Fender Deville 2x12

Discussion in 'Amps/Cabs Tech Corner: Amplifier, Cab & Speakers' started by ReginaldBisquet, Jan 30, 2012.

  1. Jan 30, 2012 #1
    ReginaldBisquet

    ReginaldBisquet Member

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    Houston
    A friend of mine brought over his dead Fender Deville 2x12. He said the amp no longer powers up... not even the bulb lights up. He loved this amp and wants it repaired, but his budget is $200.

    After doing some trouble shooting, I narrowed the issue down to the thermister (also called an inrush limiter) located at TH-1. I also noticed that two capacitors (C40 and C41) were very wobbly.... like a loose teeth. Other than that, the board looks good. Even still has the original grid resisters which (I am told) burn out quickly.

    Question: anyone out there experience a bad thermister on these amps?

    Also - his master volume knob is busted... it it keeps spinning round and round. Probably from stripped while getting beat up on the road.

    And while I have it open - I was thinking of changing out some caps and resistors as per DIYGuitarist.com's recommendations.

    So here's what I have on the shopping list:

    Watts Tube Audio
    C23 1.5uf --> .022/400v (SOZO)
    C26 0.1uf --> .047uf/630v (Mallory 150)
    C27 same as above
    R12 130k --> 82k/1 watt
    C40 1000uf/35 volt --> same (Sprague)
    C41 1000uf/35 volt --> same (Sprague)
    R61 1 watt/470 ohm --> 3 watt / 470 ohm (metal oxide)
    R62 same as above


    Darren Riley
    R26 Master Volume (Fender Part # 0037600) 100K B (Darren highly recommended NOT installing an audio pot)
    TH1 10 ohm / 4 amp C60-11
    Tube stabilizer foamy thing (he lost his long ago)


    Antique Electronic Supply
    TAD 12AX7 (x3)
    TAD 6L6 WGC (x2)
     
    Last edited: Feb 11, 2012
    ReginaldBisquet, Jan 30, 2012
    ReginaldBisquet, Jan 30, 2012
    #1
  2. Jan 30, 2012 #2
    TweeDLX

    TweeDLX Member

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    Removing and replacing the boards on these amps can be very tricky. It's easy (I know from experience) to break the crappy ribbon connectors that connect them together. Care and caution is advised.
     
    TweeDLX, Jan 30, 2012
    TweeDLX, Jan 30, 2012
    #2
  3. Jan 30, 2012 #3
    DT7

    DT7 Member

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    Keep in view the old addage,"If it isn't broken, don't fix it." If your friend liked the way it sounded, don't go making a bunch of mods to it...or replacing tubes, for that matter. Just fix what's broken.
     
    DT7, Jan 30, 2012
    DT7, Jan 30, 2012
    #3
  4. Jan 30, 2012 #4
    900z1

    900z1 Member

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    +1 also watch out for the orange caps on the daughter board that holds the tubes, they are in the way and can break also. I've had problems with both them and the ribbon connectors
     
    900z1, Jan 30, 2012
    900z1, Jan 30, 2012
    #4
  5. Jan 30, 2012 #5
    ReginaldBisquet

    ReginaldBisquet Member

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    I found out the hard way just how difficult it is to remove this board. But it's out and ready for work.

    The amp came to me with no tubes at all - so he'll need some anyway. And yeah, I am hesitant to make additional changes if he's already happy with the amp. I would really like to switch out R61 and R62 to a slightly higher wattage resistor... just to give the circuit a little more safety.

    That thermister... I'm still curious if anyone has replaced one.
     
    ReginaldBisquet, Jan 30, 2012
    ReginaldBisquet, Jan 30, 2012
    #5
  6. Jan 30, 2012 #6
    jay42

    jay42 Member

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    Replace it with a 20ga jumper if it's bad.
     
    jay42, Jan 30, 2012
    jay42, Jan 30, 2012
    #6
  7. Jan 30, 2012 #7
    ReginaldBisquet

    ReginaldBisquet Member

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    Oh really? Why? Doesn't the thermister provide a useful function with the amp's circuit?
     
    Last edited: Jan 30, 2012
    ReginaldBisquet, Jan 30, 2012
    ReginaldBisquet, Jan 30, 2012
    #7
  8. Jan 31, 2012 #8
    Ronsonic

    Ronsonic Member

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    It does, but nothing serious. It does reduce nuisance fuse blows and makes life a little easier on the power switch.

    On some products bypassing those is standard practice.

    Replace it to do it right, or bypass it to get the thing running.
     
    Ronsonic, Jan 31, 2012
    Ronsonic, Jan 31, 2012
    #8
  9. Feb 14, 2012 #9
    ReginaldBisquet

    ReginaldBisquet Member

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    Okay - all parts installed. Problem fixed! Plus - the amp really comes alive now. I installed a 12AT7 in V1 to bring down the gain a bit as he likes to play loud and somewhat clean.

    Amp sounds incredible. Owner is also very very very happy.
     
    ReginaldBisquet, Feb 14, 2012
    ReginaldBisquet, Feb 14, 2012
    #9

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