I’ve got a VFD display on board along with UPD16311 driver is made for negative voltage around -30V and i think so is display (i couldn’t find any info on display) and I’m doing it mostly from junk parts. I want to know what devices could/should contain power supply for such voltage. I’ve tried -12V from psu i’ve got lying around but it didn’t work. There’s also a chance that display itself is damaged but there’s no visual sign of it.
i didnt quite understand the issue, but if you just need -30V you can get another 30V power supply and join them in series (the ground wire from the old and the positive wire from the new supply), then you can use the joined wire as ground, the ground side of the new supply as -30V and the positive of the old supply as +30