Loose power tubes

Discussion in 'Amps/Cabs Tech Corner: Amplifier, Cab & Speakers' started by Tone Loco, Nov 11, 2005.

  1. Tone Loco

    Tone Loco Silver Supporting Member

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    I got a new set of tubes and these things are barely hanging in there. I mean I can see them wobble, I wouldn't be surprised if one fell out! The old ones probably were loose too which is why I ended up blowing a fuse...

    But the w/the new ones I'm getting interemittent nasty loud speaker damaging type sounds...

    Any advice on what I can do to get the tubes to seat tightly? There must be something in there that piches the pins but I don't see what it is or how to make it do what its supposed to.
     
  2. rockon1

    rockon1 Member

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    The following is from Torres Engineering...He doesnt mention the lethal voltages that can be stored in a power amp though! Cause Im a chicken I used rubber gloves when I tightened up mine!Perhaps somebody here knows more about how long they hold a charge or if they can be discharged. At any rate this is what he said. From what I understand the stored voltages (even unplugged) can kill!

    "The single power tube glowing red. Obviously it doesn't have any bias, or the tube is bad. Very few people think of this easy repair trick.

    Wait until the red hot tube cools down. Then switch it with another identical tube in the amp. Does the problem go with the tube or stay with the socket?

    If it goes along with the tube, you have a bad tube - if it stays with the tube socket, that is, the other tube glows red in that socket, the socket may have a problem.

    Most likely, the leaves inside the tube socket are not making contact with the tube pins. Very, very common. Various tubes, new and old, have slightly different sized pins.

    Get the amp out of the chassis so you can work on it, unplug everything, and work on the tube sockets. Look down inside and find the thin metal contacts. I use an old jewelers screwdriver (very thin) to bend them inward so they grab the tube pins better. Then clean with a quality cleaner (Caig is our favorite) and plug your tubes back in.

    Check it out - you may have fixed a serious problem very easily."
     
  3. Tone Loco

    Tone Loco Silver Supporting Member

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    Each of the pin holes seems to have two teeny little wires. So the idea is to bend each of the two wires inwards, in each of the holes that takes a pin? I actually tried that... and it seemed like it worked at first. Well actually at first I couldn't get the damn pins into the holes, I guess I bent some of the wires too far, so I had to reverse the process for some of them. But anyhow, after a couple hours of playing I was back to where I started. I hope thats not the only fix.

    As far as discharging the amp I've heard the way to do it is to strum the guitar loud, turn off the amp and keep strumming till you can't hear any sound coming out of the speakers. Not sure its true but it prolly can't hurt. Rubber gloves might not be a bad idea either :eek:
     
  4. Richard Guy

    Richard Guy Member

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    You can discharge the amp buy turning off the power and then put the 'standby' switch to the 'on' position. Another way is to short the '+' side of the electrolytics to ground. Remember to remove the power cord from the wall. I use both ways.
     
  5. rockon1

    rockon1 Member

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    I imagine if you cant tighten up the sockets you would have to replace them.:(
     
  6. Wakarusa

    Wakarusa Member

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    Tightening the retaining pins in the sockets is never a permanent solution (FWIW a dental pick may work better than a jewelers screwdriver). The metal fatigues pretty easily, so once you start bending stuff around it weakens the clips. After a few times the clips won't grip well anymore. After enough times, they break off. The best solution is to replace the sockets.
     

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