I have a DSL 401 that was working fine. I wanted to install some different power tubes so I put them in, turned it on and heard two short static bursts, a sksksk - sksksk. Then no sound at all. Now I have nothing, no sound. The speaker is good, the F4 fuse is good, all tubes light up (though one power tube seems a little dim). I have had the bridge rectifier replaced and a fan installed. All the pre tubes were good when I made this change. It is just kind of like I can't get it out of standby mode, but the switch is connected just fine. I also get nothing out of the effects send or D.I.