1. Time for some upgrades in server hardware and software to enhance security and take AK to the next level. Please contribute what you can to sales@audiokarma.org at PayPal.com - Thanks from the AK Team
    Dismiss Notice

Scott LC-21 new pot and balance problem

Discussion in 'Tube Audio' started by Tenoates, Jun 11, 2018.

  1. Tenoates

    Tenoates New Member

    Messages:
    6
    hi,

    My LC-21 needed a new pot because it was becoming noisy with unbalanced outputs. I cleaned it a few times to no effect so I bought one off eBay from a seller who says his to be a drop-in replacement. The only differences from the original pot is this is a twist to turn on (rather than pull) and there are 5 taps (3+2) , instead of 4/ side on the original (3+1) . He told me to measure the 2 taps and use the ones that's were closest to the original.

    I installed the new pot using the notes I made before desoldering and confirmed the wiring on the original LC-21 assembly manual. Double checked everything and powered up.

    The first LP I played had good, clean, balanced sound but then the left channel turned off and I now only have sound coming from the right channel. If I move the balance to L, I get no sound except when I turn the pot to full. That's when sound comes out of the left channel.

    I double checked all the solders and connections again but everything seems to be correct. I swapped preamps to be sure it's not the amp and I confirmed it's the LC-21.

    What should I check to fix this?

    TIA!
     

     

    Please register to disable this ad.

  2. Patrice B

    Patrice B AK Subscriber Subscriber

    Messages:
    2,243
    Location:
    Montréal, Canada
    Bad solder joint maybe? Re-check your wiring and make that there isn't any shorts.
     
  3. Tenoates

    Tenoates New Member

    Messages:
    6
    I checked for shorts yesterday and found none. I did measure the 22k and 220k resistors leading to the pot and they were lower than what they should be. I'll probably rewire it again once I get new resistors
     
  4. Patrice B

    Patrice B AK Subscriber Subscriber

    Messages:
    2,243
    Location:
    Montréal, Canada
    If I understand correctly: it was ok and then, left channel cut off? Maybe time do Deoxit...
     
  5. Tenoates

    Tenoates New Member

    Messages:
    6
    It's a new pot so I don't think cleaning will work.
    After I installed the new pot, both channels worked but after a while, there is no sound from the L channel but R channel has sound.

    If i turn the volume all the way up, the sound comes back to the L channel
     
  6. Dandy

    Dandy Super Member

    Messages:
    4,532
    Location:
    North West, UK
    You don't mention the source and quality of the pot. eBay sellers offer variable quality products. Why not clean it with some switch cleaner anyway?
     

     

    Please register to disable this ad.

  7. gullaz

    gullaz Active Member

    Messages:
    165
    Location:
    Bologna, Italia
    From what you describe it might be that one section of the new pot is defective. Check it with an ohmmeter on different wiper positions.
     
  8. Tenoates

    Tenoates New Member

    Messages:
    6

Share This Page