65 Reverb Unit Question

[65BonnieConvt]

When I first bought my 65 Bonneville convert, 2 years ago from the 3rd owner, the rear reverb unit was working but we did not use the AM/FM radio because it was extremely scratchy when turned on. In fact the last time we turned the radio with the reverb, the volume knob caused such a noise that it scared me and turned the radio off immediately.

I later had the dash-cover off and tighten the reverb switch since it was loose, along with fixing the radio. Now that the radio has been fixed, the rear speaker has no sound when put on "Reverb" on the dash switch, but does have sound when the switch is in the rear only position, BUT the volume has to be turned all the way up to get any sound out of it. The sound is not distorted when turned up.

So, I thought the speaker was blown, so I got another, but found that the new rear speaker does the same thing. So it's not the rear speaker. So, I now believe that it's the reverb unit audio driver transistors that may have been blown out. But before I play around with the reverb I have a question.

If the reverb unit is blown, why is there no sound (or very little) when not using reverb in the rear speaker only position? Is the rear speaker signal going through the unit in this position too, or is this a reverb switch issue (caused by tightening it) and not a reverb unit issue?

Guys, I need your thoughts/direction.

Thank you.
Walt

[65BonnieConvt]

Thanks Jeff. I will try that.
I was going to bypass the switch but I did not know which wires go to which speaker. I can't seem to find a wiring diagram for the 1965 reverb system in any shop manual. Is there a place I can get this?
I did test the voltage at the reverb connector and found that it does get 12volts when the switch is in the middle, but can't tell if a audio signal is getting there.

Thanks!