M4 Phantom Power Issue - HELP!

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bbaug14

bbaug14

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I was at a show with my M4 last night and my GCP MIDI cable came unplugged at the GCP input. Plug it back in, nothing. No power. Try a different cable, nothing. Scratch my head a bit, and then I use the AC adapter that comes with the GCP for power. Pedal turns on, and the presets all work fine with the M4. Since this is all working with the AC Adapter, I'm uncertain why it's not working without it. My conclusion is that the M4 isn't sending phantom power to the GCP I think, but I can't figure out why. Could something have happened in the M4 when the cable came unplugged and then got plugged back in? Any suggestions would be appreciated. Thanks!

Oh, and I tried another cable just to be sure that wasn't the culprit. No luck.
 
bbaug14":1hphofpr said:
I was at a show with my M4 last night and my GCP MIDI cable came unplugged at the GCP input. Plug it back in, nothing. No power. Try a different cable, nothing. Scratch my head a bit, and then I use the AC adapter that comes with the GCP for power. Pedal turns on, and the presets all work fine with the M4. Since this is all working with the AC Adapter, I'm uncertain why it's not working without it. My conclusion is that the M4 isn't sending phantom power to the GCP I think, but I can't figure out why. Could something have happened in the M4 when the cable came unplugged and then got plugged back in? Any suggestions would be appreciated. Thanks!

Oh, and I tried another cable just to be sure that wasn't the culprit. No luck.
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Did you plug it in while it was still powered on? I know the Midi in the rt2/50 and M4 should be hooked and unhooked while power off. I had an issue like that with my RT 2/50. :confused:
 
Yes I did. I think I found the issue also though... Opened up the M4 and found one fuse was bad. I hope replacing this will take care of the issue (hard to tell what fuse is for what).

Good to know about powering down when plugging and unplugging the MIDI pedal. You'd think it wouldn't matter, and I'm actually really surprised it was designed this way.
 
heard some people having issues with the midi before. Now I make sure everything is powered off when dealing with midi. I know Randall discontinued the RT 2/50 and do not have anymore parts :gethim: luckily I have a great Amp tech :yes:
 
This is an issue with the M4, not the RT2/50. However, I pulled the fuse in question, replaced it, and everything is working now. I couldn't find a Slo Blow fuse, so I had to use a fast acting for now. I hope the transient current spike isn't so high that it blows this fuse eventually. At least if it does I know what to replace. :lol: :LOL:
 
Should definitely be slo-blo. The GCP does have a big turn on surge (as do many MIDI pedals) that will eventually blow the fast fuse. No doubt at the worst possible time. Not sure why it blew in the first place. The phantom power fuses are literally connected from the transformer right to the MIDI in connector. Maybe the hot pin on the end that got pulled out touched something when you were plugging it back in???? I dunno.....
 
Yeah, I couldn't understand it either. I thought maybe when it came unplugged or got plugged in that the ground connection wasn't made simultaneously with the power connection or something and that blew the fuse, but this seems highly unlikely. Regardless, I need to get some slo-blo fuses I guess. Unfortunately, they aren't readily available at local stores, at least that I've seen...
 
Oh, and 25 screws to get the top off the M4?!?!?! REALLY!?!?!? Not looking forward to installing the slo-blo I just ordered. :lol: :LOL:
 
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