WJ MX-50 AV-sync and GPI questions

technical questions/help
1

Hi all,

I have a Panasonic MX-50 in pretty good working condition, some of the buttons are a bit jammy from time to time but all of the properties work well, except the AV-sync. For some reason when I press the button, it does not light up or do anything. The button itself is in the best condition out of pretty much all of them, indicating to me that it has not taken the same level of abuse in the past. Boardside everything seems fine, but I haven’t dared pull out the soldering iron, as nothing is loose or looks like an obvious culprit. Anyone else have the same issue?

Another thing I wanted to ask is has anyone used the GPI input for remote controlling Auto-Take? It seems like a pretty cool way of A/B take automation, if I could somehow wire up a switch to handle CV to GPI, theoretically I could then use my Eurorack to feed it trigger signals. The only problem I have is that the manual is super vague on the specs of the GPI, and after copious searching online I can’t find a direct reference to its specifics. I know there are other devices that utilize GPI, but the specs vary wildly and I don’t want to accidentally break my beloved MX-50. Any tips of the correct wiring of a make-contact switch that could take CV trigger to ground the GPI signal (as I understand it to work), or just general information on the MX-50 GPI would be greatly appreciated. All I know right now is that the MX-50 can be setup to Auto-Take when the GPI goes from high to low, and that the connector is BNC 75, tbh it would be nice to know the voltage and amps of the GPI if possible. (I’m a noob at electronics, be gentle :slight_smile:)

EDIT update: of course 6 months of intermittant googling about CV controlled GPI got me nowhere fast, but within an hour of posting this, I found the Elk Elektronik ELKLIK that could conceivably be used as a normally open relay for operating the GPI safely. :smiley:

2

i don’t think av sync is supposed to do affect anything in video, just buffer audio in case theres noticable latency. correct me if im wrong!

gpi isn’t really 1 standard like MIDI or USB, it’s more of a catchall term for various standards for controllers and/or automation for stuff like lighting, audio mixers, and video mixers. its also a digital signal, patterns of pulses (or likely just rising edge) map to specific controls. it would likely somewhat difficult to program a video mixer via sequencers and square wave oscillators in an analog modular system, even with a complete map of instruction sets.

gpi controllers for video mixers are designed to work with devices like this

if i wanted to decode gpi signals, i’d use one of these, check the overall frequency and amplitude of the signal with an oscilloscope and either take copious notes, or figure out a way to digitally record the signals via an audio or sdr capture card and work from there. tho at that point, it might just be worth it to try and figure out how to use the editor to program things directly in its native language :slight_smile:

in terms of automating panasonic video gear with audio controllers, midi to rs-232 is a much better understood, documented, and acheivable goal.

transcribe an example of an open source design curtesy of @cyberboy666 that does exactly that.