no overdrive channel post socket clean

Discussion in 'Amps/Cabs Tech Corner: Amplifier, Cab & Speakers' started by istantodf, May 11, 2015.

  1. istantodf

    istantodf Member

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    Hello,
    i have had an engl screamer 50 combo for nearly 2 years now, in which time it has been well gigged without any problems. But now, i now something's wrong.

    Here's a rundown:

    mid-april: crackling noises, reverb feeding back at around 11 o'clock. Decided that maybe i should clean the tube sockets with contact cleaner. So i did. Cracking is pretty gone, reverb still feeds back and now my overdrive channel has no sound at all unless you run the level and master on full and all get is a weak clean sound coming through.

    Did i royally mess something up while cleaning the pots?
    Also, i rotated and swapped out preamp tubes just in case, but nothing came of it. I have some studio and stage gigs coming up in a month. Starting to stress.

    Thanks for reading
     
    Last edited: May 11, 2015
  2. axpro

    axpro Member

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    Did you blow out any residue after cleaning the sockets? for that matter did you discharge the caps beforehand? Contact cleaner is okay stuff, but you have to make sure you get the excess out before you add power, and that you discharge any power FIRST. excess cleaner is just a liquid sitting on solder traces and components, add power and it would be easy to short something.
     
  3. istantodf

    istantodf Member

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    Thanks for replying.

    It appears that i forgot to discharge the caps and now feel like a dummy for doing so. I applied the cleaner, worked the tube in and out then let it sit to dry for about 15 mins.
    how bad have i screwed up? Is this even fixable without costing an arm and a leg?

    Sorry for the questions, but thanks for the help.
     
  4. DaveKS

    DaveKS Member

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    Contact cleaner should evaporate completely within 30min of use, unless you used contact cleaner with lube. What did you use? Contact cleaner should be sprayed on pins of tube and quickly inserted in socket a few times.

    There is a chance also that you've messed up (bent pin grabbers) in the socket. Your statement that only on OD chan is effected? Does that mean clean channel works properly?

    Tube layout...... From some forum
    clean, lo gain V1A - V2B - tone stack etc
    clean, hi gain V1A - V2A (through R20, R6, R17, R58) - V2B - tone stack etc
    lead, lo gain V1A - V1B - V2B - tone stack etc
    lead, hi gain V1A - V1B - V2A - V2B - tone stack etc

    So if lead chan is one with problem, v1b is culprit it would seem, trying a new tube and inspecting that v1 socket closely would be 1st things to look at.

    Also what are preamp tubes? JJ by chance? I have seen this a few times, JJ can come with extremely undersized tube pins, so small in fact that unless tube socket retainers are perfect the pin won't make good contact. Easy fix by using a tube that's got proper sized pins.
     
  5. istantodf

    istantodf Member

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    Thanks again.

    Contact cleaner was non-lube. sprayed in socket because someone said i should and inserted tube a few times. The tubes were stock, then i tried some old GTs i had laying around. Nothing worked so i figure it might be damage on the socket/pingrabbers as you said.

    Only clean channel works. Overdrive is dead silent until turned up level and master wise until about 7 oclock
     
  6. istantodf

    istantodf Member

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    Update... got it fixed by a tech and then retubed and biased it myself with some jj tubes from eurotubes.com. Sounds fantasmagorical....
     
  7. Blue Strat

    Blue Strat Member

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    What did the problem end up being?
     
  8. schmidlin

    schmidlin Member

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    He forgot to employ a tech.
     
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  9. istantodf

    istantodf Member

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    Broken v2 tube socket.

    I usually diy most things as techs here aren't that reliable. But this guy did a good job.

    Thanks for the humour.
     
  10. RussB

    RussB low rent hobbyist Silver Supporting Member

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    I think it's weird that you bought tubes from EuroBob when you have a most excellent tube retailer in Ankara
     
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  11. istantodf

    istantodf Member

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    Well aware of koray in ankara. Wanted to try out some jjs and am so far wuite pleaed with them. Have never gone down the nos route, but might do so this year.
     
  12. RussB

    RussB low rent hobbyist Silver Supporting Member

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    I have nothing against EuroBob and you're free to buy from whomever you wish. Still, with JJ's being made in the Slovak Republic, it seems there would be retailers nearby?

    Those Zaerix/Ultron labeled Russian tubes are very good. They are more commonly called 6p14p, 6p14p-k, 6p14p-ev
     
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  13. istantodf

    istantodf Member

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  14. RussB

    RussB low rent hobbyist Silver Supporting Member

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    It's cool to converse with folks from around the world to get different perspectives. Thanks!
     
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  15. istantodf

    istantodf Member

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    Likewise
     

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