1960 Center Volume 5G12 Brown Concert

Discussion in 'Amp Central Station' started by rw4951, Oct 7, 2018.

  1. Bulldoggio

    Bulldoggio TDPRI Member

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    Wonderful! I have #528, with identical specs. What a beast!
     
  2. rw4951

    rw4951 TDPRI Member

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    At some point, the amp had the filter caps replaced with cheap IC's:

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    Pulled those out and cleaned up the board a little:

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    Checked the 1W carbon comps and they were within spec, so I left them for now. Replaced filter caps with 20uf 500V Sprague Atoms:

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    After I removed the cap pan, I noticed the stamped JC date code which indicates a March 1960 build date. Several of the pots dated to the 8th week of 1960. Tube chart indicates production run #2.

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    Next will be new Spragues for the cathode bypass caps and bias caps on the main board and bias/rectifier board.

    Freshly re-coned pair of P10Q's arriving next week from Weber...
     
    rdjones and Axis29 like this.
  3. keithb7

    keithb7 Friend of Leo's

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    Sweet booger flicker, that's a find! A great score there on a rare amp. #45249 is indeed the same OT in my 1960 Tweed Bassman 5F6A. I felt a rush and ran to check my Bassman. Same choke too. I checked. ;)

    The gut shots are coming, right?

    https://goo.gl/images/5MQDJh
     
    Mr Ridesglide and Axis29 like this.
  4. gridlock

    gridlock Friend of Leo's

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    That amp is so nice.
    Jealous. Congrats.
     
  5. David Barnett

    David Barnett Doctor of Teleocity

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    I'll just say it - "center volume" brownface Fenders are the most desirable amplifiers ever made.
     
    rw4951 likes this.
  6. rw4951

    rw4951 TDPRI Member

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    This one had very nice innards. The main circuit board was remarkably intact, save for the Aston MiniMite electrolytic caps. Mostly yellow Astrons with a few blue Moulded coupling caps. Not sure if the blues are original or not. Will have to due further testing to check for DC leakage on these after I get it brought back on-line.

    Resistors all measured within spec. Might replace a couple that have drifted up a bit.

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    Since the previously replaced electrolytic caps were of unknown age (and there were a couple of values that weren't original spec), they were pulled and replaced with new Sprague Atoms of the correct value:

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    Will also be adding a bracket mounted bias trim pot. Next step will be power-up using a light bulb limiter and a Variac..
     
  7. tele_savales

    tele_savales Tele-Meister

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    my brother got one just like it when I was in high school. SCREAMING loud.
     
  8. dannyh

    dannyh Tele-Afflicted

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    For what it's worth, my '61 Deluxe has a mix of (mostly) yellow Astrons with a few blue molded caps. My 62 Super is all blue molded caps, except for one yellow Astron. As I understand it, this time period was when the yellows were phased out for the blues, but Leo wouldn't waste anything, so your blue caps may be original.
     
  9. ozcal

    ozcal Tele-Holic

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    wow... very cool...

    rare... rare as rocking horse sh1t i d imagine...
     
  10. rw4951

    rw4951 TDPRI Member

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    Here's an update. I decided to use the ground switch hole for the bias trim pot. Didn't want to pull the chassis every time I want roll a set of power tubes through, and we sure are going to drill any holes! Used a little tag strip mounted on the PT stud to connect the old/new bias wires Also installed a new grounded power cord.

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    A few more gut shots:

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    The amp came with (2) P10R's in excellent shape, and (2) P10Q's that had been reconed. Since one of the Q's was making noise, I sent the pair to Weber for a vintage spec recone. Here they are mounted in the cab in an X-pattern:

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    Made a new pigtail in the correct gauge cloth wire that goes from the junction to the speaker. Used a new RCA plug to be safe.

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    Brought the amp up on a variac and all voltages were within spec. The trem doesn't seem to come alive until the speed comes up to 4-5. Maybe one or more of the Astrons in the trem circuit are weak/leaking DC? The noise floor is higher than I'm willing to live with, so I need to do a bit more troubleshooting there.

    Overall, the amp sounds great and really gives up the goods about 7-8 on the volume. I ran it through a Power Station so I could play it in the sweet spot without losing any more of my hearing.
     
    David Barnett and theprofessor like this.
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