SX-1980 blown cement resistor R101 20W

Discussion in 'Pioneer Audio' started by omri617, May 11, 2018.

  1. omri617

    omri617 Super Member

    Messages:
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    Hi
    During the past year , I had to replace twice the cement resistor R101 on AWR-154
    The symptom of the receive quit working is it had a delay turning on when levering the power switch up
    No blown fuses , thermal fuse ok also
    What can cause this ?
    220V unit .
    Note - Awr 155 & Awr 154 use different resistance but same wattage
     

     

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  2. mattsd

    mattsd AK Subscriber Subscriber

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    Usually one of two things, either the soft start relay is not engaging at all, or it is engaging but the contacts are pitted or have a large carbon build up on them, increasing resistance between them and causing the receiver to pull power through the resistor. When it first starts up, does it click right after the power switch clicks?
     
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  3. omri617

    omri617 Super Member

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    There’s a click 4 seconds or so after switch is on.
    I can’t recall hearing another one before it
     
  4. zebulon1

    zebulon1 Getting behind on work. I need help? Subscriber

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    It's only a split second before the soft start relay engages. You almost have to lay your finger on it or watch it while flipping the power switch. The click of the relay is darn near the click of the switch.
    If its working correctly.
     
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  5. QSilver

    QSilver Super Member

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    1,182
    You could try turning it on at the wall instead of the power switch if the wall socket is quieter. You might hear the relay then? I've done that with the SPEC-4.
     
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  6. kevzep

    kevzep Its all about the Music Subscriber

    Sounds to me as the others have suggested, you need a new soft start relay. It obviously not coming on quick enough and the power is running through the resistor for too long..
     
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  7. markthefixer

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

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    If the soft start relay hasn't been replaced, it would be the original, and burned / resistive contacts are a certainty.

    This level of resistance is hard to measure with a 2 wire DMM ohm scale.

    Do yourself the favor, and replace it - it will be a LITTLE bit of work changing to 24v from the 48v circuit because the 48v relays seem to have become unavailable.
    The 24v relays are plentiful and reasonably priced.



     
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  8. kevzep

    kevzep Its all about the Music Subscriber

    I was lucky enough to get a 48V speaker and protection relay last year...You might get lucky..
     
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  9. mattsd

    mattsd AK Subscriber Subscriber

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    From my restoration thread:

    The only available 48V LY1 relay has large terminals that require you to enlarge the holes on the board for the relay. Somewhat messy and doesn't look good underneath, no matter how hard you try. Definitely do the mod as Mark suggested, and it has the added bonus of removing some thermal load from the board, as R102 dissipates about 1W.
     
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  10. kevzep

    kevzep Its all about the Music Subscriber

    Ah yes, thats what I did!! I used your restoration thread as a resource, it is the best idea......works very well, I used your BOM, did the trick nicely.......
    I ordered the 48V speaker relay and had to wait 8 weeks for it!!
     
    Last edited: May 12, 2018
  11. omri617

    omri617 Super Member

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    1,155
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    I looked in my relays compartment and I found these new ones :

    MY2-02 (48V) - 3 pieces
    MY4-02 (24V)
    LY1-0 (24V)

    MY2-02 is suitable for protection
    Anyone got the 48V s.s relay for sale? :$
     

     

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  12. kevzep

    kevzep Its all about the Music Subscriber

    Like the guys said, use the 24V and do the small mod, this is what I did to the one I restored, its a drop in and an easy mod...
     
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  13. QSilver

    QSilver Super Member

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    I would go with the 24V relays as these mean you cna run them off the 24V power rail instead of using a resistor to drop the 80V rail to 48, which ends up giving you one very hot resistor. Heat is the biggest enemy here so I think that's another reason why converting to 24V made sense. Less heat.
     
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  14. omri617

    omri617 Super Member

    Messages:
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    Sounds clever
    I will do it
    Thanks guys
     
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  15. omri617

    omri617 Super Member

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    Done. went with the 24V relay and the modification suggested. The new realys sound quieter than the old ones.
    Thanks a lot
     
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  16. kevzep

    kevzep Its all about the Music Subscriber

    Nice work!! How fast does it click over after you power it on, it should be very very quick....
     

     

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  17. omri617

    omri617 Super Member

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    between 3 - 4 seconds I assume.
    Faster than before that's for sure and the relay click sounds softer.
     
    Last edited: Jun 17, 2018

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