bad tube socket?
- Thread starter JMR
- Start date
Fresh_Start
New member
Re: bad tube socket?
Not trying to be a pain - What do you mean by "act microphonic"?
Assuming you mean mechanical noise trigger by the amp's sound, how did you narrow the noise down to a specific socket?
Could be a bad solder joint on the socket, bad connection on one pin, a loose component close by...
First stop - spray some contact cleaner on the tube pins, work a tube in and out a few times, dry off the pins, and fire it up. Second stop - retension the tube socket. Third stop - amp tech.
On second thought, please don't try re-tensioning the tube socket unless you know how to drain the charge from the filter caps. The plate pins are connected to the power rail and could shock you even with the amp un-plugged.
Hope this helps,
Chip
Not trying to be a pain - What do you mean by "act microphonic"?
Assuming you mean mechanical noise trigger by the amp's sound, how did you narrow the noise down to a specific socket?
Could be a bad solder joint on the socket, bad connection on one pin, a loose component close by...
First stop - spray some contact cleaner on the tube pins, work a tube in and out a few times, dry off the pins, and fire it up. Second stop - retension the tube socket. Third stop - amp tech.
On second thought, please don't try re-tensioning the tube socket unless you know how to drain the charge from the filter caps. The plate pins are connected to the power rail and could shock you even with the amp un-plugged.
Hope this helps,
Chip
JMR
New member
Re: bad tube socket?
Hey mang thanks for the reply. Sorry I didnt give enough info at first, heres the whole story:
Last weekend the amp started feeding back badly, with a howling sound. Tapping the tube in V1 makes a ringing sound come through the amp. Since the other guitarist I play with uses the same preamp, I tried it on hers as well, and it does not act the same way.
Some research online suggested to me that this type of symptom is that of a microphonic tube, so I got a new one and replaced it. The new one does the same thing. Switching tubes out from one position to another reveals that whatever tube is in V1 does it.
After discovering this and posting this thread last night, I did some more research today and I think you may be right about the socket needing to be re-tensioned... looking into the socket, I can clearly see that three of the holes are considerably larger than the adjacent ones. (the metal retaining bits, not the holes themselves).
Ill try the contact cleaner thing first. Thanks for the help.
Hey mang thanks for the reply. Sorry I didnt give enough info at first, heres the whole story:
Last weekend the amp started feeding back badly, with a howling sound. Tapping the tube in V1 makes a ringing sound come through the amp. Since the other guitarist I play with uses the same preamp, I tried it on hers as well, and it does not act the same way.
Some research online suggested to me that this type of symptom is that of a microphonic tube, so I got a new one and replaced it. The new one does the same thing. Switching tubes out from one position to another reveals that whatever tube is in V1 does it.
After discovering this and posting this thread last night, I did some more research today and I think you may be right about the socket needing to be re-tensioned... looking into the socket, I can clearly see that three of the holes are considerably larger than the adjacent ones. (the metal retaining bits, not the holes themselves).
Ill try the contact cleaner thing first. Thanks for the help.
JMR
New member
Re: bad tube socket?
OK, today I cleaned the contacts, no luck. Retensioned the connectors, no luck.
I dug around in some usenet posts, and found talk of cracked solder and microphonic caps.
I just fired it up and tapped around on some caps, and sure enough, one right near the input jack makes a very loud thud, accompanied by a bit of ringing when tapped, even lightly. It does this even at low volumes.
Tomorrow I am gonna replace the cap... wish me luck!
OK, today I cleaned the contacts, no luck. Retensioned the connectors, no luck.
I dug around in some usenet posts, and found talk of cracked solder and microphonic caps.
I just fired it up and tapped around on some caps, and sure enough, one right near the input jack makes a very loud thud, accompanied by a bit of ringing when tapped, even lightly. It does this even at low volumes.
Tomorrow I am gonna replace the cap... wish me luck!