Rm100 Unceremoniously Dies

[Tube Head]

Well I've been playing the amp for 3 hours today and have had no problems with the transformers heating up.

I still looking for more trouble shooting advice. Maybe this problem is too difficult for me to fix. I can solder well but have a limited knowledge of electronics. I dont want this amp to quit anymore at gigs.

 

[Soulinsane]

Thats good then. At least its nothing really expensive. It is possible that the tube socket or something else could be bad but I'm thinking it might just have been the tube.

I know its freaky that it happened in the same place twice already but chances are it was just the tubes you put in that location. They are unreliable by nature. If it happens again then you know for sure that something is actually destroying the tube in that location. Replicating the problem seems hard to do. It is going to take someone a little time to inspect and test parts to exercise the gremlins if thats the case.

One thing it could be is the 1 ohm bias test resistor for that tube location has drifted out of spec and is causing you to bias the tube out of spec. That's one thing that will cause a tube to fail fast.

 

[Tube Head]

I sat down with the RM100 and my little tube collection and found that tube socket 3 is definitly malfunctioning. No matter what adjustment, it gives me a 1 on my multimeter. I checked the fuse and it is fine. All the tubes I have still work great in the outside slots.

 

[Soulinsane]

I sat down with the RM100 and my little tube collection and found that tube socket 3 is definitely malfunctioning. No matter what adjustment, it gives me a 1 on my multimeter. I checked the fuse and it is fine. All the tubes I have still work great in the outside slots.

Its definitely something with the bias resistor for that socket if not more. There is another member here that had the same problem. His 1 ohm bias resistor failed to 83K! Needless to say, he was biasing that tube location way out of spec and didn't even know it. It kept blowing fuses and eating tubes.

 

[Tube Head]

What should I do?

 

[Soulinsane]

Sadly you are going to need an amp tech if you are not comfortable with this sort of work. I'm not sure what Randall charges and shipping to me might cost more than the repair. Hopefully there is someone local that can fix this for you.

If your are only getting a 1 on your bias reading then something is very wrong.