Recently acquired sx-1080 is a mess inside/ need a lot of help on this one

Discussion in 'Pioneer Audio' started by Jefferylu98, Sep 28, 2017.

  1. Jefferylu98

    Jefferylu98 AK Subscriber Subscriber

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    I have a little update. I replaced q6 and q7 on the right amp board and also a new set of resistors r/13-14. I can start it up and not smoking the resistors like before. Yaaaaaa. But now the speaker relay does not click like before. The soft start relay clicks. I did order a new q5 for the amp board?? Maybe that’s the cause. Center current reading will not adjust on the right amp board. Left is Fine and fully adjustable. I’ll keep plugging away on this basket case
     

     

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  2. slow_jazz

    slow_jazz Lunatic Member

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    Best of luck very good unit when working..
     
  3. Jefferylu98

    Jefferylu98 AK Subscriber Subscriber

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    Port Huron, Michigan
    Well I think I found the culprits on awh-071 right amp board. r-16/18 are reading are like 600 plus k ohm and r-17/19 are reading .6 ohms which I believe is in tolerance. Does anybody know of a replacement part number for these resistors?? I would like to replace all 4 while I have them out of circuit. I can't seem to find any info online or in any of these forums. pioneer part number RT5BOR5K. Thanks in advance for any help. I installed all new transistors, and tested all resistors/ diodes/zeniers with one leg out, and all were good except these two cement resistors.
     
  4. AUDIO1MAN

    AUDIO1MAN New Member

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    The output transistors NEC 2SB706 & 2SD746 are on Ebay
     
  5. Jefferylu98

    Jefferylu98 AK Subscriber Subscriber

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    I hope I don't need them
     
  6. petehall347

    petehall347 the brandy coffee man Subscriber

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  7. Jefferylu98

    Jefferylu98 AK Subscriber Subscriber

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    BTW: I did find a doner PA 1001 decoder chip, installed it and it plays stereo great now, I have it thru a Yamaha separate amp, until right amp issue resolved.
     
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  8. Jefferylu98

    Jefferylu98 AK Subscriber Subscriber

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    155
    Location:
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    Ok, I finally got time to pull the all 4 of the output transistors. I checked with DMM on diode setting and it don't look good (I believe) They are labeled BCE. RIGHT BACK = all pins solid beeps. RIGHT FRONT = all pins solid beeps. Left back = no beeps at all. Left front =C/ 0.483 AND E/ 0.518. I did replace the 4 resistors on the right amp board R-16/17/18/19. And checked all the voltages from the schematic and they seem to be correct on all pins. Center current set just fine but the idle current would not register or adjust on DMM. Do the amp boards have to be plugged in for the idle current to be adjusted??? I'm done with this till I get some advice as how to proceed on this basket case. BTW it all works great threw a separate amp, but I definitely want to try to fix it, correctly. Thank you guys for all your help and tips. image.jpg
     
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  9. petehall347

    petehall347 the brandy coffee man Subscriber

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    remove and retest transistors to be sure
     
  10. markthefixer

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

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    0.5 ohm 5 watt wirewound resistors RT5B 0R5K

    71-CP5J-0.5

    280-CR5-0.5-RC

    If it ate these, their output transistors are VERY suspect, use new... (didn't have time to analyze whole thread)
    Be sure the 22 ohm protect sensing/summing resistors are ok, one leg lifted because this is a "fool you" point...
     
  11. Jefferylu98

    Jefferylu98 AK Subscriber Subscriber

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    Thanks for the speedy reply MTF. I pulled r/23/24/25/26 out and they tested right on the money. I pulled all the transistors as directed from petehall347 (thank you also) and they are a mess. LOL. 5 out of the 8 failed with a diode test. OUCH. NOW WHAT?????? image.jpg
     

     

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  12. EngineerNate

    EngineerNate AK Subscriber Subscriber

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    Now you hope you can find replacements for them I'd think. The diode test is the most basic rest of a transistor, if they fail that they're totally toast.
     
  13. Jefferylu98

    Jefferylu98 AK Subscriber Subscriber

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    I think MTF has a workaround, but requires some mods. I'm up for the challenge. Ill just wait for my next instructions from the pros, and order some more goodies.
     
  14. rcs16

    rcs16 Super Member

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    Time to do some fabrication to fit in modern day packaged parts, ones in a TO-3P,TO-264 or MT-200 package.

    As said above search for what Mark came up with.

    reproduce the flange out of Al, so you can use the same mounting to the HS. mount new devices to the flange
     
  15. markthefixer

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

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    Do you have a dial (or electronic) caliper?

    calipers.JPG


    Need to know the exact distance between the holes,
    to see if the TO-247 cased replacements will fit in the rather unique envelope.
    It is slightly different than these:

    hold-downs-5.jpg

    And I think the transistors are larger and different from those used in the SA-8500ii and SA-9500ii
    We will have more flexibility in implementation than the picture below shows because the 1080's
    outputs are directly wired to a connector - no sockets involved.

    sa-8500-II_heatsink_view.jpg

    reference for myself later:
    SA-8500II 2SB617A 2SD587A
    SA-9500II 2SB618A 2SD588A
    SX-1080 2SB701A 2SD737A
     
    Last edited: Feb 10, 2018
  16. Jefferylu98

    Jefferylu98 AK Subscriber Subscriber

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    The hole centers are 24.3 mm. About. 61/64”
     

     

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  17. petehall347

    petehall347 the brandy coffee man Subscriber

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    mt 200 if you can find suitable in stock . for the ones above i would be tempted to use the old transistors as clamps like i have done in the past with no problems . not so pretty but works and can appear original looking through the vents .
     
  18. Jefferylu98

    Jefferylu98 AK Subscriber Subscriber

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    What about separating the old batwing off the transistor and use that as the new clamp??
     
  19. markthefixer

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

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    Sorry, the heat sink crowds the sides of the transistor?

    sa-7800_outputs..jpg

    sanken-mt200-case.jpg

    Fujitsu-RM60.jpg
     
    Last edited: Feb 10, 2018
  20. Jefferylu98

    Jefferylu98 AK Subscriber Subscriber

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    So if this is the style/case I’m working with, can I order the replacement transistors thru Mouser???
     

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