Mesa Heartbreaker Head

[jvm]

I have a Mesa Boogie Heartbreaker head with a reverb issue. Both reverb pots are acting like volume controls. I have checked all components in the reverb circuit, subbed another tank and cables, subbed tubes, replaced both pots. Problem persists even with reverb tank removed, so I assume a recovery circuit problem. Any help at all greatly appreciated.

[doctor]

I have a Mesa Boogie Heartbreaker head with a reverb issue. Both reverb pots are acting like volume controls. I have checked all components in the reverb circuit, subbed another tank and cables, subbed tubes, replaced both pots. Problem persists even with reverb tank removed, so I assume a recovery circuit problem. Any help at all greatly appreciated.

I hope that the schematics will help you.

[jvm]

Thanks, doctor. I already have the schematic. I do appreciate your reply, though.

[jvm]

Anybody have any ideas at all? I am totally stumped by this one.

[Enzo]

What do you mean volume control? If you turn the two reverb controls to zero there is no sound? Or do they just add a little boost or something?

Does the reverb work?

Does the reverb sound right? Does it sound like all reverb with no dry signal? Or does the dry signal come through OK?

Look at the reverb section schematic. See up top above the reverb springs, that 3k3 resistor with 10pf cap? Is that resistor open?

[jvm]

What do you mean volume control? If you turn the two reverb controls to zero there is no sound? Or do they just add a little boost or something?

Does the reverb work?

Does the reverb sound right? Does it sound like all reverb with no dry signal? Or does the dry signal come through OK?

Look at the reverb section schematic. See up top above the reverb springs, that 3k3 resistor with 10pf cap? Is that resistor open?

Thanks for replying, Enzo. Both controls at zero=no sound. Reverb sounds ok to me but I am not sure what it was like before this problem. I will check the 3M3 resistor when I get back on the bench. Thanks again for your help.

[Enzo]

3M3? Sorry, I thought I saw a K.

[Enzo]

While you are in there, inspect all the controls on the panel. Specifically look at the back covers on each. They have a habit of pushing back and getting loose. If something hits a knob out front, the shaft can push out the back end of the pot. Easily fixed, demount the pot, squeeze down the little tabs with pliers. I doubt it is involved with this problem, but it is comon enough in the recent era Mesas, and could cause intermittent symptoms of one sort or another. The cover is what keeps the moving wiper assembly in good contact with the resistive stripe.

[jvm]

The 3.3Meg resistor is ok. I also subbed another 10pf cap with no change.

[jvm]

Solved!

The owner of this Heartbreaker had replaced both reverb pots and had them wired incorrectly. After re-wiring the pots, I replaced the faulty reverb cable and the amp works great! Thanks to all for the help in troubleshooting this beast.

[Enzo]

Great!

And there is an object lesson. One thing to always know about a repair is whether someone else has been in it, or is it in "as-failed" condition. We neglected to ask you if the amp had seen prior work.

If the amp is not worked on, we can go into the repair assuming it used to work as wired, and we search for failed parts and connections. if someone else has been in there, then we cannot assume the amp ever worked in this condition. And that would have been the case here.

[Phostenix]

Grrr. Glad you found the problem.

[hgarcia]

hello, i have the same problem, what did you do?