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.