HP80: blank display, low Vcc

[andrewsiegel]

I bought a non-functional HP80 off Ebay. Aside from some corrosion from battery leakage, it's in good physical shape. The display is totally blank on power-on. Using known good batteries, I did a quick test of voltages: Vss and Vgg are good, but Vcc is showing +3V (it should be +8.2V), which might explain the blank display. I don't have a scope yet, so I can't check waveforms, but I wonder if anyone has a suggestion as to what the problem might be.