Fender Dual Pro A/B switch, Footswitch Problem

[Perkinsman]

The a/b works fine when you manually slide the switch on the front panel but only when the footswitch isn't plugged in, which is the way it's supposed to work per the manual. The problem is when I plug the footswitch in, the a/b doesn't engage and the little red pilot light on the footswitch doesn't come on. I cleaned the switching jack contacts but no change. I do hear a little buzz and a soft click in the Omron relay. Is the relay a common problem with these or is the footswitch more likely to cause this problem?

[Jon Snell]

Have you got AC voltage on the pedal?
Are the diodes OK?

[Enzo]

TRied more than one cord?

[Perkinsman]

Yes, tried a different 1/4” cable but no difference. Not sure what the purpose or where to test AC at.I played with the input jack to the footswitch. When I install it 3/4 of the way into the jack, both the Effects & Channel Select lamps came on brightly BUT neither Effects nor Channel Select worked when I plugged the guitar in. Then, with the input fully installed, neither lamp shines brightly, instead both lamps start flashing dimly AND only the Effects works when engaged, but not the Channel Selector.

[Perkinsman]

Add’l pics

[Enzo]

Your footswitch has a plain old guitar cord from amp to pedal. Plug that cord into the amp jack, like in your photo. Unplug it from the footswitch itself. Now at the free end, measure for AC voltage between tip and sleeve. That is what the FS you are using needs, but see later...

The relay is not the problem, because the thing works without the FS.

I note your plug is not all the way plugged in. A much more useful photo would be a good view of the part of the jack inside the amp, the exterior just shows a plug in a jack.

But assuming your cord is OK, and the jack in the amp is OK, your FS must be faulty.


The only schematics I have are for the Dual Professional from about 1995. The FS in your photo is not correct for that amp. Is your "Dual Pro" a different amp? The Dual Professional I see wants a plain old TRS plugged stomp switch with two buttons. It won't be happy with that Fender LED thing.

[g1]

If that's the late 90's version, that's the wrong footswitch like Enzo said. Schematic attached.

[Perkinsman]

There is another 2 button ”oval” footswitch in the amp but it has rca connectors. Would a Stereo 1/4" Male TRS to Dual RCA Female Stereo Breakout Y-Cable ne the correct adapter?

[Enzo]

Or lop the RCAs off the end and wire a TRS plug on the wire.

[Perkinsman]

Stereo or mono?

[Enzo]

TRS means tip-ring-sleeve. We don't like to call them stereo. After all there is no left and right channel here, is there? A "mono" would be just a TS plug.

[Perkinsman]

Thank you!