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Pioneer sx1010 troubles

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

  1. markthefixer

    markthefixer On Hiatus, dealing with Dad's estate full time Subscriber

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    OK, this is gonna take a bit of work - because the amps are untrustworthy and probably in need of troubleshooting - or at least proving that they are ok. We HAVE to go about this systematically - sorry - but this is how I would do it on my bench - even if pressed for time. There is a thread somewhere in here where this was done, and if anyone remembers removing outputs and restoring DC balance to the sx-1010 power amps by adding resistors in place of the output transistors, PLEASE chime in. I am limping along on an old laptop - the AK Dell Inspiron N5110 Win 7 laptop from 2012 has a probable hard drive failure that I cannot work on until I can get parts etc after the holidays. This is the Dell Latitude D610 Win XP laptop that lost the hard drive in 2012, which I eventually repaired.

    Step 1: REMOVE the output transistors, insulate the empty hanging sockets so nothing will short. RECORD EXACTLY WHICH TRANSISTOR CAME FROM WHICH SOCKET!!! Not just the "flavor" pnp/npn, but each individual!!

    Then try the power again, and see if the bulb goes dim. If it dims, take power supply readings, concentrating upon the major regulated outputs of pin 14 (+56), pin 10 (-56) and pin 8 (+13v) and if they are within 10% of those values, they are ok and we can move on to the amps - DON'T sweat it if the protection relay does NOT click.
     

     

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  2. Oscar23

    Oscar23 Active Member

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    Ok and I remember reading that post I'll look for it again hopefully it's still around and not pressed for time I've been. In and out of this thing for almost a year now. Using the lessons learned to fix other things I'll work step by step with you and won't go any further till told so.
     
  3. Oscar23

    Oscar23 Active Member

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  4. Oscar23

    Oscar23 Active Member

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    I pulled the outputs out and the bulb went dim and here is the reading for those three pins. Pin 10 is perfect but pin 4 is wrong at least we know where to start I really appreciate your guidance
    Pin 14 11.6
    Pin 10-57
    Pin 8-6.4
     
  5. markthefixer

    markthefixer On Hiatus, dealing with Dad's estate full time Subscriber

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    No.

    With the outputs removed, the feedback system has no input. The procedure adds two resistors, probably between the base drives for the outputs and the output terminal BEFORE the zobel filters. Gotta get the values (resistance and wattage) correct, and recalculating is a headache and effort that I hope to avoid.
     
  6. Oscar23

    Oscar23 Active Member

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    Ok then I'll keep looking but the voltage on pin 10 did go correct when the outputs are out so is it safe to say there is something wrong with the outputs?
     

     

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  7. Oscar23

    Oscar23 Active Member

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  8. Oscar23

    Oscar23 Active Member

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  9. markthefixer

    markthefixer On Hiatus, dealing with Dad's estate full time Subscriber

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    Well, knowing it was the craxx6969 thread helped find the actual meat of the procedure quickly.

    Ok, here is a modified version of the post that started it all. I left the link to the original in, for referencing back to that thread.

    This is for illumination and understanding, it is NOT YET TIME TO HEAT UP A SOLDERING IRON!!!

    It would be better if pin 19 was not used and rather the connections made to another point before the zobel filters (inductor etc).
    There is a large foil on the pc board where all four large white resistors and the output inductor filter are all connected together.
    THAT would be the best common point for the two test resistors.
    Perhaps a pad of a lead of the large white resistors can have a wire tacked onto it. And fly the insulated lead over to near pins 10 and 13.
    Pins 10 and 13 are each MOUNTED by a convenient solder pad, just WAITING for a resistor lead to be tacked on.

    dc balance without outputs.JPG
     
  10. Oscar23

    Oscar23 Active Member

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    Ok so what do I need to order or see if I have
     
  11. markthefixer

    markthefixer On Hiatus, dealing with Dad's estate full time Subscriber

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    Well, I can tell you did NOT read the quote carefully:

    Do you have some ~ 250 ohm to 2k ohm, 5+ watt resistors laying around? These would survive fault conditions.

    Otherwise some 20 to 50 ohm resistors, say 1/4 to 1/2 watt. IF there is a fault, these would blow up spectacularly.
    There only should be about a 1.2 volt difference between pins 10 and 13.

    5 watt resistors. two of the same value in the range of 250 to 2000 ohms

    a pair of 1000 ohm 5 watt resistors. mouser 71-CP00051K000JE14 would do nicely and are the least expensive.
     

     

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  12. Oscar23

    Oscar23 Active Member

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    Ok for some reason I didn't see the yellow part I do know. I have tons of 20 to 50 ohm resistor around but would I be better off waiting till the right ones came in I have an order going out in the next week. We could try the 20 ohm if they blow then just wait till the others come in. What do you think would be best
     
  13. Oscar23

    Oscar23 Active Member

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    I have the resitors waiting for ok to proceed
     
  14. Oscar23

    Oscar23 Active Member

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    I lifted one leg on every resitor all test good. Ready to move forward when you are
     
  15. LWB

    LWB AK Subscriber Subscriber

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    If I'm not mistaken, the procedure to follow with the resistor substitutions is described in post 149.

    :lurk:
     
  16. Oscar23

    Oscar23 Active Member

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    Yes but he also told me it was posted to explain to me what he wants to do but not to turn my soldering iron on
     

     

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  17. Oscar23

    Oscar23 Active Member

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    OK I don't know if this is the best way to proceed but here's my plan I'm going to get the power supply voltages right then proceed to test the amp using the method above. I'm not sure if this is the best way but makes sense to me..any opinions?
     
  18. Oscar23

    Oscar23 Active Member

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    OK update I reread through the posts and my question has been answered I do not have the power supply up to 10 % so I'm not ready to move on which would explain why I've been left in the air.... I really need to slow down when reading
     
  19. SaturationPt

    SaturationPt Fickle Collector Subscriber

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    Yes, power supply voltages is IMO always the first step. If restoring, I restore the power supply first, ... if diagnosing I verify/repair power supply and voltages first. Without proper power it cannot be expected to work correctly and diagnosis is difficult.
     
  20. Oscar23

    Oscar23 Active Member

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    Unfortunately this is what I'm working with this unit was worked on before I got it and has been a mess. I know pin 10 is fine a little high actually.pin 14 is about 1/2 of what it should be so I know witch transitor to look at judging by that mess bad trace or solder joint and I'm pretty sure where about. If I understand correctly pin 8 is the feed back system so I get that other voltage up it should follow suit.
     

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    Last edited: Feb 1, 2018

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