Hi,

I have a 1983 Fender Showman, a solid-state amp from the Rivera era, and it has an interesting problem.




On the front panel, Channel 1 works great. However, I cannot switch to channel 2.

So I tried plugging in the footswitch to see if it was a bad switch on the front panel, and this is where it gets interesting. When I plug in the footswitch and hold down the Reverb button, I CAN switch channels, and play thru it with all channel 2 controls working, but only as long as I hold the Reverb footswitch down. As soon as I let it go, nothing.

So the switches themselves appear to work but somewhere there is a problem. The only thing i have done so far is to replace the input jack with a generic alternate- I'm not sure if that would affect channel switching or not.

On the schematic you can see where the front panel switches and the footswitch paths merge, so i have to assume that the issue is happening on the preamp board and not the logic board (but honestly i have no idea)

I'm attaching link to a PDF of the schematic- if anyone can help me trace the signal path and recommend some possible solutions that would be greatly appreciated!

https://drive.google.com/file/d/1N5OFU8sjBvo5nWdV8ukadsTESLImRg8U/view?usp=sharing

So far I have tested IC's 1 (the schematic seems to indicate this is involved with channel switching) with a multimeter in diode mode. I don't know if this is useful info or not, i dont have an o-scope and a multimeter is all i have.

Here is IC 1 and the values I got:




Hopefully someone can give me an inspiration or two on this. Thanks in advance!