IBM ps/2 P70 Plasma screen voltages

From: Paul Koning <pkoning_at_equallogic.com>
Date: Thu Apr 29 08:36:19 2004

>>>>> "Thomas" == Thomas Dekker <t.dekker_at_student.utwente.nl> writes:

 Thomas> Well, I'm an electronics student at the university of Twente
 Thomas> in Holland. I got the board from a fellow student, who
 Thomas> didn't know what to do with it. The screen runs on 25Mhz,
 Thomas> reading 4 bits of pixel data at a time. Almost half of the
 Thomas> connector pins are ground, and the others are default vga
 Thomas> signal pins. It shouldn't be too hard to get some of the
 Thomas> pixels to light, I'd really like to know if it still works.
 Thomas> I don't think i have the DC-DC converter (if it's not on the
 Thomas> picture), but I can build a new power supply if I know the
 Thomas> voltages as they are coming from the DC-DC converter. Btw,
 Thomas> if you have any pictures i'd love to see them. Too bad yours
 Thomas> isn't working anymore, it's such a cool device :-)

I only know plasma panels from earlier days, when they were applied by
their original inventor to the terminals of the PLATO system. Those
were orange color, on/off only (no grayscale, or "orange scale" I
suppose).

The power for those panels was quite complex and fairly critical. It
wasn't a DC voltage at all, but rather a high voltage AC square wave
called the "sustainer voltage". The voltage was chosen so that a
pixel, once lit, would stay lit (the sustainer would "sustain" the
discharge) but pixels that were off would stay off. You could then
turn pixels on or off by pulsing X and Y wires either in phase (turn
on) or opposite phase (turn off) -- just like coincident current
addressing in core memories. So those plasma panels had inherent
memory, no refresh needed.

I don't know how far the panel you're looking at differs from those
PLATO panels.

        paul
Received on Thu Apr 29 2004 - 08:36:19 BST