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Need Silverface Twin Master Volume pot with DPST pull switch

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  • #16
    So, exactly what is wrong with the original control?

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    • #17
      I have a '79 UL Twin waiting on time to rehab it here, and decided to look at it. Not only is there a DPST switch attached, there is an extra tap! Looking at the schematic the other switch function lifts the tank input in the reverb circuit.
      twin_reverb_sf_135.pdf
      Last edited by Bill Moore; 08-12-2019, 09:22 PM.

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      • #18
        I buy these but they only come in 500K and 250K.

        https://www.tubesandmore.com/product...5-bushing-dpdt

        Being CTS it's easy to swap the wafer for a 1M, so I buy extra regular 1M CTS pots just for the wafer if I don't have a spare in my stash.

        Oh ya, I also swap the shaft for whatever kind I need.

        HTH.
        If it ain't broke I'll fix it until it is...
        I have just enough knowledge to be dangerous...

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        • #19
          Originally posted by galaxiex View Post
          I buy these but they only come in 500K and 250K.

          https://www.tubesandmore.com/product...5-bushing-dpdt

          Being CTS it's easy to swap the wafer for a 1M, so I buy extra regular 1M CTS pots just for the wafer if I don't have a spare in my stash.

          Oh ya, I also swap the shaft for whatever kind I need.

          HTH.
          While none of the replacement pots have that tap for the 120pF cap, no big deal, as placing one from CW to W terminals pretty much does the same thing. I hadn't seen this pot before......nice to see, and knowing you can do the wafer and shaft swaps, being CTS.
          Logic is an organized way of going wrong with confidence

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          • #20
            I wonder if different eras of Fenders had a different rake angle on their control panel? As some seem to have more room for such pots etc than others.
            My band:- http://www.youtube.com/user/RedwingBand

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            • #21
              Originally posted by Bill Moore View Post
              I have a '79 UL Twin waiting on time to rehab it here, and decided to look at it. Not only is there a DPST switch attached, there is an extra tap! Looking at the schematic the other switch function lifts the tank input in the reverb circuit.

              Yes, that´s the one.

              No big deal with the tap which best case adds buzz but I still need two switches: one to send "strong" reverb tank drive signal to last Reverb channel triode to overdrive it and the other to apply a "warmth" attenuator so signal is not buzzy ...tyalk about conflicting priorities.

              As said before, absolute worst case I will get a "physically perfect" spdt pot and add a 5V relay fed from rectified 6.3V or two plain switchless 1M CTS pots and try some surgery.

              Thanks again.
              Juan Manuel Fahey

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              • #22
                As the MV is being used set high, thereby making power tube gk diodes (rather than the 3rd gain stage) the most significant clipping point, it may be feasible to move the ‘warmth’ circuit back so that it’s part of the boost circuit, so that the one switch can actuate both.
                Just need to do the math / work out a circuit and component values so as to retain the same transfer function. I guess spice etc might be useful here.
                My band:- http://www.youtube.com/user/RedwingBand

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                • #23
                  Thanks

                  I don´t simulate but use pencil and paper and know the Math, so no big deal

                  The problem is that that RC net is not only "warmth" , but also a strong level attenuator: we are adding a 12k load to a 100k plate resistor; if I avoid it, pulling Boost will also cause a huge volume jump upwards.

                  Since this guy is SO used to his sound, I must try to keep things as unchanged as possible.

                  Thanks again.
                  Juan Manuel Fahey

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                  • #24
                    Juan,
                    Have part / Can help.
                    Please wait for my PM.
                    Tom
                    Click image for larger version

Name:	1M W Tap & DPST Pull SW.jpg
Views:	1
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ID:	854548
                    PS: Very strange twist of fate that I tripped across this thread during a google part search for another project.

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                    • #25
                      Really good to see you Tom.
                      Everyone has missed your participation.
                      And you could return if it was the troll issue that put you you off, so...
                      Don't be a stranger.
                      Even if you have issues with forum policy sometimes there's still common interests here.
                      Respectfully,

                      Chuck

                      P.S. How are your code breaking skills
                      "Take two placebos, works twice as well." Enzo

                      "Now get off my lawn with your silicooties and boom-chucka speakers and computers masquerading as amplifiers" Justin Thomas

                      "Being born on third base and thinking that you must have hit a triple is pure delusion!" Steve A

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                      • #26
                        Originally posted by Tom Phillips View Post
                        Juan,
                        Have part / Can help.
                        Please wait for my PM.
                        Tom
                        [ATTACH=CONFIG]54723[/ATTACH]
                        PS: Very strange twist of fate that I tripped across this thread during a google part search for another project.
                        Thanks a lot.
                        Looks like THE REAL THING, huh?

                        Like we say here: "happier than dog with two tails"
                        Juan Manuel Fahey

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                        • #27
                          Originally posted by Chuck H View Post
                          Really good to see you Tom...
                          Thanks Chuck. When time allows I'll respond in the members only lobby & let you know what's going on with me.


                          Originally posted by J M Fahey View Post
                          Thanks a lot.
                          Looks like THE REAL THING, huh?
                          Like we say here: "happier than dog with two tails"
                          Juan,
                          Did you receive my PMs about the pot? I sent you two PMs. If you
                          responded, I did not receive your message.

                          Cheers,
                          Tom
                          Last edited by Tom Phillips; 08-19-2019, 08:18 PM.

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                          • #28
                            Sorry, false start. This one is SPST.

                            Click image for larger version

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Views:	1
Size:	1.88 MB
ID:	854590

                            Click image for larger version

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Views:	1
Size:	1.88 MB
ID:	854591
                            Last edited by Tone Meister; 08-19-2019, 11:30 PM.

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                            • #29
                              I Needs one too

                              Originally posted by Tom Phillips View Post
                              Juan,
                              Have part / Can help.
                              Please wait for my PM.
                              Tom
                              [ATTACH=CONFIG]54723[/ATTACH]
                              PS: Very strange twist of fate that I tripped across this thread during a google part search for another project.
                              I need one too if anyone has one available.

                              Comment


                              • #30
                                Just discovered this thread, as I am in search of one as well. Here is a link to a supplier. It doesn't LOOK the same, but says it'll work in this application.

                                When you get to this page, choose "find in page" with your browser to locate it.

                                https://www.amprepairparts.com/fenderpots.htm

                                Part #P-DPPS-A1M

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