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SX-780 Volume Pot

Discussion in 'Pioneer Audio' started by rave0035, Nov 12, 2017.

  1. rave0035

    rave0035 Disassemble first, ask questions later.

    Messages:
    623
    Location:
    Twin Cities, MN
    Hi - my SX-780's pots n' switches have given me a lot of trouble since it came off the bench. The volume pot needs cleaning every few months, and has now developed a 'dead spot' near the low end of the scale.

    Anybody replace the volume pot in these? Are replacements available?

    Mike
     

     

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  2. rave0035

    rave0035 Disassemble first, ask questions later.

    Messages:
    623
    Location:
    Twin Cities, MN
    Bumping this... my research has still not found an available replacement that doesn't involve some mods. Anybody? I know this is a common failure in these otherwise awesome amps.

    Mike
     
  3. deltalight

    deltalight AK Subscriber Subscriber

    Messages:
    253
    Location:
    Minneapolis
    The SX-780 vol pot has a loudness tap. Replacements are readily available on evilbay.
     
  4. rave0035

    rave0035 Disassemble first, ask questions later.

    Messages:
    623
    Location:
    Twin Cities, MN
    Thanks - plenty of salvaged units on fleabay, but was hoping to find a new unit given that these things crap out so often. Sounds like that might not be realistic.

    Mike
     
  5. Watthour

    Watthour Electron Rancher - JS3600

    It's not Realistic, it's Pioneer. Realistic used the American Motors philosophy of using everyone else's surplus and rejects.

    You can either retrofit in a "standard" unit without a loudness tap, or retrofit something like this into the chassis:

    https://www.amazon.com/Quickbuying-Potentiometer-Control-Stereo-Loudness/dp/B072R3FJ5S/
     
    Last edited: May 6, 2018
    merlynski likes this.
  6. zebulon1

    zebulon1 Building a new bench. Finally! Subscriber

    Messages:
    4,918
    Location:
    Las Vegas Nevada
    Hey, I have a soft spot in my audio heart for the Realistic brand. :) I really do.

    Back to the thread

    There are a few threads on replacing the volume pot with the loadness tap here on AK somewhere.
     

     

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  7. larryderouin

    larryderouin Turn it UP, POP? PLLUUEEEZZZZZEE Subscriber

    Messages:
    21,908
    Location:
    Glen Burnie Md.
    Watt; He might be too young for the AMC analogy.:rolleyes: How about DeLorean instead. The 1st batch used a Peugeot-Renault-Volvo "Douvrin" V6. Now THAT is a MUTT!
     
  8. Watthour

    Watthour Electron Rancher - JS3600

  9. rcs16

    rcs16 Super Member

    Messages:
    4,076
    Location:
    Baldwin, Ontario, Canada
    Chances are slim in finding a new part. basically have to take your chances with a used part or do the other mods as suggested.
     
  10. zebulon1

    zebulon1 Building a new bench. Finally! Subscriber

    Messages:
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    Location:
    Las Vegas Nevada
    One mention about the Realistic banter, that Realistic/Tandy contracted out the designs and manufacturing. The STA-2100 was made by Foster and used spec'ed out parts designated by Pioneer. In many cases the spec'ed parts were also Pioneer vendors. Remember the 2100's Toroidal transformer law suit?
    There might be a cross to a higher end Realistic unit?
    Worth a shot :dunno:
     
  11. Watthour

    Watthour Electron Rancher - JS3600

    Another option would be to repair/restore the original pots. Unless the carbon traces are worn through, there isn't much else which cannot be repaired, even the bifurcated wipers and bushings.
     

     

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  12. zebulon1

    zebulon1 Building a new bench. Finally! Subscriber

    Messages:
    4,918
    Location:
    Las Vegas Nevada
    MTF notes:
    sx-780: acv-161 dual 100k, log (audio) taper, loudness tapped for pcb mount , NO detents

    also used in:
    sx-450, sx-550,
    sx-580, sx-680, sx-780, sx-880
     
  13. rave0035

    rave0035 Disassemble first, ask questions later.

    Messages:
    623
    Location:
    Twin Cities, MN
    Thanks, all! I might get a replacement and give it a shot. Never tried my hand at restoring a pot... not even sure where to start there.

    Mike
     

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