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Updates on 81 Pro Reverb problems

Discussion in 'Amp Tech Center' started by Axer57, Sep 28, 2017.

  1. Axer57

    Axer57 Tele-Meister

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    I pulled each preamp tube 1 at a time and tried it. It's still there to some degree with all. When I touch V2 though it's completely gone . It's the same even with no instrument or cable plugged in. Guess I need to check connections and re solder V1 , V2 , and V3.
     
  2. corliss1

    corliss1 Friend of Leo's Platinum Supporter

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    So you said it goes away when you touch the heater wire - do you mean touching the ping with something metal, or just touching the wire with a finger or what?

    Reflow the heater connections there to see if that does anything.
     
  3. Axer57

    Axer57 Tele-Meister

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    It was the heater wires. I reflowed all of them from the PI tube to V1 and the hum is gone. guess I need to slow down sometimes and take each connection 1 at a time and ensure that it's a good connection.
    Impatience has always been a big problem of mine.
     
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  4. D'tar

    D'tar Friend of Leo's

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    If I were to replace all those sockets I would be sure to wire the preamp tube heaters in phase with each other..... V1 p4/5 to v2 p4/5, v1p9 to v2p9... Etc...

    Not saying this is your issue, just sayin:)

    I have seen them not like this and still quiet. From the pictures there is plenty of oportunity for lead dress induced noise. Some time with a chopstic may be beneficial.
     
  5. corliss1

    corliss1 Friend of Leo's Platinum Supporter

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    Yay! Glad it was an easy fix!
     
  6. D'tar

    D'tar Friend of Leo's

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    Ahh....

    Glad you got it....

    Every connection counts right!
     
  7. Axer57

    Axer57 Tele-Meister

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    I do have all the heater wires wired exactly as you described D'tar.
    there was just so much wrong with this amp when we started I guess I got in too big of a hurry. This is one case where I should sweat the little things...lol
    This is the first time I've ever gone this deep in an amp. I have replaced parts and tested many times but never with so much to test and replace at one time. I have learned a ton of good things on this one .
     
  8. corliss1

    corliss1 Friend of Leo's Platinum Supporter

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    And THAT is the best part of it all - you learned something. Sure, the amp sounds great, but *you* did it and made it happen.

    Now the next amp where you have issues you can knock it out in a couple hours :D
     
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  9. Axer57

    Axer57 Tele-Meister

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    I should have come here first 11 months ago with the original problem. I love the fact that it's Blackfaced but the tech is probably out quite a bit money for the parts.
    I'm just glad it's working right now.
     
  10. Axer57

    Axer57 Tele-Meister

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    I've noticed , since I removed the braided covering from the 2 input and 2 volume pot wires. If I touch them it produces alot of hum. Any recomendations for better wire at these spots?
     
  11. corliss1

    corliss1 Friend of Leo's Platinum Supporter

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    Nah, that's pretty normal, unless you plan to be touching wires in the amp while playing.
     
  12. Axer57

    Axer57 Tele-Meister

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    LOL...in my younger days I did some dumb things " just to see what would happen" . Not anymore. It cost me a Fender Princeton...
     
  13. D'tar

    D'tar Friend of Leo's

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    I agree, not necessary....

    If you must... RG174
     
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  14. Axer57

    Axer57 Tele-Meister

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    I replaced the input wires with some good wire and put it all back together. Played on it off and on all all day yesterday. It sounds great and idles very smoothly . Thank you to everyone. I couldn't have done it with out you.
     
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  15. Axer57

    Axer57 Tele-Meister

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    Well I thought I was done , but I do have another question. When I turn the volume on either channel. I get nothing until I reach 2 1/2 on the pot. Then I get a weak muffled sound as I reach 3 on the pot it comes on sounding great but at club level. I have read that this is because the original BF pots were 30% and the new ones are 10%. The only 1MA 30% pots I have found online are from mouser , they are Alpha[Taiwan] . Would these pots even out the volume or is this just another wild goose chase.
     
  16. justin.ramsey

    justin.ramsey Tele-Holic

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    Measure the resistance of the pot as you turn up the volume to see if it's working appropriately
     
  17. Axer57

    Axer57 Tele-Meister

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    I put all new CTS pots in the amp. I tested them all before installing them.
     
  18. robrob

    robrob Poster Extraordinaire Ad Free Member

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    What you describe shouldn't be caused by good 10% pots.
     
  19. corliss1

    corliss1 Friend of Leo's Platinum Supporter

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    can someone enlighten me on what the pot percentage means? this is a term I haven't heard
     
  20. robrob

    robrob Poster Extraordinaire Ad Free Member

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    I believe it's the % of total pot resistance at 50% throw. 10% would be more logarithmic than a 30%.
     
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