Pioneer sx1010 troubles

Discussion in 'Pioneer Audio' started by Oscar23, Mar 25, 2017.

  1. Oscar23

    Oscar23 Member

    Messages:
    57
    Well I finally got to finishing up the amp board.powered it on and the d2 diode glowed bright red and smoke. I changed the diodes and all transitors on the board and it's still railed DC offset is reading 7v. Can't figure out why. Parts changed on board
    awh-032 Q1 2SA726 512-KSA992FBU
    awh-032 Q2 2SA726 512-KSA992FBU
    awh-032 Q3 2SA726 512-KSA992FBU
    awh-032 q4 2sb528 ksa1220 / ksa1381
    awh-032 Q5 2SC1451 512-KSC3503DSTU / KSC2690?
    awh-032 Q6 2SC1451 512-KSC3503DSTU
    awh-032 q7 2sd358 ksc2690
    awh-032 q8 2sb528 ksa1220
    awh-032 q9 2sc1448 ksc2073
    awh-032 q10 2sa740 ksa940
    awh-032 q11 2sc945 512-KSC1845FTA
    awh-032 q12 2sa733 512-KSA992FBU
    awh-032D2 1S2473 512-IN4148
    awh-032 D7 1S1885 512-UF4004
    awh-032 D8 1S1885 512-UF4004

    awh-032 VR1 2.2K multi T 652-3296P-1-202LF
    awh-032 VR2 470 ohms 1T 652-3386H-1-501LF
     
  2. zebulon1

    zebulon1 Into Phase Linear's lately Subscriber

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    It's a pain at first but your going to have to check all the resistors for value.
    Are you using the DBT?
     
  3. Oscar23

    Oscar23 Member

    Messages:
    57
    Yes I am 100 watt bulb should I get I bigger one
     
  4. LWB

    LWB AK Subscriber Subscriber

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    Location:
    Calgary, Alberta, Canada
    100 watt bulb is fine. Somewhere, you have a nasty short. Believe me, I feel for you! Check every trace, every component on the amp board. Do yourself a favour and always power up after new work ONLY through the DBT.

    Bright to begin,
    and when the light dims,
    it's ok to start,
    be still my poor heart.
     
  5. Oscar23

    Oscar23 Member

    Messages:
    57
    I got.r34,r35,r21 were all out of spec when I tested them in circuit all tested ok but when I went I pulled them out r34,r35 were reading 11 ohms. zip it back up and it's singing proudly. Lesson learned this is not a beginner reciever wires break not easy and when they say change the 2sc1451 do it it's going to fail and when it does it will take other things out with it. It was the first thing to go when I started and I ended up replacing half the amp board. The second thing once you get this just running the sx1010 will fight back I would get one thing fixed and something else would fail. Just rebuild it.
     
  6. LWB

    LWB AK Subscriber Subscriber

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    Calgary, Alberta, Canada
    Congratulations on finding the culprits!
     
  7. Oscar23

    Oscar23 Member

    Messages:
    57
    No I was wrong it comes out of protection now but getting 0 on the bias won't go up or down
     
  8. zebulon1

    zebulon1 Into Phase Linear's lately Subscriber

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    Explaine:
    DC Balance? Or Offset Should be 0 (Zero) mV's
    Or Idles? Should be 25mV's
     
  9. Oscar23

    Oscar23 Member

    Messages:
    57
    DC balance is at 6mv won't go to 0 the bias is at 0 but it comes out of protection
     
  10. Oscar23

    Oscar23 Member

    Messages:
    57
    I can't get the bias to go higher to 0 its like there is none I'm measuring it at 14 and 16
     
  11. zebulon1

    zebulon1 Into Phase Linear's lately Subscriber

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    Can you adjust the other amp?
    Check all the wires connecting to the amp board. Tug on them making sure that they are connected.
    Check the voltages at pins 8, 11, 12, 3, 7, 4. All are DC volts.
     
  12. Oscar23

    Oscar23 Member

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    57
  13. zebulon1

    zebulon1 Into Phase Linear's lately Subscriber

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    I posted some more info above.
    You messed up something. It's probably not serious. Double check all the transistor placements making sure they are installed correctly and I hate to say this, but there might be a solder joint that got missed. Did you install the new Bourns trimmers?
    If so check and make sure they are not swapped.
     
    Oscar23 likes this.
  14. Oscar23

    Oscar23 Member

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    I will in the morning....lol in there again those wires have broken so many times would there be a good way to make them a little longer. I have some bare copper I thought about fusing to the ends to rewrap them
     
  15. zebulon1

    zebulon1 Into Phase Linear's lately Subscriber

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    Not much you can do with out 22 gauge hook-up wire and a special tool.
    Once you solder to the wrapping posts, it's a done deal. Soldering compromises the sharp corners and renders the post useless for rewrapping.
     
    Last edited: Apr 29, 2017
  16. Oscar23

    Oscar23 Member

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    I've been soldering them to the old wire
     
  17. Oscar23

    Oscar23 Member

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    57
    I checked those points
    8 41.7
    11 41.8
    12 41.8
    3 -54.7
    4 54.4
     
  18. zebulon1

    zebulon1 Into Phase Linear's lately Subscriber

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    Those are good.
    Trouble is in the board (Somewhere)
    You'll have to check it over again.
     
  19. Oscar23

    Oscar23 Member

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    57
    I got the offset to go down what's the highest I can have it
     
  20. zebulon1

    zebulon1 Into Phase Linear's lately Subscriber

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    If its stable. 20mV's or so.
     

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