Fender Blues Deluxe Reissue broken/non-functional brightness switch - help!

Discussion in 'Amp Tech Center' started by tortured turnip, Apr 27, 2020.

  1. tortured turnip

    tortured turnip TDPRI Member

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    Hi TPD, was wondering if anyone out there knows about this mod to a brightness switch.

    I've recently picked up a Fender Blues Deluxe (reissue), and noticed that the brightness switch does nothing. I've played around and the switch as far as I can tell has no effect on tone, or any other parameter. Looking at the PCB it's clearly been modded - a resistor jumping from R9, and the track to C53 is cut (see picture attached). This is all just under S1 (the brightness switch) and I can't see any other obvious mods to the PCB, but equally i'm not sure if any other caps etc. have been replaced.

    I'd really like to reverse this! Cheers

    IMG_5634.jpg
     
  2. jrblue

    jrblue Tele-Afflicted

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    I haven't studied BD mods, and I'm not going to guess; should be easy to get the schematic and check everything.
     
  3. Dacious

    Dacious Poster Extraordinaire

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    I'd say maybe the trace on the board broke and someone bypassed it.
     
  4. Lowerleftcoast

    Lowerleftcoast Tele-Holic

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    Does the channel switch work?

    With C53 being cut the channel switching would not function properly without some other connection to bypass that cap.

    Is R52 still in place?

    The added resistor (R9 to Cap ground) essentially parallels R52. It may replace it.
     
    Last edited: Apr 27, 2020
  5. tortured turnip

    tortured turnip TDPRI Member

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    Channel switching still works in the sense that the amp switches to the drive channel when you press the switch on the amp, but I don't have a footswitch for the channel selector so not sure if channel switching with the added footswitch still works
     
  6. Jon Snell

    Jon Snell Tele-Meister

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    Not sure where the addition goes to except probably ground.
    R9 feeds the rest of the stages as does C53.
    Here's the circuit ... Screenshot 2020-05-06 at 21.02.31.png
    The additional resistor goes to ground. Makes no sense at present.
     
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  7. Lowerleftcoast

    Lowerleftcoast Tele-Holic

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    I meant the bright switch not the channel switch. Sorry.:oops:

    If the trace was cut at C53 the bright switch would only pass signal in one position. I doubt this was done as a mod. My bet is the relay failed. Instead of replacing the relay someone tried to bypass the relay and tried to adjust the bright cap RC filter to have a more pleasant sound. To put it back to stock the fix would need to be reversed. Probably need to address the relay as well.
     
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  8. guspac88

    guspac88 Tele-Meister

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    Agreed with Lowerleftcoast, if your switch isn't cutting signal in one position someone has really mucked this thing up trying to get around what would have been a quick fix. I didn't know anyone would grind a trace off like that :eek: best bet is to get it to stock at this point. Someone correct me if I'm wrong, but I suggest you run a wire where the trace would have been, because I don't know of a better way to repair that ground out spot. The alternative is copper tape, but copper tape over exposed traces isn't something I'd want my signal going through personally.
     
  9. Jon Snell

    Jon Snell Tele-Meister

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    Agreed with Lowerleftcoast. There will be no signal passing when the relay is relaxed at present as C53 passes the signal at that point.
    Use a fibreglass pen to remove about 1/8" of the varnish covering the cut track on each side.
    Tin the bare copper track and use a resistor leg to bridge it and solder it in place.
    Remove the errant resistor and if needed fault find the relay if it doesn't work. They are very inexpensive but that means removing the PCBoard from the chassis.
     
  10. elpico

    elpico Tele-Holic

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    I can't find a drawing that matches your picture of the board. If you have one can you send me the link?

    edit: oh I missed that this was the reissue version. got it.
     
    Last edited: May 7, 2020
  11. tortured turnip

    tortured turnip TDPRI Member

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    Really appreciate the advice from you all - will let you know how I get on
     
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