Blackstar Club 40 MKII - Possible bad preamp

[kenbob]

I've had my Blackstar Club 40 MKII amp a few years, working perfectly, and today I turn it on and cannot produce any sound through the front input. There is a slight hiss coming through the speakers however. I leveled all the knobs, removed everything from the loop and still nothing. Plugged my guitar into the Return in the loop and clean, crisp sound.

Any ideas that might help me troubleshoot was is wrong and if I can repair it myself?

[The Dude]

If you simply jumper effects send to return with a cable, does the amp work?