Dsl40c Fx Loop Issue

Discussion in 'The Workbench' started by Nexodus2, Jan 10, 2017.

  1. Nexodus2

    Nexodus2 New Member

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    Good Morning All,

    I noticed a new issue with my otherwise great DSL 40C amp. Recently after traveling with my amp, I noticed that the volume on the clean channel dropped (volume at 10, gain 10, crunch ON would cause a very trebly scratchy sound, but the sound wasn't full at all).

    The other channels, wouldn't crunch, and the sound just seems very tinny and almost harsh. After some research (travel + floors sanded and amp cover was off when we returned), I assumed debris in the FX loop may be the problem. I did the jumper test and switched the loop ON and volume roared back (still very tinny, but higher volume). I removed the jumper, and with nothing plugged in the on and off button almost acts like a boost.

    The amp is a year and a few months old, has never been retubed, but is recreationally used.

    Any idea what would cause the FX loop ON to increase volume without anything plugged in? Any idea why when it's in the OFF position it would decrease volume?

    Finally, if this is beyond a tube change/biasing or simple ribbon cable fix, does anyone recommend any amp repair services in North Texas? (North of Dallas).

    Thank you!
     
  2. Micky

    Micky Well-Known Member VIP Member

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    First thing to check is that the ribbon connecting cables are all tight and seated into their respective connectors.
    Next I would try some Deoxit in the switch itself.
    Does the switch do it with the jumper plugged in?
     
  3. Nexodus2

    Nexodus2 New Member

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    Thanks for the reply Micky, that's correct, the jumpers plugged in or out do not seem to have an effect. I used a contact cleaner on the IN and OUT ports with the jumpers and sprayed the switch, but I didn't use deoxit. I'll open it up tonight and look at the ribbon cable connections, and see if I can snag a few pictures from the inside.
     
  4. Nexodus2

    Nexodus2 New Member

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    Hey Micky sorry for the delayed response.

    I opened the amp up and noticed a yellow substance around the caps, the cables and more. I assume that's glue to hold stuff in place. I used deoxit on the switch, the send and receive jacks and took photos too, I'll try and upload them. On clean Channel without crunch I had to turn gain and volume up to 10:00 to get any sound and it sounded awful. Once I put fx loop on and crunch it sounded better but the quality wasn't nearly as good as it was.

    Do you know if the FX loop button works without any input output plugged in? That would isolate the button and not the jacks.

    Would tubes fix this problem?

    I'm in dallas Texas and amp repair is few and far between. Thanks for any help
     
  5. Nexodus2

    Nexodus2 New Member

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    I can't upload pictures from the iPhone because size is too big
     
  6. Nexodus2

    Nexodus2 New Member

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    I'm not sure how the forums work here, does posting bump to the top?
     
  7. Micky

    Micky Well-Known Member VIP Member

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    Generally yes.
    In order to post photos, it may be best to use photobucket or imgur, where you can upload a large photo then post a link to it or embed the link here.
    Sorry I have not been too helpful as of late, wicked busy here at work and no access to my 40C in a while...
     
  8. Len

    Len Well-Known Member

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    I'd personally change tubes first.
     

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