ampage
Tube Amps / Music Electronics
For current discussions, please visit Music Electronics Forum.

ampage archive

Vintage threads from the first ten years

Search for:  Mode:  
previous: Jeff Lynch I just finished my 5e3 project and ... -- 8/18/2003 12:50 PM view thread

Re: Crackling intermittently on Mission 5e3

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

 
Replies:
Aaron try using a heat sink clamp on the ... -- 8/19/2003 2:01 PM
Novetti Congratulations man!... -- 8/19/2003 3:36 PM