17 June 2014

Fixing the Reverb in a Mesa/Boogie Lonestar

This amp is one of the heaviest and by far the purplest that I have had the pleasure of fixing. It's so heavy (69 pounds, according to my bathroom scale) that I didn't even take it down to my workshop. I brought a bunch of tools up to the living room just to see if it was an easy fix. No sense lugging it for nothing, says I.

Fig. 1. Sixty-nine pounds of purple suede

I played through it for a a few minutes, of course, and the reverb was definitely on and turned up, but not audible. I tapped the tank and could hear the springs rattling around through the speaker, so the output side (black cable in Fig. 2) was good. I swapped the cable for some good ones and it still didn't work.

Fig. 2. The white cable is connected to the input jack on the reverb
tank, and the black cable is connected to the output. 

I took the cover off the reverb tank (it was mounted to a small piece of plywood), and immediately noticed a loose green wire (see Fig. 3). It was attached to the plastic connector that connects the input wire to the input transducer. I picked out the little bit of wire that broke off in the connector and reattached the wire.

Fig. 3. The culprit: a loose wire that somehow got disconnected from the plastic connector on the left.
(The cream-colored block under it is the input transducer)

I tested again, and it worked fine. I put everything back together and took my tools down to the workshop, which sure beat having to lug this beast.