Jet City JCA5212RC Footswitch

[Bacchus]

Mostly making this thread in the hope that it becomes googleable.

I seem to have lost the footswitch for my Jet City JCA5212RC. One annoying thing about this amp is that channels can't be switched without one. Even more frustratingly, the amp defaults to its Crunch setting, regardless of how it was switched the last time it was turned off. So there's no way of accessing the clean channel without a footswitch, and you aren't able to switch it to clean, then just leave it there. Having searched everywhere, I decided to make my own. This also has the benefit that I'm bound to find the original now that I've gone to the bother of making this.

I don't really use the amp for anything other than clean tones, so I didn't actually want/need a footswitch, so instead I built a small box with toggle switches that I can use. I found a wiring diagram for old Fender amps at http://www.diystompboxes.com/smfforum/ ... c=101956.0

I've rehosted the image here, again in the hope that it's easier to google for anyone else who needs it (and also for posterity, in case I decide that I do want to build something more roadworthy). I'll probably build a shorter stereo cable (this was all stuff I had lying around) and might rehouse in a smaller box that I can stick to the back of the amp. I might eventually open the amp up and add toggle switches to the front channel.

Some observations about this amp:

The clean tone really is very clean, and very, very good. Certainly worth the £250 I think I paid for it.

When powering off the amp, it switches back to the Crunch channel after the switch is flicked and as the sound is dying. What's going on here? Some sort of relay switching back to Crunch?

ftswtch1.jpg (2.17 MiB) Viewed 807 times

ftswtch2.jpg (2.26 MiB) Viewed 807 times

Lb6Dpig.png (52.86 KiB) Viewed 807 times

[dots]

pretty cool little project!

gotta be some routine in the shutdown that defaults back to a specific state. i wonder if that routine is editable or if it can be disabled.

[NickS]

jet-city_jca5212rc_sch.pdf_1.png (36.47 KiB) Viewed 777 times

Looks like the power to the relays may die before the audio goes off, causing them to go to their "normal" position - crunch. I expect the signal routing could be hacked with a knife and a bit of wire to make clean the default.


Here's their own foot switch schematic

jet-city_jca5212rc_sch.pdf_2.png (15.46 KiB) Viewed 777 times

[Bacchus]

Ah, good find. Don't know why I didn't look for a service manual.

If I'm reading it properly (and I'm probably not), I can add LEDs with 12k resistors in series between the sleeve lug and the switches, and I'll have lights?

[NickS]

Ah, good find. Don't know why I didn't look for a service manual.

If I'm reading it properly (and I'm probably not), I can add LEDs with 12k resistors in series between the sleeve lug and the switches, and I'll have lights?

Yes, the sleeve lug (ground/earth) is the red wire on their diagram, which you already take to the switches.

[Bacchus]

Hmm, a job for tomorrow, then.

[Bacchus]

This also has the benefit that I'm bound to find the original now that I've gone to the bother of making this.

Et voila:

20250826_132304.jpg (2 MiB) Viewed 672 times

[dots]

so now you have a backup.

[Bacchus]

Well I'm thinking I'll make a tiny patch cable for the home made one and keep it nearby the amp, and possibly put the footswitch one on my pedalboard.