Acoustic G100T needs help

[AudioMirage]

Hi,
I have an Acoustic G100T with a problem.
I did a cap job on it which restored it to it's proud glory.
I replaces every electrolytic cap in it with FTs and Sprague Atoms. Plus a few ceramic discs changed to Sprague Orange drops. Opened the pots and scrubbed them out with deoxit.

On firing it up she rocked. But only for a short while. The amp still plays awesome, but the channel switching circuit doesn't work nor does the reverb.
It appears to be in channel 2 as the Volume2 knob controls the volume and the Volume1 knob does nothing. Neither of the channel indicator LEDs are lit.

Anyone had this happen? I have looked for all of the obvious, I.E. loose / broken wires to no avail.

[AudioMirage]

I forgot to mention.
When I fired the amp up after the cap job, the channel switching circuit did work.
Don't know about the reverb because I still had the chassis on the bench and had not connected the reverb tank.
When I put the chassis back in the cabinet and connected tank is when I realized that the reverb wasn't working.
After removing chassis again is when the channel switching circuit ceased to function.

[TomCarlos]

There are several threads on this site for the G100T. Do a search, get yourself a schematic, and maybe you can find some help (as to where to start troubleshooting) from those threads.

[AudioMirage]

Have done all of that. No answers. Was hoping someone had the same trouble.

[DrGonz78]

Have done all of that. No answers. Was hoping someone had the same trouble.

That would take all the fun out of it. Looking at the schematic there is an "E" supply 60v that feeds the returns for the reverb. Also, tied downstream is the "F" supply 19v which feeds the channel switching circuit and reverb drivers. Please confirm whether these voltages are present or not.

[52 Bill]

Dr. Gonz is right, it sounds like low voltage supply is missing.

The default mode is channel 2 on when the switching is off. These amps use Vactec cells with a 9 volt incandescent lamp and two cds cells. Sometimes the bulbs will burn out, but can be replaced with a little work.

[pdf64]

I thought that vactrols tended to use an LED rather than an incandescent lamp?

I noticed on the schematic that the channel footswitch jack socket looks to be isolated from the chassis 0V; if that got changed somehow (eg isolating washers removed, the insulation got otherwise compromised, or the socket replaced by a regular socket) the system may not work.

[52 Bill]

I thought that vactrols tended to use an LED rather than an incandescent lamp?

As far as I know all of the current ones do, but back in the '70s when this amp was designed they still made the light bulb versions.

Even though both versions were available back then, my guess was that there was some characteristic of the lamp versions that made them more desirable in this design. Could be the slow response time of the lamp would give it a smoother transition from channel to channel.

[AudioMirage]

Thanks for the leads. I am off tomorrow and will put in some time on it.
Where are the vac-trols located? On small PC board that all of the pots are attached to? I should be able to bypass them to see if they are the true cause.
Fsw jack is isolated from chassis.

I like working on old Fenders much better. No hidden traces on underside of PC board!!!

[52 Bill]

Where are the vac-trols located? On small PC board that all of the pots are attached to? I should be able to bypass them to see if they are the true cause.
Fsw jack is isolated from chassis.

Check the power supply voltage first, the Vactrols are probably the last thing to check.