Another Mesa Lonestar Reverb Problem

Fig. 1. A Mesa Lonestar Special with a bad reverb tank.

I have only repaired two Mesa amps in my life. Both were Lonestars, and both had the same problem: the reverb wasn't working. On the Mesa I fixed last summer (the Purple Beast), the problem was a broken wire in the tank and an pretty easy fix.

This time, the symptom was exactly the same. The first thing I did was look all over for the reverb footswitch input, which is unmarked and tucked away under the chassis, behind the reverb cable jacks (see Fig. 2). Once I had that hooked up, I checked that the reverb controls were turned up and that the tank was correctly connected (which I did by reversing the wires and still not getting any reverb). I checked the wires for continuity and tried new ones just to be absolutely safe. Still no reverb.

Fig. 2. Here I am pointing at the very well hidden reverb footswitch jack.

I had my kids check for continuity in the tank (Fig. 3), and everything checked out. I then plugged the tank into my Blues Jr, and there was no reverb. I had a new one ordered ($20) and waited.

Fig. 3. The younguns having a go at it. Specifically, checking for continuity on the wires in the tank.

When the new one came, I was excited about the quick fix (the sooner I fix it, the happier the customer is, the quicker I get a $1700 amp off  my property, and the sooner I get paid). I quickly installed the tank and tried it out. No effing reverb. I switched cables, tried it in the Blues Jr.—still nothing.

I thought I should take a peek at the allegedly new reverb tank, so I removed it from the plywood it was mounted to. I had glanced at the inside of the tank before screwing it to the plywood before, but I missed an obvious and important detail: the reverb tank was shipped with a small piece of foam packed under the springs, which prevents them from rattling when shipped and from creating a reverb sound when installed.

With the foam removed, I installed the tank and tried the amp, and it sounded heavenly.

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.