SX-5580 SX-1050 SMOKING HOT...ON POWER UP

Discussion in 'Pioneer Audio' started by r887661, Sep 10, 2017.

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  1. Stevescivic

    Stevescivic Active Member

    Messages:
    188
    OMG I couldn't comprehend doing that. I had a relative donate me their minty SX-3800 receiver years ago (and since then have recapped it and it is in use today) that was coated with a thin film of smoker's residue. I spent weeks with rubbing alcohol cleaning up everything I humanly could and I was worried about frying components then!

    Do you have a link that thoroughly documents the cleaning method you used? I would love to learn more about it and perhaps apply that to a future units that I purchase...

    Thanks,
     
  2. r887661

    r887661 AK Subscriber Subscriber

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    Ludington, Michigan

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  3. zebulon1

    zebulon1 Back repairing the PL's Subscriber

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    3,995
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    Las Vegas Nevada
    Or an hour in the Las Vegas summer sun :confused:
     
    merlynski likes this.
  4. r887661

    r887661 AK Subscriber Subscriber

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    90
    Location:
    Ludington, Michigan
    Depends on humidity...;-)

    Here is a Sansui AU-717 getting the treatment. Came out of a carpenters workshop, you can guess what it looked like inside...

    Well, all of a sudden I cannot attach pictures...sorry...
     
    Last edited: Sep 21, 2017
  5. r887661

    r887661 AK Subscriber Subscriber

    Messages:
    90
    Location:
    Ludington, Michigan
    Apologies for the delay in updates.

    The DBT worked a treat, better than a variac really. Traced the problem to the large capacitor on the power board that carries the four fuses. With that changed out bulb dims right down on start up and all lights come on with protection relay clicking after four seconds,

    But still work to do. After about 15 seconds there is a loud buzz and the protection relay operates. Quick feel around shows that one of the 22000 80V ACH-056 capacitors is running hot, while the other is cool.

    I am trying to get my hands on some replacement caps. My question here is; does the overheating capacitor indicate a failing cap or problems elsewhere in the system?

    Thanks guys.
     
  6. merlynski

    merlynski Curmudgeon Electronicist Subscriber

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    High Plains, Eastern Colorado
    Likely failed and (electrically) leaking cap. Has it been removed for testing and reinstalled backwards, maybe (by previous owner)? Recheck for correct installation. Check the voltage polarity across it to verify it is correct. One of those caps is the filter for the positive supply rail and the other is for the negative supply rail. The positive rail cap will have its negative terminal screwed to the ground strap, the negative rail cap will have its positive terminal screwed to the ground strap. If it is backwards it is ruined. If installed with correct polarity it has failed. Unless the wiring has been altered problem is not likely to be elsewhere in the system . . .

    EDIT: for clarity
     
    Last edited: Oct 2, 2017
  7. r887661

    r887661 AK Subscriber Subscriber

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    90
    Location:
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    Just removed them and they look to have been wired in properly. Negative terminal on caps is marked BLACK. Just ordered a new set, should be here Friday. Noticed that the back side of the surge protector board was very heavily oxidized. Cleaned it up.

    The one that was running hot is very slightly swollen.

    How do I test a cap once it is out of circuit?
     
  8. merlynski

    merlynski Curmudgeon Electronicist Subscriber

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    98
    Location:
    High Plains, Eastern Colorado
    The swollen one that was hot is bad, good chance the other one, if the same as the bad one, is near end of life as well. I would replace both if it was mine.

    Use your DMM on ohms to check for shorted or leaky caps. Some DMMs have capacitor test functions, most don't go as high as those caps. If you have a bench power supply you can put your voltmeter across the cap and apply DC voltage through a resistor and watch the cap voltage rise, it will rise slower as it approaches the supply voltage and eventually max at the supply voltage. Higher voltage is better but don't exceed the caps max voltage rating. If it does not max very close to the supply voltage you can see the current leakage as a voltage across the resistor. MUST be out of circuit for bench supply testing. ESR meters can be used to test caps as well, some have more functions/ranges than others. These power supply suggestions are mostly for large value (expensive) electrolytic caps, though you can test small caps for leakage the same way. But for the time/labor spent and low cost of most small caps just replace them if suspect.
    Others here may have more good suggestions as well.
     
  9. r887661

    r887661 AK Subscriber Subscriber

    Messages:
    90
    Location:
    Ludington, Michigan
    Great help, thanks. I have them both caps loose on my workbench, plus I just borrowed a friends variac, I assume it supplies DC also. I have ordered two new Caps of identical rating. I have my trusty Fluke 78 as well. Looking forward to finishing work and getting home to carry on trying to restore this 5580

    My set up is:

    Quad 405-2 with 34 pre-amp serving Dalquist DQ10s
    Mitsubishi DA-15DC amp with DA-C20 pre-amp serving Snell CV3s
    Marantz 2325 serving Klipsch KG4s
    Thorens TD 160b MK2 with SME 3009 Series 2 Fixed headshell arm Shure V15III and VN35E stylus
    Technics SL1200 MK2 with Shure V15III and VN35E stylus
    Technics SL-P999 CD player running FO through MSB Link 3 with Full Nelson Upgrade
    Workbench has four BIC America DV62si speakers.
    Panasonic RF-4900 Multiband Receiver
     
    Last edited: Oct 3, 2017
  10. merlynski

    merlynski Curmudgeon Electronicist Subscriber

    Messages:
    98
    Location:
    High Plains, Eastern Colorado
    Nice setup!, and you're welcome! Helping is the heart of AK :)

    Variacs do not supply DC, only AC. Most do not provide isolation from the Mains AC side either, unless specifically designed that way, and they can be very dangerous to the user. You can put a rectifier on the output of the variac to get DC but that can be very hazardous to the user as well. If you connect an electrolytic capacitor to a variac output directly it may overheat and explode.

    P.S. For Sale and Wanted items must be posted in Bartertown per forum rules. They are prohibited in technical forums. (Just a heads-up to avoid moderator intervention)
     
    Last edited: Oct 3, 2017
  11. r887661

    r887661 AK Subscriber Subscriber

    Messages:
    90
    Location:
    Ludington, Michigan
    Interesting all around..yup, 10/4 on the variac...I did some checking and see that it is AC only.

    I'll install the new Caps this weekend and use a heat gun to monitor the temp rise in both. DBT in circuit.

    I will delete my FS and Wanted stuff. I'm already on Barter Town. Thank you for the heads up.
     
  12. r887661

    r887661 AK Subscriber Subscriber

    Messages:
    90
    Location:
    Ludington, Michigan
    OK, so I installed the new Caps and verified everything by comparing with pics I took prior to removing the old ones.

    Using the DBT when I power up the bulb is dim but it slowly brightens up until near full intensity. Protection relay does not cut in. Surge protector main resistor does not heat up at all, good thing. Five fuses on power board all good.

    The new caps are both cool and I can neither see nor smell any sign of distress.

    Where next chaps?
     
  13. merlynski

    merlynski Curmudgeon Electronicist Subscriber

    Messages:
    98
    Location:
    High Plains, Eastern Colorado
    At power on DBT should flash bright and then fade to dim when all is good. I suspect there is still a power supply problem . . .

    How long does it take DBT to get to near full intensity?

    Does the surge suppressor relay (S2) pull in?

    Check and report the power supply DC voltages referenced to ground on:

    Both New 22000mfd caps
    C2-, Negative Rail:
    C1+, Positive Rail:

    Power Supply PCB AWR-104
    Pin 3:
    Pin 5:
    Pin 6:
    Pin 7:
    Pin 8:

    and output DC offset, Power Amp PCB AWH-047
    Left Output, Pin 4:
    Right Output ,Pin 17:

    Do not leave powered on for longer than it takes to make measurements.
    Be careful not to short pins with DMM probe, cover all but the very tip, or attach minigrabbers while power is off.
    Maybe Zebulon1 or MTF or another senior tech will jump in with better ideas or questions . . .?
     
    Last edited: Oct 4, 2017
  14. r887661

    r887661 AK Subscriber Subscriber

    Messages:
    90
    Location:
    Ludington, Michigan
    Thanks Merlynski, just started my day at work but will get on with this as soon as I get home. Will report back then. I really appreciate this willing help and advice. Ian
     
  15. r887661

    r887661 AK Subscriber Subscriber

    Messages:
    90
    Location:
    Ludington, Michigan
    Interesting, started the test and when I went to measure Pin 3 the brown wire was off. So see the results below for 1st and 2nd test (pin three re-connected)

    I am a marine engineer with 28 years of deep sea ship board experience so I find this absolutely fascinating. I really appreciate your help...thank you. Ian
     
  16. merlynski

    merlynski Curmudgeon Electronicist Subscriber

    Messages:
    98
    Location:
    High Plains, Eastern Colorado
    When you were taking the voltage measurements did you have the negative lead (usually black) of the meter connected to ground (chassis) and make the test measurement connections with the positive lead (usually red)? The voltages are way off but the polarities all seem reversed as well . . .
     
  17. r887661

    r887661 AK Subscriber Subscriber

    Messages:
    90
    Location:
    Ludington, Michigan
    Leads were reversed because I only have a red hook-on lead...stupid me...I see the error...
     
  18. merlynski

    merlynski Curmudgeon Electronicist Subscriber

    Messages:
    98
    Location:
    High Plains, Eastern Colorado
    Don't beat yourself up, just one of the hazards of "remote control" trouble shooting :oops:
    I am going to reverse/correct the polarities and repost the results:

    How long does it take DBT to get to near full intensity? 1st test = 10s 2nd test - instant

    Does the surge suppressor relay (S2) pull in? 1st test = no 2nd test = no

    Check and report the power supply DC voltages referenced to ground on:

    Both New 22000mfd caps
    C2-, Negative Rail: 1st test = -32v 2nd test = -0.926v
    C1+, Positive Rail: 1st test = 0v 2nd test = 0v

    Power Supply PCB AWR-104 (all with brown wire re-connected to pin 3)
    Pin 3: +0.943v
    Pin 5: -0.946v
    Pin 6: +2.730v
    Pin 7: -2.786v
    Pin 8: +0.930v

    and output DC offset, Power Amp PCB AWH-047
    Left Output, Pin 4: 0.000v
    Right Output ,Pin 17: -0.109v

    With the DBT instantly bright and the other results I see a problem with the positive 62v power supply, I suspect shorted.
    Unplug from DBT
    With DMM on lowest ohms range test Power Supply PCB AWR-104 pin 3 referenced to ground.
    If it shows 0 ohms (or very close) remove the screw from the positive terminal of C1 and separate and test each of the three wires to check which one is shorted.
    If one is shorted follow it and report where it is connected. They should be going to Power Supply PCB AWR-104 pin 3 and Power Amp PCB AWH-047 pins 1 and 20. The wires going to AWH-047 will be twisted with wires from the negatve side of C2, going to other pins on AWH-047.
     
  19. r887661

    r887661 AK Subscriber Subscriber

    Messages:
    90
    Location:
    Ludington, Michigan
    OK mate got it. I am still at work ( basic 6 x 12 hr days) so should be home in about 2hrs...a bite to eat then I'm at it as per your instructions. Looking forward to it....
     
  20. tsd71

    tsd71 RIP Tom Petty Subscriber

    Messages:
    2,672
    Location:
    New Jersey
    Can you add a pic of both filter caps and how they are now connected.
     

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