Katana MK II "GA-FC" and "EXP Pedal" ring to sleeve and sleeve to tip voltages

Started by Daruosha, January 29, 2024, 11:17:54 PM

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Daruosha

I'd appreciate it if someone please take a voltage measurement between sleeve-to-tip and sleeve-to-ring for foot control sockets; both GA-FC and EXP Pedal on the back of Katana MK II. The sleeve is ground.

I'm trying to make a full featured DIY GA-FC footswitch with an Arduino and it is working perfectly fine, except my voltage reading between ring to sleeve is about 2.7V which is not enough to turn the Arduino on and I have to use another power supply for Arduino.

I don't have a genuine GA-FC to compare and I have only 1 Katana 100 MK II. Was wondering maybe I can ask from anyone who has a multimeter and a TRS cable to measure a few values for me. I have a feeling that I damaged the 5V rail by accidently shorting the sleeve and ring contacts in my experiments.

Elantric

Just buy one

Review this detailed GAFC TRS cable  data analysis

The TRS connection is bidirectional current loop, double MIDI Speed


Roland GA-FC Foot controller communication
https://www.vguitarforums.com/smf/index.php?topic=19959.0

Daruosha

Thanks for your response. I send sysex commands through Arduino and I can change banks and channels. As far as my requirements, everything work once I supply external 5V to Adriano. I found very similar stuff in the thread you mentioned. However it seems the supply voltage on the ring contact is 5V and on my amp is 2.7V. I read that GA-FC doesn't need any power supply or battery. Did I damaged my port? Or on Katana MK IIs, the voltage is different?GA-FC is not available where I live and if want to import it, I have to pay around 350USD which is insane (custom import, tax BS and etc...).

Elantric

GAFC derives its DC power from the Data Clock on the TRS connection
Similar to the old IVL (Canada) Remote Switch
Review all 7 pages here
https://www.vguitarforums.com/smf/index.php?topic=19959.0

Daruosha

Impressive stuff on the mentioned thread. I guess my 5V rail has been damaged. Everyone was saying the ring voltage is 5V. I screwed my new amp in 5 hours after my purchase. I guess I'm able to repair it myself. Any schematic or suggestion?

Brent Flash


gumtown

Just measured mine now, Katana Mk1 100 which sits under my desk at work.
With an un-terminated TRS plug, the open circuit voltages are 4.998v(ring) and 4.997v(tip) D.C. to sleeve/ground.
Free "GR-55 FloorBoard" editor software from https://sourceforge.net/projects/grfloorboard/

Daruosha

Quote from: Brent Flash on January 30, 2024, 08:19:49 AMWelcome to the group Daruosha!  :)

Thank you :).

Quote from: gumtown on January 30, 2024, 11:14:48 AMJust measured mine now, Katana Mk1 100 which sits under my desk at work.
With an un-terminated TRS plug, the open circuit voltages are 4.998v(ring) and 4.997v(tip) D.C. to sleeve/ground.


Thanks for your help. I don't know what happened to my unit. It looks there's a problem with my supply voltage.

Daruosha

Anyone kind enough to do the measurement on a Katana MK II?
I'm an idiot and very naive. The culprit was the TRS cable which I borrowed from my Zoom expression pedal.  The cable itself has 32Ohm DC resistance from end-to-end. Tried another hand-made TRS cable and it's working fine.

I'm so embarrassed and ashamed of myself. Sorry everybody.

I'll publish my whole design, including PCB, source code and everything for anyone who cannot afford a genuine GA-FC at rick-diculous inflated prices.

Elantric

Quote from: Daruosha on January 31, 2024, 12:25:04 AMAnyone kind enough to do the measurement on a Katana MK II?
I'm an idiot and very naive. The culprit was the TRS cable which I borrowed from my Zoom expression pedal.  The cable itself has 32Ohm DC resistance from end-to-end. Tried another hand-made TRS cable and it's working fine.

I'm so embarrassed and ashamed of myself. Sorry everybody.

I'll publish my whole design, including PCB, source code and everything for anyone who cannot afford a genuine GA-FC at rick-diculous inflated prices.

 

Weird about the 32 ohm Zoom Expression pedal cable ( not experienced  one if those)

Glad you got it going, and look forward to future posts

Daruosha

It had 32Ω not 320Ω. I didn't expect that, but again and again: never assume anything. measure twice, cut once.

Elantric

Quote from: Daruosha on January 31, 2024, 02:16:55 AMIt had 32Ω not 320Ω. I didn't expect that, but again and again: never assume anything. measure twice, cut once.
It might be a Headphone  attenuator cable


https://diyaudioheaven.wordpress.com/headphones/headphone-attenuation-adapter/