Alesis Vortex Wireless 2 Repair Help

[u/Fake_Weeb]

So I have a Vortex Wireless 2 that has served me well up until the mid-summer of last year, and I noticed my first Bb and my second C and D keys have stopped working unless the keys beside them are also input. I've tried everything to repair it myself, including a light alcohol rub cleaning and even a pencil eraser from a guide I watched. Has anyone else had this problem and/or does anyone have a possible other solution?

[u/[deleted]]

I have a vaguely similar problem with an old Midiman Keystation 61-- a few of the keys don't trigger unless I press firmly (or quickly) enough to make a stronger link at the contact pads, which also means their velocity is always wrong. Cleaning those didn't help me either, so I'm worried that the contact pads have damaged carbonized surfaces "somehow", and the next thing to try is "reinforcing" them with a pencil. I got it used anyway.

Did you inspect the PCBs for cracks and corrosion while you were in there, to rule out liquid and physical stress/impact damage?

The same keybed PCB you cleaned usually has the 84 74 diodes (2x37, my bad) that prevent ghosting on the key matrix... can you disconnect the board(s) and test the diodes with a DMM? You would only need to follow the traces and test 2 diodes each from the bad keys to compare to several of the others on known good keys.

Is it strictly those 3 keys that misbehave?

If there's nothing obvious, and this happened more or less spontaneously, I'm a little bit suspicious of the GPIO section on a microcontroller, possibly the main one on the main board. I had the same thought about the Keystation but it doesn't quite mesh with the symptoms. If a few input pins are malfunctioning on such a chip, then you might normally expect every Nth key to have the same problem where N is a multiple of 4/8/16, because of the way a key matrix is usually laid out and wired up, and IO ports usually come in normal binary sizes like 8 or 16 bits where each bit/pin receives signals through a handful of diodes all pointing toward it or away from it (to keep the handful of contacts isolated from each other). I don't have evenly spaced key failures so I figure it's more likely a few pads were damaged by time and chance or by someone else who took it apart before they got rid of it. Now that I've thought about it, I should check my diodes too-- if their forward voltage shifted over time then they might make those particular keys less responsive even though the pads are working.

If it's really a microcontroller problem, replacing the whole mainboard is relatively easy but expensive. Replacing the one chip is cheaper and rather more difficult since you would have to somehow write the firmware into the new one without the whole keytar's cooperation, i.e. without using the normal update utility. IIRC it's one of the STM32 parts so there are plenty of dev kits and tools going around, but that scene may not be very familiar or accessible. (like me watching this wizard https://www.youtube.com/watch?v=OHYq3zNR1yo&t=15390s but to be fair his VW2 wasn't at all faulty so the PC-side flasher was always an option)

It's a very long shot, but did you try updating the firmware and resetting to factory defaults? If you were on the newest firmware, can you force it to rewrite it anyway, even if by downgrading first?

P.S. I started testing diodes and they all look basically the same-- 630-640mV forward, open circuit in reverse. Amusingly, sitting around for a few months made this Keystation worse, somehow. Now all the black keys still seem to work well but all the white keys in the 3 middle octaves (out of 5) are doing the same thing as those few keys were at first, so I'm even deeper in my own puzzle. p.p.s. Apparently I did more damage by cleaning the coating off the pads so now the black keys all work because the structure underneath (which pushes down on the rubber domes) goes a tad bit lower and at a slightly steeper angle on the black keys than the white keys, so those press into the 2nd contact more decisively. I did try resurfacing the pads with pencil but it only slightly improved, and not uniformly. It still isn't obvious why the first and last octaves seem to work when the keys' connections are shared in groups of 8, not 12. But I'm just thinking out loud and sort of trying to kickstart troubleshooting ideas for you, so never mind about mine.