DSL40c - weird issue with green channel

Discussion in 'The Workbench' started by ledvedder, May 25, 2019.

  1. ledvedder

    ledvedder Active Member

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    I'm experiencing a weird issue on the green channel that's very sporadic. The amp will sound great for a while, both the green and red channels. Then, suddenly, when switching from red to green, the volume on the green channel drops significantly. But sometimes, it will also increase a lot and be distorted. Meanwhile, the red channel still works great. Sometimes, turning the amp off and back on fixes the green channel for a little while, but it always seems to come back again. This happens when using the Marshall footswitch to change channels, or using the button on the amp.

    Where should I start to look? Tubes, circuitry, somewhere else?
     
  2. ampmadscientist

    ampmadscientist Well-Known Member

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    Look for arcing burning on the circuit board between traces.

    Get in touch with your forum brother:
    http://www.marshallforum.com/members/the-heald-graduate.56054/
    He may have some pointers for you on this amp.

    [​IMG]
     
    Last edited: May 26, 2019
  3. The Heald Graduate

    The Heald Graduate New Member

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    hi ,

    Are you using the crunch on channel 1 or just normal clean gain on channel 1. its important to note the volume knob is it working with less effect or making no
    difference>>>?
    Did you ever notice any crackling noises ,, the problem you are having means the amp needs to be visually inspected and that means opening it up and checking some resistances and voltages. That is not a safe thing to do if you have never worked on high voltage gear before, it can KILL you if not done safely.

    Kevin.
     
    Last edited: May 31, 2019
  4. Len

    Len Well-Known Member

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    One of 3 things:
    - Bad tubes
    - Dirty tube sockets
    - Cold solder joints at the tube sockets
     
  5. solarburnDSL50

    solarburnDSL50 Well-Known Member

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    I'd check tubes first. Eliminate that. Course there are cords, pedals etc too. Do the basics first.

    Then see where it's fucked. Lots of great techs here.
     
  6. ledvedder

    ledvedder Active Member

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    Thanks guys. I've tested the tubes and all cables with my other amps. No issues there. What's weird is that I haven't been able to reproduce the issue since last week. I guess I'll keep trying.
     
  7. tmingle

    tmingle Active Member

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    There is a thread here somewhere describing an IC chip that becomes intermittent.
    http://www.marshallforum.com/threads/marshall-dsl-40c-issue-need-your-help.91497/

    Mine does this occassionally. After looking at the schematic, I believe it may be possible to rewire the channel switching to foot switches. I haven't had time to investigate further, but all the channel switching, reverb & efx loop seem to be turned on & off by relays.
     
  8. tmingle

    tmingle Active Member

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