SA-9100 Protection light on and off

Discussion in 'Pioneer Audio' started by Toren, Oct 27, 2017.

  1. Toren

    Toren New Member

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    23
    I have a SA-9100 that recently goes into protection after about 5 minutes. The light will turn on for about 2 seconds, I'll hear the relay, light turns off for about half a second, and then turns back on again. What's more weird is that I'll turn it off for a couple minutes and when I turn it back on the same thing happens but in longer time intervals 3-4 seconds on, 1 second off. Then the light will stay off another 5 minutes or so, rinse and repeat. Help!
     
  2. zebulon1

    zebulon1 Cleaned up the shop and half finished sets. Subscriber

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    Check the amp settings:
    DC Balance (Neutral)
    Idles.
    Best to check the readings at this point. Any adjustments, if unsure, can cause more issues.
    You don't need the load resistors. Make sure the volume is dialed to minimum.

    sa-9100 amp setting.PNG
     
  3. markthefixer

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

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    Shorter than time delay intervals of protect going out and in means the relay coil drive transistor is flakey, NOT the protection circuit or it's inputs.

    Download or buy (stereomanuals.com suggested) a service manual. The protect board is AWM-025 and can be found in the BOTTOM of the chassis, mounted on plastic pins that can be squeezed to release the board for component soldering access.

    Get a 512-KSC2690AYS into the Q7 position on the AWM-025 board.
    also get a 621-1N4004 diode and install it between pins 9 and 10 of the AWM-025 board, with the banded end of the diode connected to the pin 10 side

    The original transistor is a 2sc1384 with an ECB layout
    while the KSC2690 datasheet reveals an ECB layout.

    The 2690 leads and body are a little larger (for longer life!!) and the leads are a tight fit in the holes, but they DO fit, flux residue in the hole may make it a tight fit, but a little heat will overcome that. So will poking through other wires through the hole to clear it.
     
    Last edited: Oct 30, 2017
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  4. inductor

    inductor Super Member

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    really need to see if its dc at the amps o\p causing it or the protection cct itself, lots of problems on the protect board recently, too many to go into unless mark is on song
     
  5. Toren

    Toren New Member

    Messages:
    23
    I'll order transistor and diodes tomorrow. How do I check if there's dc at amps output? When adjusting idle current, what does the manual mean by output load and installing 4.7k ohm resistor on input terminal 3 to what? I wish I got emails when I get posts on this thread, would've responded quicker. I'll check post more often. Are accurate readings possible if amp keeps coming in and out of protection mode?
     
  6. zebulon1

    zebulon1 Cleaned up the shop and half finished sets. Subscriber

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    As long as you take the readings where the service manual states. Follow the manual.
    You can get by without the resistor. Make sure you have the volume at min.
    Complete the D.C. Balance and idle check/procedure as the first step and see where that leads.
     
  7. Toren

    Toren New Member

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    23
    Markthefixer do you have an updated list of transistors for Q1-7 on the protection circuit? I keep looking for a recent list but seems like most parts are obsolete.
     
  8. markthefixer

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

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    what are your intentions - a shotgunning of the circuit - especially without any voltage readings?

    I told you true, the circuit pulling in (or trying to) means it is working up to the relay driver transistor.

    here is a parts list - the awm-025 IS used in a LOT of models!!!

    http://audiokarma.org/forums/index.php?threads/sx-838-protection-board-rebuild.592503/#post-7804056

    read the WHOLE thread.

    You will find the KSC1845 transistors to be temporarily out of stock, all over...
    Replacing C1 and C2 is the third highest priority after the relay driver transistor and the flyback diode installation. They are the troublesome sky blue sanyo capacitor/resistors. Their failure might not be noticed until an over current shutdown to the speakers DOESN'T happen. Then the smoke really gets out.
     
  9. Toren

    Toren New Member

    Messages:
    23
    Not trying to shot gun, just figured I'd replace caps and transistors once protection issue was fixed. Will take voltage reading tonight and post
     
  10. Toren

    Toren New Member

    Messages:
    23
    Okay warmed the amp up and now it won't come out of protection mode.
    Checked idle current
    Right channel terminal 9 to 13 22-33mV, seems like adjusting vr 1 and vr 3 doesn't do much.
    Left channel terminal 9 to 13 0v, nothing happens when adjusting vr 1 and vr 3.

    What other voltages do you want me to check?

    Mind that both channels were playing when i used to be out of protection mode
     
    Last edited: Nov 6, 2017
  11. Toren

    Toren New Member

    Messages:
    23
    Okay so I went did some readings.

    AWM-025-C board:
    1) 171mV
    2) -2.11V
    3) 253mV
    4) 0V
    5) 172mV
    6) 172mV
    7) 261mV
    8) 244mV
    9) 35.5V
    10) 35.5V
    11) 35.5V
    12) 6.8Vac

    AWH023 RIGHT:
    1) 25.2V
    2) 0V
    3) 0V
    4) 0V
    5) 5.8mV
    6) -3.98V
    7) 0V
    8) 43V
    9) 260mV
    10) 0V
    11) -44.9V
    12) 254mV
    13) 245mV
    14) 45Vdc/98.6Vac using a cheap meter until I get my Fluke 87 so I don't know if ac is supposed to be present


    AWH023 LEFT:
    1) 25.9V
    2) 0V
    3) 0V
    4) 0V
    5) 6mV
    6) -3.78V
    7) 0V
    8) 43v
    9) 173.1mV
    10) 0v
    11) -45.1V
    12) 0V
    13) 173mV
    14) 45Vdc/98.1Vac using a cheap meter until I get my Fluke 87 so I don't know if ac is supposed to be present
     
    Last edited: Nov 7, 2017
  12. zebulon1

    zebulon1 Cleaned up the shop and half finished sets. Subscriber

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    Model 87? Nice. I use mine at work. Great Meter.
    It looks like the right amp's DC balance is off by 200mv's or so. It should be reading 0v's (zero) like the left seems to be.
    Double check these readings before moving forward.
    Pin 6 in the amp boards (AWH023) should be reading -42v's.
    Pin 9 should be +42v.
     
  13. Toren

    Toren New Member

    Messages:
    23
    markthefixer,

    How should I proceed? I think I missed pin 7 on left, will verify when I get home.
     
  14. Toren

    Toren New Member

    Messages:
    23
    I was driving myself crazy trying to figure out why the protection board wasn't matching foil layout or schematic. The protection board is AWM-025-C not the A version. I found a foil layout from an AWM-062 that matches but no schematic. Will attach foil layout. Seems to use same transistors but uses 2SC869 instead of 2SC857K. Any good replacements for the 2SC869's and main power caps (they look tampered with)? I fixed my voltage readings too. Any help would be greatly appreciated!
     

    Attached Files:

  15. markthefixer

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

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    15,000 uf 50v caps? Need measurements of diameter and height.

    2sc869 gets replaced by ksc1845.

    sorry about the delay, I just looked in.

    awm-025 board pin 2 should be at -13v for proper operation , not -2v.

    I am going to utilize your excellent skills in taking readings, power supply circuit b assembly AWR-032, pins 1 through 11 inclusive.
    That will spot the -13v problems.

    Then go to power supply circuit a assembly AWR-031 and read pins 5 & 8 in AC, pins 6 & 7 in DC, pin 9 is supposed to be grounded.
    The awr-031 board has two fuses, with power off, pull the fuses and check for sub 5 ohms.
     
  16. Toren

    Toren New Member

    Messages:
    23
    AWR-032
    1) 0V
    2) 898mV
    3) 430mV
    4) -1.74V
    5) -3.22V
    6) -60.1V
    7) 59.2V
    8) 43.4V
    9) 36V
    10) 25.6V
    11) 17V

    AWR-031
    5) 43.6Vac
    6) 58.8Vdc
    7) -59.5Vdc
    8) 43.6Vac
    9) 0V

    The 2 fuses on the AWR-031 board measured 2ohms on the crap DMM so probably shorted as expected. R4 looked crispy but read 817ohm out of circuit, will replace anyway.
     
    Last edited: Nov 9, 2017
  17. markthefixer

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

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    Ah ha. (GREAT job on the readings, I was able to jump right in!!)

    the awr-031 board is performing correctly. Feeding the raw voltages to the awr-032 regulators.

    AWR-032
    1) 0V this is ok
    2) 898mV bad, should be -16v but can be ok if -42v is fixed AND the -24v is working.
    3) 430mV bad, should be -24v but can be ok if -42v is fixed
    4) -1.74V bad, should be -13v but can be ok if -42v is fixed
    5) -3.22V bad, should be -42v here is the start of the problem,

    but this problem masks whether the rest of the negative regulators are working
    (pin 4 = -13v, pin 5 = -42v, pin 3 =-24v, pin 2 = -16v)

    6) -60.1V this is ok, the negative regulators are being fed properly
    7) 59.2V this is ok, the positive regulators are being fed properly
    8) 43.4V this is ok
    9) 36V this is ok
    10) 25.6V this is ok
    11) 17V this is ok

    Thus Q2 2sb507 and Q4 2sa720 are suspect and one or both is falling down on the job.
    Q2 "makes" the master -42v, that feeds the -13, -24 and -16v regulators.
    So the other regulators can't be checked until the -42v is present again.


    We can go a step further and read / post the three each (e,c,b) Q2 and Q4 voltages, or replace just q2 and q4.

    R4 is part of a low current power feed to operate the regulator. IF it looks crispy the regulator failure took it out and it should be replaced.

    HERE'S the catch: WHY is the -42v busted? did a problem with one of the OTHER voltages take it out with an overload? pins 2 and 3 with POSITIVE millivolts makes me a wee bit suspicious.

    we could fix it, only to have it fail again. just preparing you...


    This is for educational purposes for the "gallery".
    R2 / C2 form a ripple rejection filter, to power the regulator with CLEAN dc - ANY AC will go right through the regulator - that's why the JFET constant current source (and the EchoWars constant current source for the higher voltage on the SX-1980) is used, instead of relying on brute force filtering with a HONKING BIG CAP to get the hum out like this typical Pioneer regulator does, the circuits supplying the constant current reject the hum. In another high end Pioneer amp (class a power amp?) I saw a full blown current source circuit implemented with a transistor and resistors.
     
    Last edited: Nov 9, 2017
  18. rcs16

    rcs16 Super Member

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    Sansui did this also on the AU-X1
     
  19. Toren

    Toren New Member

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    23
    Anything I can do to avoid a failure after replacing q2 and q4? I will give ecb readings of transistors when I get home from work.
     
  20. markthefixer

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

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    not really. it's a low probability event

    parts:
    upload_2017-11-9_21-18-41.png
     

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