[PROJECT] Fender Twin

Discussion in 'The Squawk Box' started by Kuroyama, Jul 15, 2009.

  1. Kuroyama

    Kuroyama V.I.P. Member

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  2. Cygnus X1

    Cygnus X1 Senior Member

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    Sorry, I lost track.
    OK, you're in for a ride.

    Zero voltage while unplugged for a while is normal-the caps usually bleed down in a few hours tops. Sometimes within seconds, depends on the bleeder resistors. Don't get complacent though.
    Those caps will be first to go-the gray electrolytics and that yellow one most of all.
    Be careful not to pull the traces when you desolder/solder.

    I don't have the time right now-gotta run, but research whether it used leadless solder or not.
    You can't mix one with the other.

    I've seen worse corrosion.
    Look very carefully at those little black diodes to make sure they haven't cracked open.
    Do the same with all of the resistors. Use a magnifying glass to inspect them.

    That power transformer ought to be ok-again I've seen worse.
    Do not try to remove that surface rust.
    Just leave it alone for now.
     
  3. LPSGME

    LPSGME Senior Member

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    What model Twin is this?
    I'm puzzled by all the tube sockets.
    Does it have some sort of tube overdrive circuitry?

    It looks like there are 2 tubes to the left of the 4 power tubes, and 2 tubes to the left of 2 input tubes.

    That would be correct (6 small tubes) for a vintage circuit design. But then what are the boards with the IC's shown on the left side? I assumed they are solid state tremelo and reverb circuits - which would imply the other tubes are extra pre-amps overdrive circuits.

    Are there resistor/capacitor components under that long circuit board that appears to be attached to the pots? If they are, what a tech nightmare that is i.e. having the components hidden on the underside of a board.

    If that were mine (and especially if those are extra overdrive tubes) I'd find some way to 'dumble-ize' it by rewiring the circuit with the needed part values and configuration. You can find some dumble schematics on thegearpage.net

    If those are extra overdrive tubes you could then have a clean twin channel and a basic 'dumble' channel, and could just switch between the two.
     
  4. SatelliteAmps

    SatelliteAmps Senior Member

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    It would be cheaper and easier to just make a clone of a dumble than to try and make that Twin into one.
     
  5. Splattle101

    Splattle101 V.I.P. Member

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    I think he just wants to make it work. He bought it really cheap. I don't think he set out to clone anything.
     
  6. Cygnus X1

    Cygnus X1 Senior Member

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    I believe it is an "Evil Twin", not a bad amp in its own.
    A fun way to learn about amps, but I wouldn't throw too much money at it.
     
  7. Kuroyama

    Kuroyama V.I.P. Member

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    Hey Cyg

    Going for a ride is right!! Train ride to Akihabara!!! Thats a lotta caps to pull/replace. Thatll be a lot of shopping before I start.... though my reading tells me that a full cap job is a good thing. I just dont understand what you saw as faulty in the big gray filter caps. The yellow cap, sure, he looks kinda greasy and sweaty.

    1) But what did you see that makes you think the big gray ones need changing? Was it the voltage values I pulled down?

    2) what are those gray boxy things?

    3) I dont know about lead free solder... I bought silver solder as its advertised as being better for audio work. Though if the two types (whatever the amp has now, vs what I bought) arent compatible, then thats 3 dollars I can let go of. I guess a letter to Fender is in order to get the solder type right.

    4) ah yeah!! thanks for reminding me. I gotta get a big honkin ant killing magnifying lens for inspection.
     
  8. SatelliteAmps

    SatelliteAmps Senior Member

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    My guesses:

    1) Time, age, and condition of other parts.

    2) Which grey boxy things? The cement ones are big resistors, the small plastic ones are capacitors.

    3) It did not use lead-free solder. Very few people did at that time (it did have a surge of popularity because it was a requirement for export, but that is changing once again. It only became a requirement within the last 5 years or so.) Silver solder can be used, as long as it is for electric work, not jewelry work.
     

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