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re-tubed, now pops,clicks, and power loss.

Discussion in 'Amps and Cabs [BG]' started by tbird46553, Jan 15, 2012.


  1. tbird46553

    tbird46553 Supporting Member

    Jan 7, 2012
    North Central IN
    Put a new set of JJ tubes in my early/mid 70s V4B. It had power drops and tonal variations, so I thought new tubes would help. I'm no tech, so..... now it pops, clicks, AND still has original issues. Any help anyone?
     
  2. Unless you're comfortable working with high voltages (500-600 volts), take it to a qualified tech. It could be corroded tube contacts (which can be cleaned with Caig DeOxit), plate resistors breaking down or arcing contacts in other parts of the circuit or any number of other things.
     
  3. christw

    christw Get low!

    May 11, 2008
    Dayton OH
    I want to be Tesla (tinkerer at Dayton Amp Co)
    I agree with timmus, it sounds like tech time. There are only a few things that I would be comfortable troubleshooting in an amp that size and you've already checked one of them.
     
  4. +100000000 for tech
     
  5. Could be something basic maintenance could take care of or somewhere you should not go yourself. Save the time and money and take it to a good tech. They could have already saved you the cost of the tubes? :)
     
  6. nouroog

    nouroog

    Jan 14, 2010
    Lyon, France
    +1
    And please post the result of the tech trip.
    Every bit of shared experience is valuable
    :)
     
  7. RickenBoogie

    RickenBoogie

    Jul 22, 2007
    Dallas, TX
    Yes, you need an amp tech. It's always a good idea to have a reliable tech anyway. time to find one now.
     
  8. Some simple things you can do before taking it to a tech is clean the inputs (speaker and instrument), the pots and the tube sockets by spraying some deoxit. Try putting a different 12AX7 in v1 and v2. I don't know if you only swapped out the power tubes. Another tube slot that will cause those noises and power loss is the Phase Inverter. That's a 12AU7. I had a blackplate 12BH7 in my v4 with great success/tone. Good luck.
     
  9. christw

    christw Get low!

    May 11, 2008
    Dayton OH
    I want to be Tesla (tinkerer at Dayton Amp Co)
    I had assume the OP already tried switching the phase inverter but the symptoms sound like they could be right. I lost one, a vintage RCA 12AX7, a month or two ago in a Marshall.
     
  10. nouroog

    nouroog

    Jan 14, 2010
    Lyon, France
    I had a similar experience these past months with my silverface bassman, but the symptoms were intermittent.
    I had volume loss, distorted sound and overheating powertubes with blue glow.
    After changing the power tubes without solving the problem, it turned out the problem was coming from the PI, in my case a RCA 12AT7.
    Changing it seems to have solved the problem, although time will tell.
     
  11. will33

    will33

    May 22, 2006
    austin,tx
    +1 to doing a simple cleaning. That much you can do yourself. Stay away from voltage. Just pots, jacks and switches and tube sockets.. Then put the old tubes back in it. If it's still acting up, take it to a tech. If it turns out it needs tubes, you already have them. If not, save them for someday when it does. Your new tubes would've likely needed the bias adjusted compared to the old ones. That may be one reason just plugging them in made it worse. Dirty sockets, corroded contacts, etc. may also be a problem.
     
  12. tbird46553

    tbird46553 Supporting Member

    Jan 7, 2012
    North Central IN
    I thought a tech was probably in order. So who knows a good one in northern Indiana?
     
  13. BogeyBass

    BogeyBass

    Sep 14, 2010
    Did you just replace the power tubes, what type did yah use? not brand, model # like 7027 6550 etc

    poping and clicks could be bad pre amp tubes, power loss could be bad caps and bias circuit.

    Pre tubes are easy, bad caps and bias = Good tech can replace those for you
     
  14. tbird46553

    tbird46553 Supporting Member

    Jan 7, 2012
    North Central IN
    Thanks for all the help. I replaced all the tubes w/a set from Fliptops. All JJ except for a NOS RCA 6K11. Powers are 7027a's.
    Still hope somebody knows a good tube tech in northern IN lower MI?
     

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