29 Dec
2009
29 Dec
'09
7:26 a.m.
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.
The small PCB mounted on the back generates a blanking signal that was
also correct.
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
required for the display. A shorted rectifier diode on the secondary
side was the problem.
Rik's suggestion did of course not help in this case, but i have seen
similar behavior to what he describes in a Compaq Portable III. Part of
the display was dark, and as the display warms up more and more of the
display became visible, over the course of a couple of hours.
Alas it was just a precursor for a total failure of the Compaq's display
later on.
I would still be interested in any schematic of the driver electronics
of any Epson electroluminiscent display.
Jos