Block letter 5150 major mechanical/cosmetic overhall

Discussion in 'Gear & Equipment' started by Frankb7stringer, Jan 26, 2015.

  1. Frankb7stringer

    Frankb7stringer SS.org Regular

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    Hey guys. After a really intense period of time with my bands there's a small window of relaxation to work on my stuff. I recently received a block letter that's been rode hard and put up wet for the last 10-15 years at least. It's in bad shape but it still manages to put out some amazing stuff (kinda like Bruce Willis), so I'm going to be turning this amp into a project.
    [​IMG]
    The tubes will obviously need to be replaced as they sound fairly mushy and tired. I'm thinking Mullard v1 tung sol in the rest of the preamp spots and power tube spots. The Mullard would just be for clean headroom so if that won't work someone let me know.

    Now comes the juicy stuff. All of the pots in the amp need to be replaced some are broken on the posts some don't turn smooth or the effect they change doesn't change properly with the turn.

    There's an issue that's stumping me atm. There's a volume drop out that happens randomly and goes away when you smack the top of the amp. The tone doesn't change a whole lot it just drops out majorly. Would this be a preamp tube issue or an issue with the fx loop jacks?

    Once the mechanical issues are fixed I plan on recovering the head cabinet with new tolex to match a different color scheme on the knobs and maybe the logo. Any suggestions would be greatly appreciated.
     
  2. Frankb7stringer

    Frankb7stringer SS.org Regular

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  3. USMarine75

    USMarine75 Doc McStuffins Contributor

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    Or just spend the money and have it professionally modded... :)

    If you do it yourself... I went with a 12AT7 in the PI to make the pregain more usable from 5-10 instead of just sounding dimed at 7 like most 5150's do. Have JJ ECC83S gold in the V1,V3,V4 and an EHX gold in the V2 to eliminate any microphonics, but still have crushing distortion. You can replace the transformer and choke (Mercury Magnetics -- The Guitar Amp Transformer Company) as well.

    Not sure about the volume drop, but I suspect replacing the tubes and pots will alleviate it. :scratch:
     
  4. Frankb7stringer

    Frankb7stringer SS.org Regular

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    I'm guessing v5 is the phase inverter? I've always done my own stuff to amps and it's not part of my show rig yet so it doesn't need to be rushed. I would rather learn what I can for doing it on my own. What would changing the transformer and choke do for the tone?
     
  5. USMarine75

    USMarine75 Doc McStuffins Contributor

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    The choke is just another term for an inductor located after the power supply that filter's unwanted leftover noise from the AC signal when it gets converted to DC. Supposedly this allows for clean DC to power the amp elements.

    As for the purpose of a transformer and why you might change it --> Why and How to Replace Your Amplifier
     
  6. Frankb7stringer

    Frankb7stringer SS.org Regular

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    It definetly sounds like something i could do. I just want to get it working properly again first.

    I was thinking navy tolex with white corners and a white grill over the logo. Possibly knobs to match the tolex if i can find them.

    Any tube recommendations for this head?
     
  7. Albionic

    Albionic First of the magi

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    Volume drop is likely to be power tube try tapping each tube with a pencil see if you can get volume drop to occur
     

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