Mark V Shutdown

So I was playing my early 2015 Mark V today in the 10 Watt mode and CH3. I had a loud pop and then the lights on the front panel faded off. AMp still turns on and the tube will warm up. The fuse is fine.

I did some self diagnostics with changing the power tubes and rectifier tube. Still nothing. Played with the power settings and Variac/Full Power switch. Nothing. Played with the Tube/Rectifier setting on CH1 and CH2. Nothing. The channel selection both from footswitch and the knob on the back doesn't change the channel at all. No relay sound.


Any ideas? Obviously Its going to go to my boogie store that I got it from since they service them. But I figure I would check the forums to see if anybody had this issue and remedied it without having to send their amp out.

A fuse can look OK but still be blown. Double check changing the fuses. If amp powers on the mains fuse is probably good but the HT fuse might be done. Hopefully not the OT, as you already changed the tubes. You could pull the chassis and see if there’s any char or burn marks on the board near or on the power tube sockets but ultimately after fuses and tubes, next step is a tech.

There is no HT fuse in Mesa amps.

The OT has absolutely nothing to do with the power supply of the amp.

This sounds like a bad diode in the rectification circuit of the power supply, a problem that has plagued a few MKV’s due to a bad batch of diodes from a previous supplier.

Don’t go blindly poking around inside a tube amp, the power capacitors store up to 450 volts, enough to stop your heart.

Bring your amp to a Mesa certified repair center, it will get fixed correctly and without ‘guesswork’.

I mentioned the OT as he was saying the amp powers on and the tubes light up.