SX-980 Protection Overload Condition

Discussion in 'Pioneer Audio' started by danyost, Dec 23, 2014.

  1. zebulon1

    zebulon1 Getting behind on work. I need help? Subscriber

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    If MTF were to say anything, he might say this: :scratch2:

     

     

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  2. danyost

    danyost New Member

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    I'm going to be enjoying the best sounding receiver I've ever owned for as long as I can keep it running!
    I've also got a CTF-1000 I'm going to fix the belts on. I do have some original recordings on cassette that I'd like to hear again providing that the tapes hold up. She's a beauty!
     
  3. markthefixer

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

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    Spot on Zeb... :D

    I have LOTS of stuff waiting in the wings to sing again...
    (one of them too)
     
  4. danyost

    danyost New Member

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    Awr-156

    To clarify... AWR-156?
     
  5. danyost

    danyost New Member

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    BTW... thanks for the great support Mark; I couldn't do it without you. And Zebulon1, thanks so much for stepping in and making it so easy to get the parts ordered!
     
  6. zebulon1

    zebulon1 Getting behind on work. I need help? Subscriber

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    AWR-156 is the Power Supply board on a sx-980. We use the designation to clarify when discussing a particular board on a set (mostly when posting a component list).
     

     

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  7. markthefixer

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

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    That's an older post, it didn't specifically SAY awr-156 and when it gets QUOTED out of an old thread that provides the context it gets confusing.

    So:

    Replace
    awr-156 Q3 2sa850
    also because of potential overstress:
    awr-156 q4 2sb682
    awr-156 d9 mz-130

    although considering the effort, a full rebuild of the board will not add much expense or effort, with an increase in reliability.

    awr-156 q1 2sd712 100v 4a 30w 55-300hfe 8mhz
    512-KSC2073TU npn to-220 bce 150v 1.5a 25w 4mhz 40-140hfe $0.54
    awr-156 q4 2sb682 100v 4a 30w 55-300hfe 8mhz
    512-KSA940TU pnp to-220 bce 150v 1.5a 25w 4mhz 40-140hfe $0.54
    neither side is going to come close to an amp of current, no less 4 amps


    awr-156 q2 2sc1735 100v 0.5a 0.8w 55-300hfe 130mhz
    512-KSC2383YTA to-92L ecb 160v 1a .9w 50mhz 160-320hfe $0.17
    awr-156 q3 2sa850 100v 0.5a 0.8w 55-300hfe 130mhz
    512-KSA1013YBU to-92L ecb 160v 1a .9w 50mhz 160-320hfe $0.17 (R=60-120, O=100/200, Y=160/320)


    awr-156 Q5 2sd712 512-KSC2073TU
    awr-156 q6 2sc945a eCb 50v .15a .25w 300mhz 40-700hfe
    512-KSC2383YTA to-92L ecb 160v 1a .9w 50mhz 160-320hfe $0.17

    awr-156 d8 mz-140 512-1N5244B Fairchild 14 V, 0.5W Zener
    awr-156 d9 mz-130 512-1N5243B Fairchild 13 V, 0.5W Zener

    awr-156 d10 LZ230 512-1N4748A Fairchild 22 V, 1.0W Zener
    awr-156 d11 LZ230 512-1N4748A Fairchild 22 V, 1.0W Zener




    awr-156 c19,c20 4.7uf 50v 647-UPW2A4R7MDD 4.7uf 100v $0.14
    awr-156 c17,c18 47uf 16v 647-UPW1V470MED 47uf 35v $0.16
    awr-156 c24,c25 47uf 25v 647-UPW1V470MED 47uf 35v $0.16
    awr-156 c11,c12,c15,c16 220uf 80v 647-UPM2A221MHD 220uf 100v $1.02 ea
    awr-156 c13 220uf 35v 647-UPW1V221MPD 220uf 35v $0.28
    awr-156 c23 2200uf 35v 647-UPW1H222MHD 2200uf 50v $1.49 ea

    ---mouser parts list importer --- cut/paste data entry text block ------
    512-KSC2073TU
    512-KSA940TU
    512-KSC2383YTA
    512-KSA1013YBU
    512-KSC2073TU
    512-KSC2383YTA
    512-1N5244B
    512-1N5243B
    512-1N4748A|2
    647-UPW2A4R7MDD|2
    647-UPW1V470MED|4
    647-UPM2A221MHD|4
    647-UPW1V221MPD
    647-UPW1H222MHD

    right now there is a month lead time on the backordered ksc2383YTA, so ksc2383OTA can be substituted.

    about 14 bucks in parts, with another 6 to 8 for shipping.
     
    Last edited: Jan 8, 2015
  8. danyost

    danyost New Member

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    Parts list for AWR-156

    Understood. What are the 512-1N4748A|2 for?
     
  9. markthefixer

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

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    D10, D11 got lost in the shuffle, literally.... 22v 1 watt zeners...

    awr-156 d10 LZ230 512-1N4748A Fairchild 22 V, 1.0W Zener
    awr-156 d11 LZ230 512-1N4748A Fairchild 22 V, 1.0W Zener


    I edited them back into the list on that post..
     
  10. danyost

    danyost New Member

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    Thanks Mark!
     
  11. GTS Dean

    GTS Dean New Member

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    I'm late to the party here, but what a great thread this was/is and extremely helpful to me!

    I recently picked up an SX-980 from eBay from a highly rated seller. Very clean, but despite being 're-cap'd' it still has some issues. Phono 1 had a broken ground cap (easy fix) but the protection circuit was tripping when the jams got too serious. I downloaded the manual and adjusted the power amp center current, the idle current and the power meters - all successfully. Still tripping the protection circuit though, but somewhat improved.

    One of Mark's helpful suggestions was to look at the terminals at the top of the boards for oxidation/overheating signs, and Bingo! They were all pretty nasty looking. I didn't have a pencil eraser handy, but I made use of some very fine emery board sticks (about 3mm square) for plastic model finishing. This touch-up, followed by DeOxIt on the plugs made a HUGE improvement. I was able to play extended high volume music at steady 20-60W and touching 80W output levels at about all the SPL my ears could stand. The protection circuit tripped one time for 5 sec. over about 15 minutes.

    This site is fabulous and the members are super-knowledgeable and the resources share freely.

    Thanks!

    SX980 amp terminals 8x6.jpg
     

     

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  12. zebulon1

    zebulon1 Getting behind on work. I need help? Subscriber

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    The reason for the eraser is to preserve the plating on the pins. Once that is gone the elements have their way. I'm afraid you maybe doing this pin cleaning again sooner that you would like.
    Maybe some sort of inhibitor, like the paste they use on car connectors?
     
    Last edited: May 31, 2018
  13. GTS Dean

    GTS Dean New Member

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    I have a tube of dielectric grease on hand that I use on my cars. The pins actually looked like tarnished silver.
     
  14. zebulon1

    zebulon1 Getting behind on work. I need help? Subscriber

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    There are these if it needed. I think they fit the trace spacing:
    I can't find the recent thread were a member manufactured a replacement board for one of the higher powered receivers. He used these terminals. Digikey
    Pioneer did use a simular terminal in the Spec 4's

    [​IMG]
     
  15. GTS Dean

    GTS Dean New Member

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    Can anyone point me to a tool that will replicate this terminal connection? I have some speakers that need re-wiring. terminal wrap.jpg
     
  16. zebulon1

    zebulon1 Getting behind on work. I need help? Subscriber

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    Last edited: May 31, 2018
    GTS Dean likes this.

     

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  17. GTS Dean

    GTS Dean New Member

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    I've found a couple of hot spots on the receiver that I'd like to share. It looks like there is one REALLY hot resistor that needs some investigation, along with a previous splice point near the tuner section. The upper right corner is of the R channel amp board. Both sides are pretty equal in temp.

    980 collage.JPG
     
    Last edited: Jun 7, 2018
  18. markthefixer

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

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    That is R11, 2700 ohms 1 watt. It's point in the design is intended to get hot, it is dissipating a little over 1/2 of a watt and it is a 1 watt resistor.

    It supplies the bias current / voltage for the D9 13v zener diode, and whatever is drawing current at -13 volts from pin 28 of the power supply.

    The way a zener diode works to keep a set voltage ACROSS itself is to pull more current until either the voltage is correct, or it burns itself out - thus more draw makes a cooler D9 but a hotter R11. And NO I don't think pin 28 is pulling inordinate amounts of current. It supplies 8 mA (0.008Amp) to run the meter circuitry, and there are no capacitors OFF the board to leak and pull more current.

    You'll have to describe the splice more accurately to comment upon it, where each end of each wire is connected to.

    The service manual will supply the necessary enlightenment for the description.
     
  19. GTS Dean

    GTS Dean New Member

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    Here's a better photo of the splice. It has 4 wires that tie to one white. It drops down below the tuner knob to a terminal below the tuner section.
    hot splice.jpg
     

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