You just lost me. I don't know what you mean by saying the 50V rail is fine all the way to the PSU (or whatever you're trying to explain). The point of origin for the power is obviously the PSU. On the PSU, there's a header [J3] that jumps off and carries that voltage (via pin 3) to the display PCB....

As this was consistent on ALL chips, I assume it has to be something common. That heavily implies the VBB rail is down. That would come in on the power supply header for the display PCB. That header supplies: 9VAC <--- Note: AC (for the display filaments) +12VDC for the analog sliders [data/volume]...

Hey y'all just picked up a vfx-sd with the keyboard calibration error for $35 and want to restore this beauty to its previous self. I've hardwired the board and checked the ribbon cable and still have cal error. I've also pulled the KPC ics and removed corrosion and reseated. I've read earlier that...

Perhaps more apropos would be that someone has already done something like this for the Korg DW-6000.

I assume voltage values are both DC and with respect to GROUND, which means I have to put my Multimeter's BLACK probe to a GROUND trace on the board and then use the RED probe to get the readings at these pins. Correct? I also get the idea of cascading the chips via the serial link, so that's cool ...

My point is that if they aren't mechanically broken then maybe it's better to recondition them. And if the entire number pad is broken then it's probably a deeper problem than just bad switches.

You might want to figure out the exact problem before trying to source new parts.

I have been looking far and wide on the internets and haven't been able to find much. Has anyone replaced the switches on the numeric pad for these? Here is a pic for reference: https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcTpHjUvxnrKBlpgrHgFGUugpzHGnLmxPVnNl4hdWijW0twGqTrNxw I'm looking fo...

Yep, you've got it. Really the biggest problem is figuring out what modern pot from Mouser, DigiKey, etc. is going to be the perfect physical fit. You'll have to measure the old one and then compare the shaft length (and so on) to the datasheet for whatever pot you're thinking of getting. Make sure ...

I thought I would make a little list here about what third-party Ensoniq Mirage libraries are known to have existed (maybe some of them have literally disappeared from the planet at this point!). There are a LOT of these I don't have, and info is scarce, so anyone with any additional information, di...

There should be two different types of VFD driver chips on the display PCB -- Texas Instruments TL5812N and TL4810AN. Unlike the 6500/11, they aren't proprietary so they should be obtainable somehow. The TL5812N is still less than $10 usually, and I'm sure there must be a stockpile of TL4810AN ICs i...

The 34085 & another under are on top of a raised circuit board. one is removable with a puller & the other, soldered into the board. here is a link https://www.instagram.com/p/BUPDUn1lT-h/?taken-by=hydedbaker The multiplexors must be buried under this board but, I can't tell. Tough to trace, the wa...

I agree with the idea that it's not so much about time frame but rather something containing a technological approach that's no longer relevant, been abandoned, superseded, etc. Vintage (for me) is something that most of the world has moved on from, the kind of thing someone might not find useful an...

I don't see anything marked 4053. There are a couple motorola chips marked 34085. Half the board is buried under the keys, though. There is certainly a parallel circuit for the right hand side & it reacts differently when the capacitor or the resistor below are bridged. The audio on that side gets ...

OK - I checked the PSU voltages on all 3 connectors and they all seemed within the specified range. So, I guess this really means the actual LED display unit is a gonner. Not necessarily true. There are chips which drive the VFD which could be the problem. Plus, even if it appears to be the display...

Looks like an axial ceramic capacitor with a value of 100 pF to me. But the context in the circuit should give you some big clues, as well as looking at the PCB markings. I'd be surprised if there wasn't something silkscreened on the board somewhere, maybe even concealed by the part itself. Like Moo...