[Lengy]

After fitting two new 12AX7 tubes yesterday, my cornet2 stopped working on the right channel.  I have swopped the tubes over and the fault is still on the right channel, I did a quick voltage check and the right channel is very high (254v) at R204r.  When I fitted the tubes the board could have flexed and damaged a track or joint, but I didn't hear or feel anything unusual, does anyone have any ideas?

Thanks

Lengy

[GRD]

A little more information needed.

What tubes did you swap?  Did you switch the new AX7's between V1 and V2?  Could still be a bad tube with one channel not working. 

Or did you put back the original AX7's that were known to be good?  Then likely not a tube.

Voltage reading at R204 indicates low or no conduction through V200, which could be the tube, or the connection from the tube through 203 to ground (assuming R203 is OK - easy to measure the resistance to confirm).

Hope that helps.

[Lengy]

It was the valves, does that mean that the valve has blown in the amp on start up or it was faulty when purchased?

[poty]

I don't think it is from the power on disturbances.I would very surprised if it is from that. I think there could be either bad tubes or maybe some pecularity in pins design of the tubes.
It just comes to my head - are the tubes definitely 12AX7? Maybe the pins layout is different (because of different type of tube)?

[GRD]

Lengy,

Sounds like you're up and running now.  I'm with poty - turning on the Cornet wouldn't cause a good AX7 to fail. 

Grant

[hagtech]

Most of the time it is an interconnect - external to the phonostage.  Always swap cables between channels first when debugging.

jh