Reverb does not work on my Mark IV

[insearchoftone]

Hey guys,

Tonight I solved a crackling problem on the lead channel of my Mark IV by replacing preamp tube #3. Yay!!!

You guys would be proud...I actually read the manual before posting my issues!

But I still have one issue left with my Mark IV. The reverb does not work.

This amp is a late model Mark IV (B). I bought it used but I've only had it a few weeks and I have never heard its reverb yet.

I've checked the white and grey connections on the tank and near the tubes.

I am not using the optional reverb footswitch with the Mark IV. I do use the FU-3 though.

All of the tubes are stock. Even the replaced preamp #3 was from the stock extra preamp tube.

Any ideas?

Thanks ahead of time.

insearchoftone

 

[Blueshaggis]

Hey, I'm no expert but I had an idea you might try......
I'm assuming you bought it used? If so, you might try
plugging in a footswitch into the reverb switch slot and
see if it's just switched off maybe? It might work, just a thought
I had.
Barring that, call Mesa. They are tops with customer service and
would be glad to help you.

 

[insearchoftone]

Thanks Blueshaggis.
Well I tried the footswitch trick with no avail.
I was very hopeful because that idea seemed to make sence.

I called Mesa this past week.
I was told the problem was either the V4 preamp tube or the reverb tank.

Today I tried several things to try to make the reverb work.
Checked and cleaned the RCA contacts.
Swapped out V3 and then V4 preamp tubes.

I didn't make any progress until I tried the reverb tank out of my DC-5.
I uninstalled the Mark IV's reverb tank and then plugged in the DC-5's reverb tank and finally there it was...reverb. Yay!!!

So the Mesa guy was right, I had a bad reverb tank in my Mark IV.
I'll order one on Monday.

Thanks for your help.