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2meg Pot For Gibson Scout Amp

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  • 2meg Pot For Gibson Scout Amp

    I have a GibsonScout amp that I've had since 1966. It has a 2meg audio taper pot in the reverb unit. When I turn it up past 7, it starts to drop out and lose volume, so I assume it's going bad. I decided to replace it, but it seems like 2meg audio taper pots are as rare as hen's teeth. Does anyone know where I can get one? or a substitute that doesn't compromise the original integrity of the circuit?

    Thanks

    Rocky Hill

  • #2
    Have you tried cleaning it?
    "I took a photo of my ohm meter... It didn't help." Enzo 8/20/22

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    • #3
      yes

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      • #4
        Do we have the schematic on this, and like you could post it?

        What pots do you have on hand? If you have a common 1 meg pot, try it in the circuit. It surely cannot harm anything, and if the result sounds OK to you, then it is OK.

        Remember, it is only a guitar amp, not NASA lab gear. You can take wide liberties with the components.
        Education is what you're left with after you have forgotten what you have learned.

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        • #5
          You might contact Torres Engineering and see if they still have them. They used to. It doesn't spec taper in the link, but they use them for guitar, so my bet is that it's audio taper. It might be worth a phone call to find out.

          https://torresengineering.stores.yahoo.net/2megpot.html

          Edit: Here's the schematic:

          Click image for larger version

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          "I took a photo of my ohm meter... It didn't help." Enzo 8/20/22

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          • #6
            I have seen where people have cleaned the carbon track with a pencil eraser ✏️. Many old pots can be taken apart to the point where the inside wafer is completely accessible. If the eraser trick won't get it clean then it might be the carbon has become compromised. In that case just install 1 meg pot like Enzo suggested.
            When the going gets weird... The weird turn pro!

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            • #7
              Fender 3Meg pots are quite common and available..


              I'm trying to find an Ampeg 4 Meg with switch at full clockwise for the trem/after beat function.

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              • #8
                Once again Enzo hits the spot. I have used common 1 Meg aud taper pots in Gibsons and other ancient amps where 2M are original installs, no problem at all. Slug one in there and worry no more.

                What gets me about many old Gibsons & Epiphones, the reverb level is independent of the volume control. For a lark you can dial the dry volume to nothing, and play "all the way in the back of the tunnel."

                drewl, I've never seen a 4 Meg w/ switch like what you need for those blue shower curtain Ampegs. Nor any other pot with the switch activated at full clockwise. You might experiment with a 1 Meg pot with pull switch instead. Lucky for me, I haven't yet run across an Ampeg that needed the 4M, but surely one of these days one will pop up. Tomorrow. Guaranteed. It's 10 minutes to midnight. Murphy will see to it, you know he will....
                This isn't the future I signed up for.

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                • #9
                  Originally posted by rocks66ss View Post
                  ...it seems like 2meg audio taper pots are as rare as hen's teeth. Does anyone know where I can get one?...
                  Rocky Hill
                  Tubesandmore[dot]com has them. $1.60 each. 2M Audio Taper, Alpha, 3/8" bushing.

                  Justin
                  "Wow it's red! That doesn't look like the standard Marshall red. It's more like hooker lipstick/clown nose/poodle pecker red." - Chuck H. -
                  "Of course that means playing **LOUD** , best but useless solution to modern sissy snowflake players." - J.M. Fahey -
                  "All I ever managed to do with that amp was... kill small rodents within a 50 yard radius of my practice building." - Tone Meister -

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                  • #10
                    The one part I always prayed would not break in my 67 Reverberocket 2... Then I sold it.

                    Jusrin
                    "Wow it's red! That doesn't look like the standard Marshall red. It's more like hooker lipstick/clown nose/poodle pecker red." - Chuck H. -
                    "Of course that means playing **LOUD** , best but useless solution to modern sissy snowflake players." - J.M. Fahey -
                    "All I ever managed to do with that amp was... kill small rodents within a 50 yard radius of my practice building." - Tone Meister -

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                    • #11
                      As can see there is a path to the v1 plate to ground through 500pF cap , so maybe big 2M resistor is matter. You can fit one 1M resistor in top of more common 1M pot and then get half of max signal for reverb stage, but think can be recovered in output changing 1M resistor to 470k in mixer output divider. Just my 2cents...

                      and btw. found mostly of 1M audio pots to be into more 800-850k range
                      If Y ou choose to use 1M instead 2M you have to change the 500pF cap as well
                      "If it measures good and sounds bad, it is bad. If it measures bad and sounds good, you are measuring the wrong things."

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                      • #12
                        Originally posted by Leo_Gnardo View Post

                        drewl, I've never seen a 4 Meg w/ switch like what you need for those blue shower curtain Ampegs. Nor any other pot with the switch activated at full clockwise. You might experiment with a 1 Meg pot with pull switch instead. Lucky for me, I haven't yet run across an Ampeg that needed the 4M, but surely one of these days one will pop up. Tomorrow. Guaranteed. It's 10 minutes to midnight. Murphy will see to it, you know he will....
                        Someone had tried a 500K but trem is too weak with that.
                        I was thinking of using a dual couple Meg pot and use one side as the after beat switch.

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                        • #13
                          Originally posted by The Dude View Post
                          You might contact Torres Engineering and see if they still have them. They used to. It doesn't spec taper in the link, but they use them for guitar, so my bet is that it's audio taper. It might be worth a phone call to find out.

                          https://torresengineering.stores.yahoo.net/2megpot.html

                          Edit: Here's the schematic:

                          [ATTACH=CONFIG]55581[/ATTACH]
                          Thank you very much for the link, I appreciate it very much.

                          Rocky

                          Comment


                          • #14
                            Originally posted by Justin Thomas View Post
                            Tubesandmore[dot]com has them. $1.60 each. 2M Audio Taper, Alpha, 3/8" bushing.

                            Justin
                            Thanks for the info, I believe they will be able to help.


                            Rocky

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                            • #15
                              thanks for everyone's help, it's much appreciated.


                              Rocky

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