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Blues junior III tube socket

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  • Blues junior III tube socket

    Any suggestions on this repair?? Is point to point my best option?? I haven't been able to find a replacement board
    Click image for larger version

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    Fender-Blues-Junior-III-Schematic-Rev-D.pdf
    If you don't know where your going any road'll take you there : George Harrison

  • #2
    Originally posted by shortcircuit View Post
    Any suggestions on this repair?? Is point to point my best option?? I haven't been able to find a replacement board
    [ATTACH=CONFIG]54324[/ATTACH]
    [ATTACH]54325[/ATTACH]
    First, I would carefully de-solder the remaining solder terminals, then re-solder, using leaded solder, NOT lead-free. Pins 1, 6 & 8 are NOT used on the EL-84 tube. Granted, you've lost the mechanical integrity of Pin 1. If you're careful with the de-solder & re-solder operation, you should still have solid mechanical integrity on the remaining pins. This PCB is one of the many Fender has produced, with extremely poor foil adhesion. Those pads and traces lift with the greatest of ease. You don't need a replacement PCB.
    Logic is an organized way of going wrong with confidence

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    • #3
      That would not warrant a board replacement, it's a common failure corrected by soldering in bits of solid wire or snipped component leads to replace what has burned. What concerns me most here is why did pin 1 of a EL84 burn when it should have no connection?
      It's weird, because it WAS working fine.....

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      • #4
        Originally posted by Randall View Post
        That would not warrant a board replacement, it's a common failure corrected by soldering in bits of solid wire or snipped component leads to replace what has burned. What concerns me most here is why did pin 1 of a EL84 burn when it should have no connection?
        The owner had a heavy hand when they tried replacing tubes , popped the connections,including some pads on both v4 and v5 . On a 1st attempt to re seat them that pin 1 pad lifted out with the iron tip . Now I will follow nevetslab and Randall advice and remove and replace lead free, add trace jumpers where needed , thanks MEF is the best !!!
        If you don't know where your going any road'll take you there : George Harrison

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        • #5
          Should you change your mind there are PCBs available e.g. https://reverb.com/item/10803881-fen...-points-by-mox
          Last edited by nickb; 07-15-2019, 07:54 PM.
          Experience is something you get, just after you really needed it.

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          • #6
            Originally posted by nickb View Post
            Should you change your mind there are PCB available e.g. https://reverb.com/item/10803881-fen...-points-by-mox
            Nice work nickb, and very reasonably priced.
            Originally posted by Enzo
            I have a sign in my shop that says, "Never think up reasons not to check something."


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            • #7
              Seen 2 others on Reverb that didn't look right, didn't see this one, looks like it would work, thanks nickb. Have repair done but it's not re assembled yet. I noticed in the pic a resistor connected to R51 ??? why ??
              Click image for larger version

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              If you don't know where your going any road'll take you there : George Harrison

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              • #8
                Originally posted by g1 View Post
                Nice work nickb, and very reasonably priced.
                Aw shucks. Thx
                Experience is something you get, just after you really needed it.

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                • #9
                  Originally posted by shortcircuit View Post
                  Seen 2 others on Reverb that didn't look right, didn't see this one, looks like it would work, thanks nickb. Have repair done but it's not re assembled yet. I noticed in the pic a resistor connected to R51 ??? why ??
                  [ATTACH=CONFIG]54332[/ATTACH]
                  It's a common tweak to lower the bias current. Nothing to do with the tube PCB.

                  I have two other other versions on Reverb. One is for the early V1 "Green Board" FBJs. The other "premium version" is also for the "Cream" board FBJ's but comes with gold sockets and an adjustable bias mod kit.
                  Last edited by nickb; 07-15-2019, 08:07 PM.
                  Experience is something you get, just after you really needed it.

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                  • #10
                    Originally posted by nickb View Post
                    Should you change your mind there are PCBs available e.g. https://reverb.com/item/10803881-fen...-points-by-mox
                    Excellent! I was wondering if you were going to make these available. I thought I remembered reading that they were only available to UK buyers on bmamps once upon a time.
                    I just saved your reverb shop in hope that one day, you'll be offering the highly anticipated PIC/triac power supply controller as well.
                    If I have a 50% chance of guessing the right answer, I guess wrong 80% of the time.

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                    • #11
                      nickb, BRILLIANT!!!
                      It's weird, because it WAS working fine.....

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                      • #12
                        I think the really bad thing in that pic has not been the mechanical problem with the original welds but with the new ones.
                        I dŽont want to imagine (it may not be the case) the installation of a new board using that same technique.
                        In any case the board maintains its integrity and I would recompose it instead of replacing it. Something of this style:

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                        • #13
                          Originally posted by Pedro Vecino View Post
                          I think the really bad thing in that pic has not been the mechanical problem with the original welds but with the new ones.
                          I dŽont want to imagine (it may not be the case) the installation of a new board using that same technique.
                          In any case the board maintains its integrity and I would recompose it instead of replacing it. Something of this style:

                          [ATTACH=CONFIG]54421[/ATTACH]
                          Thanks for the reply Pedro,the pic in post #1 is pre repair , an attempt to see if re-flow was an option. I'm green but I would never leave anything looking like that. I have since de-soldered and re-flowed the socket per nevetslab's suggstion,but would trust your pics re-trace even further. With pins 1,6,8 all comprimised nickb's replacement board is tempting.
                          If you don't know where your going any road'll take you there : George Harrison

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                          • #14
                            Went back and added re-trace jumpers to suspect looking pins, not much I could do with 1,6, 8 , so I wrapped with a doughnut piece of wire and soldered those, put some corona on them as some sort of adhesive (good/bad/dumba**??) After thought, are these going to break away and float around as shorting doughnuts??(easily removed) . Put in new JJ's , biased at 2.75ma , should be a happy Junior III .
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                            Last edited by shortcircuit; 07-24-2019, 04:26 AM.
                            If you don't know where your going any road'll take you there : George Harrison

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                            • #15
                              IMO, your "glued doughnut" isn't any more likely to cause problems than the original configuration.
                              "I took a photo of my ohm meter... It didn't help." Enzo 8/20/22

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