It seemed like a good idea because the on-off switch can be a little out of reach when you're playing. As I've already voided the warranty on my Excelsior in numerous ways (tone control and red pilot light) I figured this would be a good contribution to the group.
The first thing you have to have is a footswitch like the Gretsch-ed footswitch that I got from the irrepressible Dirk Newton, who a lot of you know if you're in central Iowa.
The first step was to open it up and see what we had. There are a blue and a green wire that go to the switch mounted on the back of the vibrato control. Desolder these. The next thing to do is get a plastic Cliff type jack that is not grounded to the chassis. They're inexpensive and easy to find.
Next drill a pilot hole through the chassis and open it up with a step drill to mount the jack, but don't mount it just yet. It's best to start your pilot hole from inside so as to allow sufficient clearance and avoid damaging anything like your circuit board.
Next, solder your blue and green wires to the pins that connect to the contacts that get lifted when you put a phone plug in the jack. Mount the jack next to your 500k tone pot like mine has. I had to use a smaller pot than I had initially, so this required a few minutes to hunt thru my junk box and find a smaller 500k pot.. If you are using an Alpha pot this should cause no interference problems.
At this point you should power up your amp, plug in your footpedal and make sure that your footpedal hookup is operating properly. You can temporarily insulate the jack with a shop rag because there's voltage down there. Then you can power down, clip the pins on the jack that you're not going to use to get them out of your way, mount the jack permanently, make sure nothing's touching anything, recheck everything for proper function, and reinstall the cover.
Now, your footpedal controls the vibrato, and if the footpedal is not connected the vibrato won't work.
Great Artical. It has helped me a lot!
ReplyDeleteHI. I enjoyed your post on billm's site and I was wondering; what exactly is the paper thin shielding you replaced with sheet metal? ALl I see at the back of my amp is the electricians tube carrying the wiring from pre amp to amp. I actually can't see any shielding.
ReplyDeleteIt's aluminum flashing tape.
ReplyDeleteShould have wired the foot switch in series with stock switch to retain function without foot switch.
ReplyDeleteDisagree. In series both would have to be operational at the same time to function
ReplyDeletewith correct jack that closes foot switch terminals when unplugged.
DeleteGrounding r16 on the side that meets c8 & c9 grounds the oscillation. One wire and a regular jack and no high voltage. That's how its done on other fender amps, took 10 mins of research.
ReplyDeleteNo research needed for me. I opened it up and knew right away what needed doing, which was bypassing the on-off switch with a pedal.
ReplyDeleteThis comment has been removed by the author.
ReplyDeleteI don't really care. If people want to pick the fly shit out of pepper that's fine by me.
ReplyDeleteI tried this but it didn't work for me. I use a standard 1/4 jack with a plastic housing. was I supposed to use Rca? I mean it's off all the time not matter what I do to the switch
ReplyDeleteThe thing to do is revert to the original configuration and see if the vibrato works. If it does, then you need to do a rethink of how you wired it. If not, something else is wrong.
ReplyDeleteDoes this still allow speed control via the knob?
ReplyDeleteIt does.
ReplyDeleteHow difficult would it be to relocate the speed control knob to the footswitch?
ReplyDeleteI should think it would be pretty easy if but you'd have to add more wire to bring it out to the footpedal
ReplyDeleteCould anybody help me with possible FX loop for this amp? Thanks
ReplyDeleteHere is a link, they sell a kit, but I am totally green when it comes to electronics.
ReplyDeleteI contacted them, but was not much of a help. This is what they told me: You will have to find a place on your power supply to tap into for the power as well as a finding a point where you want to insert the FX loop.
I am not sure what it means.
http://www.mojotone.com/products/effects-loop/How%20to%20Install%20the%20Mojo%20FX%20Loop%20_5_.pdf?ck=Rayk4joDAirtKq8W&vid=Rayk4joDAi3tKghU&cktime=131869&gc=clear