Pioneer sx1010 troubles

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

  1. Oscar23

    Oscar23 AK Subscriber Subscriber

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    I acquired a pioneer sx1010 it had no sound on left side. I put it on the dim build tester and bright turned it off removed b539 light went dim and one I tested replaced them with mg21193 plugged it back in with the dbt bulb went bright again.
    This machine was worked on before power supply was rebuilt, and I changed all 2sc1415 and 2sc726. Can't figure out what else to check.
     
  2. zebulon1

    zebulon1 Into Phase Linear's lately Subscriber

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    Pull all the fuses on the fuse board AWR-063.
    Recheck the set using the DBT.
    If the bulb remains bright you'll have to revisit the amp boards and outputs.
    Let's see what happens before tearing it apart.

    Note:
    Before reinstalling the fuses make sure they all have the correct values. Good practice.
    Not that it matters now but you should install the matching output. The modern MJ's are a lot different than the old NEC's. It might be ok to use it for troubleshooting but not as a permanent fix.
     
    Last edited: Mar 26, 2017
  3. Oscar23

    Oscar23 AK Subscriber Subscriber

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    Ok took all the fuses out and bulb still bright
     
  4. zebulon1

    zebulon1 Into Phase Linear's lately Subscriber

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    Did you do anything else to the set? Like replace the big filters?
    If No:
    You still have a short in the amp circuit. Outputs and or the amp board.
    Whenever an output is toast the amp board circuit has been compromised.
    The easiest way is to check each output and find the shorted one(s). A little bit of a crap shoot. You'll have to loosen up both amp boards buy removing the black metal supports along with the heat sinks. (You've been there)
    I put a towel across the top of the set and rest the assemblies on it leaving the harnesses connected.
    Remove one output at a time and check it thoroughly replace and move to the next.
    Once you find it, then its colleagues should be replaced with the On-Semi's and the amp board checked completely.
    All the transistors, diodes and resistors for condition and values.
    The forum has a wonderful list by MTF for the diodes and transistor equivalents.
    There are no short cuts in this repair. The 1010 will fight back hard without a thorough check. The time spent on an organized approach is time well spent.
    No hurries!
     
    Last edited: Mar 26, 2017
  5. Oscar23

    Oscar23 AK Subscriber Subscriber

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    Ok I haven't changed nothing else I was waiting till this part was done could my new ones be toast to I haven't taken it off the dim bulb tester
     
  6. Oscar23

    Oscar23 AK Subscriber Subscriber

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    I checked all transistors, resistors, and diodes and good news rechecked my original output transistors and they tested fine ( there was a short on one of my test leads grrrrrrrrrrrrrrrrrrrrrrrrrrrrrr) but the 2sa740 was cooked I looked further down on the circuit and the trace was burnt right through. There was one diode burnt 1s1885 (d8) witch was on the trace that was burnt. The end of my stv3h broke off to I have a replacement now here's my question which way does it go in I see there is a dot on one side I have the awh o32-d version of the board
     
  7. zebulon1

    zebulon1 Into Phase Linear's lately Subscriber

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    The markings on diodes usually indicates the cathode.
    Can you compare to the other amp to verify?
    The 1010 amp board has several STV diodes depending on the mod status.
    Nice work.
     
  8. Oscar23

    Oscar23 AK Subscriber Subscriber

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    Ok I think I got it figured out the d8 on my board is a stv3 not a 1s1885 are these interchangble in this spot and r22 was not there by factory for some reason neither board has one
     
  9. Oscar23

    Oscar23 AK Subscriber Subscriber

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    Here is where the break is as I've said someone has worked on this board before it goes right from the 2sa740 to the stv3 (d8) I'm just going to bridge it with a wire rather than try to patch that mess
     

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  10. zebulon1

    zebulon1 Into Phase Linear's lately Subscriber

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    Sounds like a good plan.
    I'll use cutoffs from the bigger caps for bridges.
    That's a pretty good span to make.
     
  11. Oscar23

    Oscar23 AK Subscriber Subscriber

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    After waiting for my parts from mouser I've fixed the broken trace and a few other bad solder joints change the 2sa740 and matched up the outputs and there counter parts. In the process had a few wires break off does anyone have a photo of the top pins on the amp boards so I can insure that they are in correct I would match it up with left board but wire colours are different
     
  12. zebulon1

    zebulon1 Into Phase Linear's lately Subscriber

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    You should check per the scat to make sure the other end terminates at the correct board or socket.
    Never assume. Others may have been in there messing about.
    Take your time and double check your work.

    [​IMG]


    [​IMG]
     
  13. Oscar23

    Oscar23 AK Subscriber Subscriber

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    Yes for sure maybe a better route my board is different than that one and the wire colours are different
     
  14. zebulon1

    zebulon1 Into Phase Linear's lately Subscriber

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    Some tips:
    The finer 20 gauge wires that go to the output sockets are the Base connections.
    One of the pins are for the protection board.
    Others are for the signal and signal ground.
    Several of the larger 18 gauge are considered the same and even if they are connected to two different pins they are of one. (Both pins share the same trace)
     
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  15. Oscar23

    Oscar23 AK Subscriber Subscriber

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    Here's what I did I matched where they started on the scemantic then put my dmm in continue on the pin then matched it up on the other side to make sure it was right from pin to pin
     
  16. Oscar23

    Oscar23 AK Subscriber Subscriber

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    The two empty ones are for the stv3 diode
     

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  17. LWB

    LWB AK Subscriber Subscriber

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    I just re-did my own 1010 and I found that repeated working on the pcb's strained the wrapping posts' solder joints, and also, it is easy to break a wrapped joint by pulling on the board to get it clear to work on, and then not notice that a wire is disconnected, perhaps even shorted. My DBT indicated a short, and I pulled my hair out re-checking all of my work, finding no problems. I re-flowed the wrapping posts' solder joints around the periphery of the power supply board (this board had been in-and-out a lot, I had broken a wrapped wire there, too) and that solved the problem. I don't know which post was the culprit, but in re-flowing them all I fixed it. Another problem area I found was the control amp, it is a tight squeeze to pull it out to work on it. If you've worked on it, check the wire-wraps there, too.
     
  18. Oscar23

    Oscar23 AK Subscriber Subscriber

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    The wires in this thing is a nightmare I've found a few that have broken haven't even got to the control board
     
  19. LWB

    LWB AK Subscriber Subscriber

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    If you haven't done so, I would recommend that you cut a piece of 5/8" or 3/4" plywood and countersink holes at the same spacing as the walnut case, and fasten this rough plywood side panel to the chassis. Then you can stand the 1010 on its side and have access to both sides. Make a lazy susan turntable, too, so you can spin it around. Whatever board you're working on, you can access the wiring on the backside; slip it out of the nylon looms to loosen it so that you have a bit more leeway to pull whatever board you're working on away from the chassis. This is much gentler on the wiring.

    Bench_IMG_0205.jpg
     
    Last edited: Apr 3, 2017
  20. Oscar23

    Oscar23 AK Subscriber Subscriber

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    You know that is a great idea I'm going to make one it would be handy on a lot of units these big ones are very cumbersome to work on
     

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