'62 Fender Tremolux questions with mods questions

Discussion in 'Glowing Bottle Tube Amp Forum' started by 1954 Esquire, Jan 27, 2019.

  1. 1954 Esquire

    1954 Esquire TDPRI Member

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    Greeting, I have a '62 Tremolux head that has been modified and need some help in figuring out what they are and there functions. The ones that are obvious is the tremolo jack has be replaced with a pot. and it has been converted to EL34 tubes. Inside the chassis, and only accessible by removing the chassis is a mini pot wired to the intensity control for the tremolo. Hope the pictures help out. Any information would be greatly appreciated. IMG_1851.jpg IMG_1852.jpg IMG_1851.jpg IMG_1852.jpg IMG_1854.jpg IMG_1870.jpg IMG_1865 (1).jpg IMG_1854.jpg IMG_1870.jpg IMG_1865 (1).jpg
     
  2. Snfoilhat

    Snfoilhat Tele-Afflicted

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    The placement of the mini pot is typical for adjustable fixed bias. The pot in the trem foot switch hole being dual-gang and having what looks like shielded cables makes me think master volume.

    But you could help everyone help you if you gave some indication of what the controls do as you manipulate them (at least in the case of the external control).

    Confirming exactly what these are (for example, precisely which style of master volume if that's the case) would take some additional effort on your part making drawings or writing out of the connections and noting the component values. That Tremolux looks very cool. Good luck
     
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  3. archetype

    archetype Fiend of Leo's

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    If you're a do-it-yourselfer, start with the tube chart inside the cabinet and figure out what circuit the chart claims it to be. The charts are frequently rong, but it's a start. The best way to proceed is to brew a pot of coffee and slowly compare the head's layout to the schematic. After determining what circuit you really have, you can sketch out the modifications to understand them. Here's some info and schematics...

    http://ampwares.com/amplifiers/fender-blonde-tremolux/
     
  4. flyswatter

    flyswatter Friend of Leo's

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    The dual shielded cables from the caps at the end of the board -- phase inverter -- to the rear pot indicate PPIMV master volume. That mini pot definitely looks like bias adjustment, as Snfoilhat already indicated. There are other new-looking wires too (lime green?) but I can't see from the pictures where they go. In photos 3&4 I'm also seeing what looks like new wire on the output transformer primaries that suggest the OT might have been replaced. You can tell fairly easily by looking at the OT itself... whether it's new and shiny and aftermarket vs. a more weathered-looking original.
     
  5. 1954 Esquire

    1954 Esquire TDPRI Member

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    Thanks for the replies, I put all the tubes in and found I was missing the GZ34 tube. I have installed a new one and it does not warm up like all the other tubes. Before I received the new tube I powered up the head and it played without it (GZ34) I only played it for about 5 minutes. It is low volume and muddy sounding. Could it be that this was modified to work without the GZ34 or is that even possible. The pot installed in the tremolo plug in is a master volume, found this out after the fact.
     
  6. milocj

    milocj Friend of Leo's Ad Free Member

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    It's possible that somebody converted the amp to have a solid state rectifier, and also disconnected the heater wires to the rectifier socket at the same time. It only takes wiring in a couple of diodes across the rectifier socket to make it work without the tube.
     
  7. 1954 Esquire

    1954 Esquire TDPRI Member

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    Removed the chassis from the cabinet and see two diodes wired across the rectifier socket. If I remove the diodes would that enable the socket to use the tube?
     
  8. David Barnett

    David Barnett Doctor of Teleocity

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    EL34s draw a lot more heater current than 6L6s (1.5A per tube vs 0.9A), if this amp still has its original power transformer then it's unlikely to be up to the task. I'd stick 6L6s back in there before firing it up again.
     
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  9. 1954 Esquire

    1954 Esquire TDPRI Member

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    Thanks for the information, have a pair of 6L6’s I will put in it.
     
  10. milocj

    milocj Friend of Leo's Ad Free Member

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    Since the rectifier isn't heating up you need to see if the two (usually) yellow 5v heater wires from the power transformer are hooked to that socket and to the correct pins.

    The diodes were installed and the heaters (if disconnected) were most likely done to allow for the extra current draw of those EL34s.
     
  11. milocj

    milocj Friend of Leo's Ad Free Member

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    .
     
  12. 1954 Esquire

    1954 Esquire TDPRI Member

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    Well I removed the diodes and with the help of a schematic and my trusty soldering iron I hooked back up the one yellow wire from the power transformer that had been removed. The rectifier tube now powers up. Now I am trying to figure out how to get the tremolo circuit back up.
     
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  13. BobbyZ

    BobbyZ Doctor of Teleocity

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    Have you changed out all the electrolytic caps yet?
    And I do mean ALL of them.
    I see old ones in there and a weak bypass cap can make a trem not work.
    Other things can too but do the Ecaps first to eliminate that possibility.
     
  14. archetype

    archetype Fiend of Leo's

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    What @BobbyZ said. Bad electrolytic caps can smoke your PT if one of them shorts. Turn it off and don't power it until those are replaced. No joke.
     
  15. 1954 Esquire

    1954 Esquire TDPRI Member

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    Thanks for all the great information, the amp work is on hold until I can find someone to service it for me. I can do minor repairs but would prefer to have a experienced person work on it.
     
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