Problem with momentary loop not switching fx + stompbox hack

Q & A for building and interfacing your rack gear with Ground Control Pro and GCX-based systems.
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pedro#9
Posts: 4
Joined: Sat Nov 10, 2018 5:25 am

Problem with momentary loop not switching fx + stompbox hack

Post by pedro#9 » Sat Nov 10, 2018 5:41 am

Hello,
//HACK//
i've recently come up with a little hack that i'm pretty happy (and proud :-) ) to share with you.
The GCX is a super device, super flexible, super rugged. BUT it's a cable mess generator, at list in my setup. I was searching for ways to optimize the number of cables needed when i came up with the following idea:
Many stompboxes have their footswitch just pressing a button inside the box that tells a relay (if true bypass) or a transistor (if buffered) to switch it's state. So if you pull two wires on the pins of the switch out of the stombox and short them for a brief period of time you will switch your fx on or off. Great, it only takes 1 patch cord instead of 4 to bypass an fx or not. Actually your not bypassing it anymore but switching it on or off.

I tested this method with various stompboxes and it works great. Actually any stompbox that doesn't use a DPDT (or higher) switch can be hacked.
I've put loop 7 in "Momentary mode" and it does switch the fx as expected.

//PROBLEM//
here is the problem: i wanted to expand this switch trick to other stompboxes i have. Therefore i turned loop 2 to momentary. I can clearly hear the relay switch twice in the GCX but it won't switch the fx. I tried switching cables, switching fx. Everything works when plugged to OUTPUT of loop 7 and nothing works on loop 2.
tried on loop6 -> doesn't work
tried loop8 -> doesn't work

all loops work correctly in normal mode.

therefore my guess is that i did something on loop7 that i didn't do on the other loops i tested. Problem is, appart from going in"expander" menu and changing from "normal" to "momentary" i don't see anything else that has to be done...

if anyone has an idea i would be more than happy to give it a try.
I hope my little hack can help other people.

Pedro

pedro#9
Posts: 4
Joined: Sat Nov 10, 2018 5:25 am

Re: Problem with momentary loop not switching fx + stompbox hack

Post by pedro#9 » Mon Nov 12, 2018 8:26 am

I just tested with a multimeter and both leads are not shortening while switching on loop 2, unlike on loop 7 .
Any idea ?

JohnClark
Posts: 7131
Joined: Tue May 05, 2009 2:33 pm
Location: The Lab

Re: Problem with momentary loop not switching fx + stompbox hack

Post by JohnClark » Mon Nov 12, 2018 5:49 pm

Is there any other cable connected to these loops when you are testing? When using the Out (N.O.) as a switching jack you should have no other cable connected to any of the other jacks for that loop. In particular, if something is plugged into the Return, the Out will no longer short to ground.

pedro#9
Posts: 4
Joined: Sat Nov 10, 2018 5:25 am

Re: Problem with momentary loop not switching fx + stompbox hack

Post by pedro#9 » Tue Nov 13, 2018 2:37 am

Hello John,
yes i suspected that and therefore i had disconnected all other ports on the tested loop.
Do you agree on the way i setup my loop as momentary: expanders ->momentary (which can't be simpler !).

JohnClark
Posts: 7131
Joined: Tue May 05, 2009 2:33 pm
Location: The Lab

Re: Problem with momentary loop not switching fx + stompbox hack

Post by JohnClark » Thu Nov 15, 2018 1:59 pm

I mostly agree, yes... however, just to be 100% clear, you do need to set the Momentary status for each loop individually.
1. Enter Setup Mode by pressing both Setup Buttons at the same time.
2. Press the Expanders Button.
3. Make sure GCX-1 is set to ON. (Use the Data -/+ buttons to change this.)
4. Press the Cursor Right Button to see the Loop Status screen for Loop 1. Pressing Cursor Right repeatedly scrolls through each GCX Loop.
5. Choices are Normal (Latching) or Momentary. Set the appropriate status for each loop using the Data -/+ Buttons.
6. Exit Setup Mode by pressing either Setup Button.

After ensuring that all appropriate GCX Loops are indeed set to Momentary, I would suggest going into any Ground Control Pro preset and using the "GCX-1" screen for testing to eliminate any alternate programming of the Instant Access buttons being the problem.
1. Recall any Ground Control Pro Preset.
2. Go into the Preset Edit Mode by pressing-and-holding the Edit Button.
3. Once the screen changes, press the Select Down Button (you may have to press it repeatedly) to get to the screen that reads "GCX-1".
(At this point buttons 1-8 in the top two button rows are guaranteed to be controlling GCX Loops 1-8 on the first GCX in the MIDI path.)
4. Try your test again by first confirming that your modded pedal works in Loop 7.
5. Using the same pedal and cable, test any other loop you have set to Momentary.

The Momentary action lasts for something like 150 milliseconds so it can be easy to miss with some multi-meters.

pedro#9
Posts: 4
Joined: Sat Nov 10, 2018 5:25 am

Re: Problem with momentary loop not switching fx + stompbox hack

Post by pedro#9 » Thu Nov 15, 2018 3:39 pm

Thanks John,
There is absolutely no reason for it to work on loop 7 and not on the others.
I will unplug everything and test every single loop one at a time.
My multimeter beeped on loop 7 so I can be pretty confident that it s reliable.
I’ll definitely let you now how it goes.
Pierre

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