Hi there. I have exactly the same problem. It think it even happened the same day. However, my amp was not working properly since last friday. First off, when I turned it on it had a lot less power than before (it may have been working at like 30% of its ussual power/output). I changed the tubes but it was not that. Then I noticed that when I switched to the "loop bypass" mode at the back of the head -which defeats output and solo controls- the amp was working fine, with a lot of power (really powerful at 730! on channel's three master volume on modern mode). So I guess it is not the tubes. Then, when I found it was working fine on loop bypass mode, I decided to check once again if a miracle could have happened and turned it on (remember it was not working properly, and in the end it had almost no output (solo control was dead)). It did not start, it is like your amp: dead. But I remember that the day before I tried another set of preamp and power tubes -at 50 watt-, but forgot to put one 6L6 back, so i turned it on with only one 6L6. I noticed that, and did not turn it on -it was on stand by, put the 6L6 back and then turned it on again, and worked fine in the loop bypass mode. It was as messed up as before but at least it turned on and was fine in loop bypass mode. Now it does not even turn on, the tubes do not light up, nothing. Same as yours.
Does anybody know what could have caused the initial problem? And what could have caused the amp to be dead? Are they related -guess they are, but maybe I screwed it up in a different way when turning it with only one 6L6?
Any ideas would help. Thanks.
