Building a ga-fc foot controller

[Pofper]

hi, I want to build my own foot controller for my Roland 40gx, the problem is that I have no idea what's going inside the pedal, since it have 6 switches and one stereo output jack, and I can't find any resources on internet, no schematics, no circuit photos... 
here's a video showing how this foot controller works:

and a photo of the back panel of the controller:




and another of the back panel of a Roland Cube 40gx:




If you need any other informations please tell me.
Any help would be great. Thanks 

[Hatredman]

In your video you seem to press a switch in the far right that is never seen. What is it?

[Pofper]

Thanks for your reply, the button you're talking about turns on and off the reverb on the amp.
Here is the buttons fuctions from left to right:
Clean - Lead - Solo - Efx - Delay - Reverb

[feddozz]

I am fairly new to this forum but I want to throw my idea in...
Could you open the unit up and post some pics?
At least we could understand is it's just switching or there is some more complicated circuitry involved.
close up of any boards would help.
There are people here with enough experience and hawk eyes able to spot more things that you can imagine.

[Pofper]

hi feddozz, thank you for replying.
I don't own the foot controller, and I can't find circuits on internet, that's why I'm posting here! the video I attached to this post isn't mine, I just found it on youtube.
But I'm pretty sure it's not a simple switch, it has to have some sort of complicated circuit because it has 6 buttons with different functions and it is connected to the amp through a simple 6.3mm stereo jack.

[feddozz]

Ups, sorry for the misunderstanding. I just can't view youtube videos from work. From one of the replies above it sounded like you shot your own video. So I thought you could open it up.

I found this post. It is referring to a clone of a Boss F6 pedal which seems to work with the 40GX. It looks like simple switching. Have a look and see what you think.

I read the rules and it seems I can post links to other forums. Please let me know if otherwise.

[Pofper]

Thank you, the link works fine, I've already made this footswitch it has a button that toggles between lead and clean and an other that jumps to solo.

[feddozz]

>I've already made this footswitch  it has a button that toggles s between lead and clean and an other that jumps to solo.

Really? Success!!

[Pofper]

Yes, it's a really simple switching pedal!
here is the circuit I've made, the buttons are push buttons, the lead/clean button should be closed initially, the switch decides whether the solo button will be closed on rest or not! if closed, then when you press the clean/lead button you'll go from solo to lead chanel, otherwise, you'll go to clean chanel!

[Chops9012]

I'm wondering if I could have a go at this too. Have a ga 112 but would really rather not spend £75 for the footswitch. Did anyone have any success?

[anotherjim]

I could be wrong - and would be intrigued to know how it works, but...
I would think that if the ga-fc can read 2 expression pedals and a bunch of switches, then it's probably a digital serial interface. Power, ground and data on the TRS jack? 1-wire serial bus does exist.

[Beo]

I could be wrong - and would be intrigued to know how it works, but...
I would think that if the ga-fc can read 2 expression pedals and a bunch of switches, then it's probably a digital serial interface. Power, ground and data on the TRS jack? 1-wire serial bus does exist.

Either Midi through TRS, or some proprietary digital interface.

The manual (linked) doesn't say, but it's definitely a TRS... so digital.
http://roland.com/support/article/?q=manuals&p=GA-FC&id=62468246

[Chops9012]

All I'd like to build is a basic four button pedal to select each of the four channels.

Any ideas on how to do this?- I'm based in Ireland, the only place to buy the footswitch is thomann, but I'm up for doing it myself for a bit of craic.

[giglesias]

Hi everyone! I'm from Argentina and I've just bought a Roland Cube 40GX. It's an AMAZING AMP!

Unfortunately, It's impossible to buy the Roland GA-FC in Argentina, so I decided to make one.

Do you success??

Regards

[PRR]

Welcome!

> Do you success??

I have not even seen a picture of this GA-FC.

What we really need is a Schematic, of the GA or of an amp which uses it.

The Cube 40GX manual implies that basic functions (clean, lead, solo) can be switched by shorting Tip or Ring to ground. Has anybody even tried that??

The full GA can apparently switch those plus EFX, Delay, Reverb. To do this on 3 conductors, it must be sending coded pulses. There must be real "smarts" inside the GA. This would not be a trivial reverse-engineering.

[giglesias]

Hi PRR!



This is the Image.
I was looking a lot for a Schematig but it's impossible to reach on internet. I believe that coded pulses are used, but I dont know how it's works.
Althou , the side panel have 2 mono plugs for expresion pedals.Very complicated to understand how does it work thru a TRS cable.

Thanks for your help

[giglesias]

can anyone help me? 

[Pofper]

hey, sorry for late reply, but I'm losing hope, since there's no support in the net, and I can't get my hands on an actual pedal so I can see the circuit!
Otherwise, the Clean/Lead Solo footswitch is fairly easy, and I have made one myself, I've provided the circuit image here in one of the replies, but it seems like something went wrong and the image is not showing anymore, I will try to make another one and upload it =)

[Pofper]

Here is the circuit for the footswitsh
https://drive.google.com/file/d/0B01ggt8vJ3MwSEJTSnJuZ011d0E/view?usp=sharing

[Chops9012]

Thanks pofper, i am going to see if this works with my ga112, a superb amp if you ever see one going cheap.

☺