sunn 300t problem

[EBodious]

hi y'all

yesterday a buddy of mine had a problem with his 300t head. after several hours of practice, the amp stopped making sound. we let it cool off for a while and replugged in everything. upon power up, the power light was coming on but the tube indicator lights were off. not red, not green, just not lighting up at all.

has anyone experienced this before? any suggestions would be greatly appreciated.

thanks!!

 

[B-string]

Could be an output tube failure that blew the high voltage fuses (inside the amp head). Get it to an amp tech.

 

[jastacey]

I remember that there was a service bulletin on those amps, it was about the heat build-up and one of the issues was the amp quitting ... the output fusing is user accessible, they take a odd size fuse ..... my advise is to have a good tech service it .... it is a pretty complicated amp

 

[EBodious]

thanks guys. he opened it up last night and found a blown internal fuse. should be a cheap & easy fix.

 

[Rickenbackerman]

But WHY did it blow?

 

[jastacey]

That is my question also .....

 

[BassmanPaul]

thanks guys. he opened it up last night and found a blown internal fuse. should be a cheap & easy fix.

If only it were that simple!!! Fuses don't fail by themselves, they protect the amp from the consequences of another far more serious failure.

 

[someparts]

I like the idea of adding a fan on the Sunn/Fender 300T/Bassman 300...if you are playing one hours at a time I don't think the passive heat dissipation is enough. Had a couple solder points redone on one years ago possibly due to heat buildup. It was doing something similar.

 

[christw]

My 300 Pro has only ever blown a fuse when it had a bad output tube. Works great as a space heater in a cold garage too.