GCX + MIDI cables

[skeweredlogic]

Hi folks, not a new GCX user but new to the forums. I've been crawling silently for a while to troubleshoot, but I think my issue seems to be unique or maybe something that's too simple that maybe I didn't see it somewhere in the manual or other threads.

My rig formerly consisted of a GCX + GCP + Control Switcher, but the GCP is now gone (it was a great piece of gear - but the problems I'll describe shortly led me to believe the GCP was broken). There is one more MIDI device further downstream but isn't really relevant here, and I haven't had it in the MIDI chain for a while now while trying to troubleshoot. For further context, the GCX and GCP were purchased on ebay or reverb (can't remember which) about 6 years ago, and at that point they were already used. The control switcher was brand new when I bought it and works perfectly. Everything is plugged into a Furman M-8x^2. The GCX is using the 4-prong connector to wall-wart, plugged into the Furman.

The problem presented initially as seemingly a cable issue - over time, my cables would appear to wear out, and the GCP would receive power from the GCX but could not send messages to the GCX (the red light did not blink or anything). Switching the MIDI cable seemed to do the trick. I didn't think much of it at the time, although it got a bit expensive to replace MIDI cables periodically (and over shorter and shorter intervals). Over time, even if I hooked up a brand new, out of the box 5-pin MIDI cable, the GCP would receive power but could not send messages to the GCX.

I attempted to troubleshoot the GCP with my audio interface and an external power supply using MIDI-OX and found that I was unable to see any PCs, CCs, or really anything on the channels the GCP was supposed to be sending on, so I (stupidly) chucked it. Since setting up PC/CC messages from my DAW seemed like too much of a hassle at the time, I moved all of my pedals to the floor and dug up my old manual true bypass looper, and the footswitch for my amp.

Fast-forward to today, while this fully-manual setup works great for messing around with individual sounds and noodling, I miss having that one-touch control over my patches. So I've been messing around with converting notes on my keyboard to CC/PC messages to send through the GCX/control switcher from my audio interface. My interface is MIDI-compliant, so the pins that power the GCP don't seem to be a problem for the interface itself. However, if I leave a MIDI cable plugged into the Pedal In port for long enough (at this point less than a day), it appears that the GCX is frying my MIDI cables. If I take a brand new cable out of the box (either 3 or 5 pin, doesn't matter - I've even tried cutting the GCP power pins on a 5-pin cable to turn it into a 3-pin, no luck) and use it with the control switcher, send my CCs to change channels/reverb/etc. on my amp, it works like a dream. Once I start using that cable with the GCX, however, the GCX will stop receiving messages pretty quickly, and once that happens, if I plug that cable back into the control switcher, none of the messages go to the control switcher either.

Long story short - I went through a long diagnostic process over the course of a few years to find that it looks like my GCX is eating my MIDI cables for breakfast. Does anyone have any tips, like stuff I might be doing wrong, or perhaps a defective unit? I'm not worried about the money I've put into cables at this point (something like a hundred bucks or something over the course of 3 years isn't so bad), but I would love to be able to go back to a full MIDI-controlled rack system.

Thanks for your help!

[Marlboro05]

Hi there,

First thing I’d do is test what the wall wart is putting out, it is the cheapest part. It should be 9v AC. See if this is the case before doing anything else.
I power mine with a Pedal Power AC and it has been fine for about 7 years.

Get back to us with what you find.

Hope this helps
Cheers

[skeweredlogic]

Thanks for the quick reply! I tested the leads on the connector with my DMM and it read ~15.9-16 V AC across all combinations of the 2 pairs of the pins. I'm not really that familiar with AC so please excuse my ignorance, but from some other forum-type sites online it seems like this would be normal for a wall-wart rated at 9V AC out? It sounds like under load this would be something closer to 9V but I'm not sure what kind of load to test with or how that would even work.

If it's not normal, could the higher voltage difference be causing something weird with the MIDI signal amplitude, phantom power, or something like that?