2:90 broken ! Help....

I was playing for an hour and a half last night and all of a sudden my sound just disappeared. There was no pop or bad noises, it just went quiet. I'm not sure if it's my Power tubes, transformer, caps etc.... The amp is still turning on and lighting up/humming and the fan is running... Just no sound. Does anybody know what the problem is likely to be ??

I have been using my mesa 2:90 into my 2x12 stereo cab, One of my speakers is 75w and the other is 120w, they are 8 ohms each and I was plugged into the 8 Ohm speaker outs.

Ive tested the speakers, these are all fine. The problem is definitely with the power amp. Its like when I flip the standby switch, nothing happens.

Fan and pilot light are on, but no sound, no tube glow, and the tubes are all cold.

Hey Stav...

If your Fan and pilot light are on, but there is no tube glow from the heaters, you have blown the filament winding on your power transformer. (Not the output transformer)

Just to be safe, in case there is a heater short within one of the power tubes, pull all of the tubes and check for 6.3 VAC across pins 2 and 7 of one of the power tube sockets. This is a rare failure though...

Also visually inspect the heater wires at the molex connector as there might be a poor connection or short due to melting insulation of the heater wires due to high current draw ..... the tubes can draw up to 10 Amps through those wires & connector.

Normally, on an amp with more room in the chassis, you could disconnect the damaged winding and add a new separate filament transformer for the heaters...but, since there is no extra room under the 2:90 chassis, it looks like you will be making a call to mesa for a new power transformer.... make sure that you have a tech replace the transformer as this is not a user serviceable part unless you are a tech.

I hope this helps

Seeya

Joe

Stav,

this sounds like a problem that was reported a couple of times. I you open up the top cover, take a look at the back left, just where the power cord comes into the interior of the amp.

Theres a plastic connector that is known to be the cause of failure/burns for the tube heater connector wire.....

Check this thread

Hope this helps....

Cheers

Magnus