Tube Amps / Music Electronics
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|previous: Jeff Lynch I just finished my 5e3 project and ... -- 8/18/2003 12:50 PM|
|8/19/2003 1:19 PM|
|Jeff Lynch||Re: Crackling intermittently on Mission 5e3|
The problem has been found. Here is what happened. I tried replacing a known good tube for each of the preamp tubes. The problem persisted. I pulled each preamp tube one at a time then turned the amp on. When I got to V2 (12ax7) the crackling stopped. So, with V2 out of the circuit, no crackling. By the way, when I tapped on the chassis with a plastic prod, I got all sorts of strange sounds, even a radio station at one time. That made me think of a spark gap which was an old way of receiving am radio (right Bruce?). A spark gap meant a bad solder joint. One of the suggestions was to touch up solder joints.
I focused on V2 since it was the one that quieted the amp when it was pulled. I re-soldered all of the pins on the tube socket then put the tubes back in and fired it up . . . no crackling! No am radio, no obnoxious noises. Excellent!
I think the problem was the jumper that I used between two adjacent pins on the socket. I found it very difficult to solder a jumper because when I soldered one end it made the jumper hot enough to melt the other end and it would fall off. Any suggestions?
So the conclusion of this crackling problem was a bad solder joint. I learned a bit about troubleshooting; substituting known good tubes, pulling tubes to isolate the problem. Even the AM radio spark gap clue! Good luck to the others who are searching for their answer. Jeff
|Aaron try using a heat sink clamp on the ... -- 8/19/2003 2:01 PM|
Novetti Congratulations man!... -- 8/19/2003 3:36 PM