Re-wiring reverb tank in mid 1960's Gibson Guitar Amp

Discussion in 'Technical Repair' started by tireguy37, Sep 17, 2016.

  1. tireguy37

    Thread Starter New Member

    Sep 17, 2016
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    Hello, my first post here. Thanks to anyone who's willing to take the time to help.

    I recently purchased a used mid 60's Gibson Explorer amp GA-15RVT. One of the previous owners for some reason removed the amp's reverb tank so my goal is to install a new reverb tank and get the reverb working again.

    I purchased a new reverb tank from Frank Fendly at www.studiosoundelectronics.com (he's a very nice guy BTW) so I have the correct reverb tank for the amp but I need help deciding how to solder this correctly.

    I have attached the schematic for the amp as well as interior pics. According to Frank at www.studiosoundelectronics.com, what i need to do is solder in a new cable at C11 and then plug that into the reverb tank with an RCA. The problem is that I don't know how to read schematics. Can anyone verify this and or tell me where C11 is?

    Thanks,

    Daniel
     
  2. R!f@@

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    Welcome to AAC

    C11.png
     
  3. R!f@@

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    I cannot make out the caps from the picture as the PCB part labels cannot be seen.

    Reverb has 3 connections
    Ground, Input and Output.
    RCA connectors & properly shielded audio cables are necessary.
    Do you have the proper cables ?
     
  4. tireguy37

    Thread Starter New Member

    Sep 17, 2016
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    Hi, yes. I see that on the schematic. I mentioned on my post that unfortunately I cannot read schematics so I'm a bit stuck. If you look at the interior pic of the amp, can you tell me where I need to solder the wire in?
     
  5. R!f@@

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    I edited post #3

    Can you point to C11 labelled on the PCB ?
     
  6. tireguy37

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    Sep 17, 2016
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    Thanks for the response. Yes, I can solder and I have some cables. As far as i know, the ground should still be there because a reverb unit was previously installed in this amp. The input is what runs from the amp to the reverb unit (this is the cable I need to install). As far as the output, that part is easy as it's just an RCA cable that runs out of the reverb tank and into the amp (no soldering required, just need to plug in, connectors already there).
     
  7. tireguy37

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    Sep 17, 2016
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    Yes, I see that the PCB has numbers listed. Can you verify that C11 is where I need to solder wire to run input RCA into reverb tank? Can you mark on the image and post where this is exactly?
     
  8. R!f@@

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    You need to see the PCB and find out the location of C11 and C13 and R26(not clear).
    Find the part from PCB labeling.

    Rifaa_C.png
    I am a bit new to Valves but from the look of the diag. I assumed the IN and OUT. GND is correct. But reverb will work even if reversed I believe.

    {ed} Made a mistake while cropping the diag.. Sorry. But I believe you can see the soldering points

    Moderators note: please cut away unneeded white space
    Me to Mod note : Thanks Mod.
     
    Last edited: Sep 17, 2016
  9. tireguy37

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    Sep 17, 2016
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    Here's a better pic of the PCB.
     
  10. R!f@@

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    You know that no one can see the numbering under the components from a picture.
    It is upto you to find them
     
  11. bertus

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    Apr 5, 2008
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    Hello,

    @R!f@@ is right.

    ga15rvt_reverb.png

    The output needs to be connected with a shielded cable to avoid hum.

    Bertus
     
    R!f@@ likes this.
  12. R!f@@

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    ThnX Bertus for the confirmation.
     
  13. tireguy37

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    Sep 17, 2016
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    output and ground are already connected

    Need to install input wire from C11 to the reverb tank. Please see attached pic. My best guess is to solder in a wire at this joint and then run that to the input of the reverb tank.
     
  14. R!f@@

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    If that point is same as the point marked on the image shown that you are OK.
     
  15. tireguy37

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    Sep 17, 2016
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    R!f@@, Bertus,
    Thanks for the help. Hopefully I can get it to work :)
     
  16. Alec_t

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    Sep 17, 2013
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    If C11 is supposed to be 10uF I can see nothing on that tag board which corresponds. One end of C11 should share a connection with R22 and R23 (orange/orange/red and brown/black/orange, respectively).
     
  17. tireguy37

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    Sep 17, 2016
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    Good point. I'm going to look see if I can find a 10uF cap on the PCB. Thanks.
     
  18. bertus

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    Hello,

    Here I found a bit more sharp version of the schematic:

    GA15RVT_schematic.png
    It also shows the position of the tubes on the chassis.
    Look for V3 pin 8 and follow the resistor R22 3k3 to the connection point with R21 and R23.

    Bertus
     
  19. tireguy37

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    Sep 17, 2016
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    Wow that is really helpful. Thank you.
     
  20. KL7AJ

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    Nov 4, 2008
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    You shouldn't have to solder anything...there's usually a couple of RCA jacks on the top of the chassis for the in and out. Just be sure you connect the LOW IMPEDANCE end of the tank to the driver amp, and the high impedance end to the subsequent amplifier stage.
     
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