No gain on Lead Channel.

[EndGame00]

I have a Mark IV combo and after a long hiatus from playing the amp, I decided to fire it up... However, Lead Channel is dead, I'm talking about no gain at all. ... I thought the preamp tubes were bad so I replaced them, still no gain. It's almost neutral clean.... I am currently running quad Mesa-labeled 6L6 GC.

Any suggestions are welcome.

 

[sduck]

The 6L6GC's aren't your preamp tubes, and have little to do with the basic sound of the lead channel. I hope you meant you changed all the 12ax7's? There's also quite a number of things that could cause this, and it'd be hard to diagnose this through a forum.

 

[EndGame00]

I know the difference between preamp and power tubes....I replaced all the preamp tubes instead of identifying which one is bad... The power tubes are still in its early life-cycle so I don't think the problem would be there....

 

[Markedman]

Try kicking it!

 

[bgh]

Just to make sure that I understand the issue, when you say "no gain" and the lead channel is "dead", do you mean that there is NO sound coming out on it, or that all you can get is clean? If all you get is clean, is it a solid clean, or is it muffled? Does the MV have any impact at all?

If you are not getting any sound at all, try disconnecting the footswitch and then selecting the lead channel via the switch on the back of the amp. Perhaps the footswitch is bad.

 

[THTH]

When I bought my MKIVB new, there was no distortion using the lead channel, only clean sound when in Tweed. Are you using full power or tweed?? I had to try two preamp tubes before there was distortion.