Mark IIB losing power

Hi Folks

I have a lovely Mark IIB with a TC Electronics running across the Send/Return. I also use stomp boxes mainly Boss - DD3, blues driver and a Tube Screamer through the amp.

Last night the strangest thing happened after about one hour playing as i was in the middle of a solo the amp started to lose power and became very feint. I had the blues driver and the tube screamer and also the DD3 on. I switched the amp off and it semed to be ok.

I tried today to recreate but it seems to be working ok.

Any ideas?

Thanks

Steve

I had something similar a while back and it was just one of my leads

power tubes sometimes act up like that before they completely die. wouldn't hurt to have a replacement set on hand in case one craps out for good....for that matter, get some preamp tubes, too.

There's a few things you can try if you want to narrow down the possible problems. Next time you lose power, see if both channels are affected (if not, that would indicate a preamp tube problem). Also, try plugging your guitar cable straight into the effects return jack....weak sound indicates possible power amp problem (bad phase inverter or power tube). Take a cable form your Effects Send jack to another amp's input...if all your IIB's front panel controls are working OK, then your preamp tubes are probably OK. If you have EQ, switch it off and see if the low power remains....if so, your EQ is probably OK.

Thanks folks I am rehearsing tonight so will give it a go.

Steve

Check the speaker jack and plug. These tend to have a buildup of oxidation and crud over time and an intermittent power loss can sometimes be cured here.