36.50, -.806
    Q4 -.011, 7.94, -.630
    Q5 8.46, .625, 9.09
    Q6 .625, .004, 0
    Q7 .004, 36.66, 0
     
    Last edited: Apr 10, 2018
  14. 1MEGΩ

    1MEGΩ Active Member

    Messages:
    184
    Location:
    Mamou, Louisiana
    Something wrong with your transistor readings on the protection board. Q5 collector is directly connected to the base of Q6. You say Q5 collector is 9.09 volts and then you say Q6 base is .625 volts. That can't be,unless my schematic is wrong. Can you check the voltages again? Also, what is the voltage on the Anode of D8? Also, check R28. It should be 220 ohms. Another thing you need to do to make this easier is to check every transistor and diode with your ohm meter in diode test and see if any are shorted or open.
     
    Last edited: Apr 9, 2018
  15. nackesww

    nackesww Member

    Messages:
    96
    Location:
    New Auburn, Wisconsin
    I made a mistake. I listed my readings as BEC and should have listed as BCE. I went back and changed it.Sorry.
     
  16. nackesww

    nackesww Member

    Messages:
    96
    Location:
    New Auburn, Wisconsin
    I pulled and tested almost all of the components today and everything tested ok. I decided to look at the transistors to see if I installed them wrong. They were all installed right. And then I noticed Q3 and Q4 were not the same transistor as I saw on the schematics.I changed it out with the right one and the relay kicked in!!! :banana::banana::banana:

    I need to run some errands and when I get back I'm going to hook up the speakers and listen to some music. I still need to recap the power amp. I'll post updates.
     

     

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  17. nackesww

    nackesww Member

    Messages:
    96
    Location:
    New Auburn, Wisconsin
    The receiver is working again.sort of. I hooked the speakers up to speaker terminal A and got a 120hz humm/buzzing noise, you cant hear it with the radio turned up, but when you turn the volume all the way down is when its quite noticeable. I switched the speakers to speaker terminal B and the sound went away.
     
  18. 1MEGΩ

    1MEGΩ Active Member

    Messages:
    184
    Location:
    Mamou, Louisiana
    Glad it's working now. That's odd that it hums on A speaker terminals but not on B. The A and B terminals are both on the same circuit. Press A and B and see if it hums. Also make sure all chassis grounds have good connections to the chassis. It could be the main filters too. Make sure they have good solid grounds. Also, if you haven't cleaned all the controls and switches, now is a good time to do it.
     
  19. nackesww

    nackesww Member

    Messages:
    96
    Location:
    New Auburn, Wisconsin
    It turned out to be the volume pot ACV-164. After using Deoxit many times the buzzing has stopped.
     
  20. nackesww

    nackesww Member

    Messages:
    96
    Location:
    New Auburn, Wisconsin
    finished up on the power amp today and sounds great. I believe all I have left is replacing some lights. The lights that are burnt out is the speaker A and B, Aux, and 2-8v 0.3 amp bulbs.

    The only board I haven't worked on is the tuner board. I'm guessing nobody likes to mess with this board.
     

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