Simple midi controller for PX8+ (or link two?)

Q & A for building and interfacing your rack gear with Ground Control Pro and GCX-based systems.
pdxpaul
Posts: 11
Joined: Fri Nov 30, 2018 1:22 pm

Re: Simple midi controller for PX8+ (or link two?)

Post by pdxpaul » Fri Feb 22, 2019 10:54 am

So I have been using this little foot controller & it does the job - but sometimes it doesn’t work, seems to get stuck in some strange mode on startup. But only when connected by midi to the px8+ so the builder asked me to check the voltage on the midi pins coming from the switcher - being only a 5-pin connection it shouldn’t have power, right? But clearly it does have some, because I have been able to operate the controller both with or without a 9-volt adapter, the LEDs light up either way. I don’t have a multimeter with me so will have to wait a few days till I get home, but should I see any phantom power there? What voltage?

JohnClark
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Location: The Lab

Re: Simple midi controller for PX8+ (or link two?)

Post by JohnClark » Fri Feb 22, 2019 3:51 pm

The PX-8 Plus will in fact provide 9VDC Phantom Power on its MIDI In jack on Pins 1 and 3 (the pins that make the ends of the "smile"). Depending on how you are powering the PX-8 Plus, it could simply be that your supply simply does not provide enough current to power both the PX-8 Plus and the MIDI Controller.

I hope that helps!
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pdxpaul
Posts: 11
Joined: Fri Nov 30, 2018 1:22 pm

Re: Simple midi controller for PX8+ (or link two?)

Post by pdxpaul » Fri Feb 22, 2019 4:23 pm

It’s actually a Mongo (on a Dingbat...) but this also happens if I am supplying power directly to the contoller’s 9v input. Sometimes if I make sure it is all connected before powering up the Px8 it will work. Other times I have found that opening up the controller & fiddling around seems to make it start working (even just taking the back off...). But of course, I can always get it working at home, then when I get to the gig & set up it doesn’t... I’ll try putting the px8 on one of the high-current outputs on the Mongo. Thanks.

pdxpaul
Posts: 11
Joined: Fri Nov 30, 2018 1:22 pm

Re: Simple midi controller for PX8+ (or link two?)

Post by pdxpaul » Fri Feb 22, 2019 4:26 pm

So is that 9v between those two pins (one being ground...) or 9v on each of them, against the center (ground) pin? I wonder if there is a conflict between the signal ground and power ground.... if they are different

pdxpaul
Posts: 11
Joined: Fri Nov 30, 2018 1:22 pm

Re: Simple midi controller for PX8+ (or link two?)

Post by pdxpaul » Fri Feb 22, 2019 4:32 pm

One more Q: is this phantom power configurable on the px8?

pdxpaul
Posts: 11
Joined: Fri Nov 30, 2018 1:22 pm

Re: Simple midi controller for PX8+ (or link two?)

Post by pdxpaul » Mon Feb 25, 2019 10:32 am

So if you are still with me, what I have found is that the midi controller will work with the PX8 if I first start it up on an external 9v adapter. Then it will continue to run from the midi phantom power. But it won't work if I just start it up on midi - the LEDs will light up but it won't control the PX8. Almost like something has to charge up in it, but it doesn't get enough juice from midi to do so (if I leave it on 9v for a little while, then disconnect & reconnect to midi it will work - unless I leave it unplugged for too long, then it wont. . .) The builder says it needs about 50-60mA, is that more than the PX8 can pass through? I have it running on the high current port on the Mondo so it should be able to get way more than the 100 it calls for, but maybe if that's all it will pull anyway & it uses more than half for itself, then it doesn't have enough left over for the ActioN pedal to "boot up"?? Is there a spec for the phantom output current on the PX8?

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

Re: Simple midi controller for PX8+ (or link two?)

Post by JohnClark » Mon Mar 04, 2019 1:15 pm

The Phantom Power is directly wired from the Power Jack so the only consideration would be that you are taking into account the 100mA the PX-8 Plus needs + whatever you are Phantom Powering.
Power across Pins 1 and 3 of the MIDI In with Pin 1 +, and Pin 3 -.
There is nothing to configure, so not too sure what to say here. You say it works from a 9V Adapter, but what is the current spec of this adapter? If not already doing so, try using one of the 9V 400mA Outputs on your Mondo... any of the four 9V Outputs toward the Left side... maybe the controller has a large startup spike?
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InsaneJewelery
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Joined: Tue Jan 22, 2019 10:07 pm

Re: Simple midi controller for PX8+ (or link two?)

Post by InsaneJewelery » Wed Nov 13, 2019 5:52 pm

Hi, sorry for the late reply. Yes that helps. I have a Disaster Area Dmc-3XL gen3 and an older device, a Tech21 MIDI Mongoose. I think I can configure one of those (the DMC, I reckon) to handle the CC messages thru the PX-8 to my TC Vintage Delay (identical to T-Rex Replica delay).

It's a steep learning curve and I'm still struggling with the basics, but I'll persist. Thanks, John.

InsaneJewelery
Posts: 3
Joined: Tue Jan 22, 2019 10:07 pm

Re: Simple midi controller for PX8+ (or link two?)

Post by InsaneJewelery » Wed Nov 13, 2019 5:56 pm

My priority now is unlocking those 128 presets. I have the manuals for the devices but I get a bit confused with the jargon and numbers - like math, it never "sticks". Guess I'm not so smart lol.

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