Help MEEEEEEE!!!! mark IV is down 4 the count!!!!

[scottieL]

It's an older a version that I recently bought, the tubes were as old as I am so yesterday I did a complete retube with a quad of mesa grey 6L6's and a bunch of mesa SPAx7's. I left the 12At7 where it was cause I didn't know it was an At7 and kept the fifth SPAx7 as a spare. However, I was getting reverb hum and a clicking sound on the clean channels so it may be dead.

Anyway, all was well until it started to sound shrill all of a sudden, so I shut it off and took a look around back and everything. I let it cool down and then tried tweed mode, when I flipped the standby switch I got a loud pop and a loud honk as if someone plugged a speaker strait into a wall outlet. same for full power.

Initial trouble shooting:
- speaker load is correct
- all of the tubes light up evenly
- the fan still works

any insight into what is going on would be much appreciated.

 

[JOEY B.]

Check your reverb cables for good connection. Black or grey to the front of the amp, white to the rear. Cross your fingers. :wink:

 

[scottieL]

the reverb jacks are the right way around and securely facsened.

 

[scottieL]

turned out to be a fried power tube. thanks guys.

 

[JOEY B.]

Replace the new preamp tubes with the old ones, one at a time, and do a test run between each change.

 

[Monsta-Tone]

That sucks! I've been seing a lot of new tube failures lately.

At least Mesa has a warranty on their tubes.

If you swap all of the preamp tubes out, 1 at a time, it will tell you which of the old ones is still good. This will give you more spares. Sometimes the older tubes, even though they may be used, are more sturdy than newer ones.

Glad you got it fixed!