Bassman RI troubleshooting

[Enzo]

The thing to do is start a new thread for your amp. This thread has been dead almost a year.

And there is no guarantee at all that whatever was wrong with his will be what is wrong with yours.

Look at the solder on your tube socket pins. Push on the pc board with a wooden stick or something to see if flexing it makes anything happen.

[Bluefinger]

Yes, the Bassman has been on the road for a year now without any troubles. I decided that searching for a single component that causes troubles is useless because on those PCB amp everything is soldered from the back of the board. So I just took it apart and replaced all the resistors and caps on the board and in the can with quality components. I also replaced the thin crappy wires which go to the control board and the tube sockets with solid core cloth covered wire. I also replaced the plasic tube sockets with ceramic ones. It was a rather small financial investment and a lot less time consuming than replacing one thing at a time. This way the crackling has been fixed and the amp is much more reliable than it was before. With the clean lead dress noise was reduced as well.

[MWJB]

"Did you ever find a solution to this problem? I have had the same with my 410 Bassman. It was an intermittent crackling, but now it has advanced into consistent weak, scratchy output."

First stop is to check the 1W Flame Proof resistors at screen grids (470ohms), PI plates (100K & 82K), also check the 100K that feeds the cathode follower. These are the most common parts to fail on a RI Bassman.

If the 470ohm screen grid resistors are the cause it's wisest to mount the new resistors on the tube sockets (not back on the board...or the same thing will happen again later), run a feed wire from the upstream side of the choke connector.