SA-9100 in protect

Discussion in 'Pioneer Audio' started by rcaman, May 18, 2018 at 1:15 AM.

  1. rcaman

    rcaman cornbread george

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    thanks for looking and i hope someone can help. the capacitors was toasted i replaced all of them with 105 degree caps. r13 390 ohm was crispy and r24 180 ohm was also crispy. now someone has worked on this before q1 has a 2sd526 and q2 has 2sb596 and the others don't match up either. q4 is 2sa673 q8 is 2sa673 q6 is 2sa673 q3 is 2sc1213 q5 is 2sc1213 q7 is 2sc1213. the voltage on pins 2 is -23v pin 3 -36v pin 5 is-61v pin 6 -62v pins 8,9,10,11 are ok. what do you guys think. the number on the power supply is awr-032-a
     

     

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  2. Beau Geste

    Beau Geste Addicted Member

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  3. UncleBingo

    UncleBingo AK Subscriber Subscriber

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  4. rcaman

    rcaman cornbread george

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    767
    Location:
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  5. UncleBingo

    UncleBingo AK Subscriber Subscriber

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    For my money the place it makes most sense to start is to measure DC voltage at the relay inputs. I'm not sure what the protection threshold V is, but if you have more than 250-300mv DC on the relay, the protection circuit may simply be dong its job.
     
  6. mbz

    mbz AK Subscriber Subscriber

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    I'm missing a schematic with transistor/part numbers so need to refer to attached pic, apologies.
    Seem like the transistor highlighted in yellow has failed short c-e, ie, no voltage regulation. This
    causes extra volts on pins 5,4,3,2. Pin 5 feeds the negative rail of the power amp, if this is out of spec
    it will cause a voltage inbalance with the positive rail ie, volts on speaker line and trigger protection.

    Suggest diode test the yellow highlighted transistor.

    upload_2018-5-19_20-17-20.png
     
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  7. rcaman

    rcaman cornbread george

    Messages:
    767
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    thanks i will check that today. that would be q2 2sb507
     
  8. rcaman

    rcaman cornbread george

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    767
    Location:
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    voltage checks on the protect board reviled pin 5 -35v pin 6 -29v pin 7 -81mv pin 8 -177mv pin 1 -40v pin 2 -130mv upon further inspection there has bee work on the left channel output board. q1 ,q2 ,q3 ,q4, and d2 have been replaced the transistors are ecg replacements. i have the correct transistors ordered. would this throw my power supply voltages off . the ouptut transistors are not shorted.
     
  9. mbz

    mbz AK Subscriber Subscriber

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    Post 1 has pin 5 at -61V which is what pin 6 should be as per schematic.
    Looking at only pins 5&6 voltages in post #8, these are unexpected, pin 6 should be greater than pin 5. Also, now there is a problem on Pin 8.
    If there is a short/large current draw, then maybe the power supply can't "stand up" but this looks different. I would wait on installing new transistors
    (unless they are cheap) until you get a better understanding of the problem. I assume these (pins 2,3,4,5,8,9,10,11) are wire wrap, ideally I'd like
    to disconnect the load but not if they are wire wrap, and see if the psu stands up.
     
  10. rcaman

    rcaman cornbread george

    Messages:
    767
    Location:
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    yes they are wire wrap and soldered.
     
  11. mbz

    mbz AK Subscriber Subscriber

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    Don't touch the wire wrap/pins.

    We have 2 sets of measurements for pins 5,6,7,8,,,
    with different results. Which are the rights ones? Post #1 or #8?
    Apologies but I need you to redo the dc voltage measurements again
    on the AWR-032/Power supply circuit board.

    Black meter probe connected to chassis/phono GND or black speaker post.
    - Pin 6, expect about -55->-62Vdc
    - Pin 5, -42Vdc
    - Pin 8, +42Vdc
    - Pin 7, +55->+62Vdc

    I will try and have a look at the transistor subs quoted in post #1
     

     

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  12. mbz

    mbz AK Subscriber Subscriber

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    I'm rather poor at transistor matching so happy if others disagree with following.
    The subs made appear ok. The case of 2SD526 and 2SB596 is live. Expect mica washer
    if heat sink mounted.

    q1 SM 2SD313P, has 2sd526
    q2 SM 2SB507P, has 2sb596
    q4 SM 2SA720, is 2sa673
    q8 SM 2SA720, is 2sa673
    q6 SM 2SA720, is 2sa673
    q3 SM 2SC945, is 2sc1213
    q5 SM 2SC1318, is 2sc1213
    q7 SM 2SC1318, is 2sc1213

    2SD313 (bce)
    2SD526 (bce) case is live
    Sub looks reasonable

    2SB507, complement to 2SD313
    2SB596, complement to 2SD526, case is live
    Sub looks reasonable

    2SA720 (ecb)
    2SA673 (ecb)
    Sub looks reasonable, 2SA720 is more robust. 2SA673A is preferred.

    2SC945 (ecb)
    2SC1213 (ecb)
    Sub looks reasonable

    2SC1213, complement to 2SA673
    2SC1318, complement to 2SA720
    sub ok, 2SC1213A is preferred.
     
  13. rcaman

    rcaman cornbread george

    Messages:
    767
    Location:
    mississippi
    thanks post #1 is the power supply readings with ground connected to pin 1 of power supply post #8 is voltage readings from the protect board with ground to pin 1 of power supply.
     
  14. mbz

    mbz AK Subscriber Subscriber

    Messages:
    1,761
    Location:
    Melbourne, Victoria
    Thanks for clearing that up. Looking at voltages on the protect board.

    pin 5 -35v
    pin 6 -29v
    Excessive dc voltage on left power amp, certainly trip protection

    pin 7 -81mv
    pin 8 -177mv
    Right power amp offset is high but insufficient to trip protection.

    pin 1 -40v
    Excessive dc voltage on left power amp. Pin 3 is for right channel.

    pin 2 -130mv
    Schematic has -13V, might be a problem with shorted zener D2 (WZ-130)
    on power supply board

    Possibly 2 problems.
    Power Supply (AWR-032)
    Remeasure voltages at pin 5(-42Vdc) to GND and then pin 6(-62Vdc) to GND
    Past measurement has Pin 5 at -61Vdc suggesting Q2 c-e short.
    D2 (WZ-130) may also have failed short.


    Power amp, Left
    Probably one of Q8,9,10,11 has failed. Voltage measurements to GND at
    pins 15,16,17,18,19,20 will probably help, maybe diode test Q10, 11, however
    it's more important to sort out any issue on the power supply board first.
     

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