Tony Duell wrote:
Here's the pinout :
Gnd --o o-- Gnd
+18V --o o-- +18V
+5V --o o-- Gnd
Gnd --o o-- Gnd
Rst --o o-- Gnd
VSync --o o-- Gnd
HSync --o o-- Gnd
DotCLk --o o-- Gnd
DotsA --o o-- Gnd
DotsB --o o-- Gnd
Thanks for the pinout Tony, it confirmed my feeling that it was the
display unit itself that was faulty.
I assume you mean that the power rails were fine, and there were sensible
waveforms on the other pins.
The small PCB mounted on the back generates a blanking
signal that was
also correct.
Right. It's neen a long time since I've looked at one of these displays. Is
this a little PCB on top of the display PCB itself?
And I
didn't try to draw out the display module itself. It seemed to be
all custom stuff. There is what appears to be an HV PSU on the display
module PCB that it probably repairable -- I can try to figure it out if
you think that's the problem.
This was indeed the culprit : it is a 5V to 5V isolation converter, used
to power some logic that is required on the far end of high voltage
Where does it get the HV from? It must be generated on the display board
itself.
required for the display. A shorted rectifier diode on
the secondary
side was the problem.
At least it was something you could repair, and not one of the custom ICs.
I would still be interested in any schematic of the
driver electronics
of any Epson electroluminiscent display.
So would I. If I had some clues as to what I was looking at, I'd be
prepared to take one of my IPCs apart again and see how much of the
display I could figure out.
-tony