Problem with my Single Rectifier

[coop21]

Last night I was adjusting the bass on channel 2 and the volume suddenly dropped. No noise, no popping just lower volume. The channel was still working but at about half power. I put the control back at its normal setting but the volume was still low. I switched back to channel 1 and it worked great.

I swapped preamp tubes one at a time with a known good set of backup tubes and no difference. I even swapped the power tubes and no difference. Channel 1 is working fine but channel 2 has lost power. The channel still works, but the bass and mid control doesn’t seem to do anything. All the other controls on that channel work fine.

I called Mesa today and the tech thinks that one of the pots may have gone bad. They are sending me new ones in the mail. Has anyone ever had a similar problem?

 

[PRSKILLER]

I`ve got a similar problem with mines. After playing a bit the sound just completely dies, I turn the standby off for a couple of minutes then back on and it will work for a bit then die again. My power tubes are still semi-new and are still lit. The preamp tubes are all dim but one. I have yet to fix it, haven`t had any time.

Here is my thread on the GearPage:
http://www.thegearpage.net/board/showthread.php?s=&threadid=106871

 

[jbird]

I would think the two above problems are from a different source. While the 1st poster notes a drop in volume, the 2nd poster is completely losing volume. I, like the 1st poster am experiencing an issue of intermittant volume decreases, though usually at low bedroom levels. If I raise the volume a little the amp will jump in volume, not in a linear fashion! I'll lower it back down, play a little, then the volume will decrease, again not in a linear fashion, but all at once. I've done a complete tube change to no avail. I have a couple more tests to do to eliminate a bad channel volume pot. I'll let you know!

 

[PRSKILLER]

Today I cleaned the loop input/output jacks and played with absolutely no problems. So glad it was an easy fix

 

[coop21]

Problem solved! Mesa tech support sent me two new pots. It turned out to be the master volume control for that channel. There was nothing wrong with the bass and mid controls, but because of the problem with the master control they didn't seem to work. It was a simple fix. The amp sounds great again. The techs at Mesa were great, they really helped me out.