Pioneer SX-950 wont come out of protection

Discussion in 'Pioneer Audio' started by CavScout, Jul 2, 2018.

  1. CavScout

    CavScout Active Member

    Messages:
    474
    Hi folks

    I am hoping some of the experts out there can assist me with a problem I am having.

    I just bought an SX-950 and the unit will not come out of protection at all.

    I hooked up a DBT and there are no shorts.

    I would like to start with the simple stuff so.......
    Is it possible if I remove it and deox it that it will work or ???

    Any assistance is greatly appreciated

    Thanks
     

     

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  2. petehall347

    petehall347 the brandy coffee man Subscriber

    Messages:
    26,232
    Location:
    uk.. the middle bit
    check voltages at the protect circuits pins .
     
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  3. CavScout

    CavScout Active Member

    Messages:
    474
    I have a basic Fluke multimeter. What do I set it to?
    Do I put the black to the stereo frame as ground?
    What readings am I looking for?
    Thanks for your help
     
  4. slimecity

    slimecity Super Member

    Messages:
    2,589
    Location:
    New Zealand
    You will need to find & download the service manual for this model.

    Set the meter to DC mV.

    You will need to measure the DC mV (very carefully) at the points petehall refers to - these will measure the DC offset at the amount going into the speaker protect relay side.
     
  5. w1jim

    w1jim I can fix it but good... Subscriber

    Messages:
    7,520
    Location:
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    Go to hifiengine.com and download the service manual.
    Read it, check the dc offset and bias as described therein.
     
  6. 1MEGΩ

    1MEGΩ Active Member

    Messages:
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    Location:
    Mamou, Louisiana

     

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  7. 1MEGΩ

    1MEGΩ Active Member

    Messages:
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    Location:
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    Power Amplifier voltages on Page 76, Protection Circuit voltages on page 81, not numbered, and Power Supply voltages on page 84, not numbered. Just scroll down the pages to find them.
     
  8. CavScout

    CavScout Active Member

    Messages:
    474
    Thanks folks.
    I am not very good at reading elec schematics at all.
    But I do see 8 voltages referred to on that page .

    There are 4 pins that are bridged and 2 that are single.

    The voltages that I see on that page are
    36.5

    1.0
    7.5
    13.5
    5.1
    0.6
    0.6
    0.7

    So there are references to 8 voltages but 10 pins (including the bridges.......and I would assume each bridge would have equal voltage reading)

    Also, silly question guys but... I hold the red to the test point and clip the black to the frame of the unit right ?
     

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  9. CavScout

    CavScout Active Member

    Messages:
    474
    Should the unit be on or off while taking these readings?
     
  10. w1jim

    w1jim I can fix it but good... Subscriber

    Messages:
    7,520
    Location:
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    That's an easy one - ON.
    But be careful not to short out any pins while taking measurements.
    Your ground lead goes to the chassis.
     
  11. CavScout

    CavScout Active Member

    Messages:
    474
    So when I tested it with the unit off the readings were falling fast until zero.
    I guess this is because the caps behind these readings are dumping to the frame?
     

     

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  12. CavScout

    CavScout Active Member

    Messages:
    474
    The Mv AC readings that I got were

    From the 2 orange wire connections
    67.5
    377.0 ( very erratic)

    From the 2 yellow wire connections
    71.2
    97.1

    From the grey wire (to a single pin)
    10.3

    From the black/white wire (to a single pin)
    0.5
     
  13. Markoneswift

    Markoneswift Quartz locked n ready to rock

    Messages:
    3,058
    Location:
    Aotearoa New Zealand
    Yeah you need the unit on for testing voltage and usually off for resistance etc
     
  14. Markoneswift

    Markoneswift Quartz locked n ready to rock

    Messages:
    3,058
    Location:
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    Hopefully those were mV DC :)
     
  15. Markoneswift

    Markoneswift Quartz locked n ready to rock

    Messages:
    3,058
    Location:
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    And I'm thinking you've got a whole lot of DC hitting that protection circuit.
     
  16. Markoneswift

    Markoneswift Quartz locked n ready to rock

    Messages:
    3,058
    Location:
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    I might have one of these to work on myself soon so .....:lurk:
     

     

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  17. CavScout

    CavScout Active Member

    Messages:
    474
    I followed the previous Instructions in this thread and set it to MV which was AC.

    So for DC, i set it to V and the readings were

    15.94
    15.11
    .005
    .005
    1.21
    1.21
     
  18. CavScout

    CavScout Active Member

    Messages:
    474
    Here is where I have it set now
     

    Attached Files:

  19. Watthour

    Watthour Electron Rancher - JS3600

    The wire wrap connection pins have numbers assigned to them. It would help to know what voltages are a which pins, since colors are not always consistent. For example, Pins 1 should normally be at or below 0.010VD, Pin 2 should be around 13V (-), Pin 3 should be at or below 0.010VDC, etc.
     
  20. CavScout

    CavScout Active Member

    Messages:
    474
    Watthour those are not far from what I measured

    15.94
    15.11
    .005
    .005
     

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