Thanks for the encouragement. I'm going in.
I found test points on the power supply/motor driver board as detailed in
Chapter 12 of that manual.
+5v, +12v, +15v, +42v and +85v are all there (and all .4v high or so)
But there is no -12v. That seems relevant.
The capacitors all look OK to the naked eye.
Actually diagnosing and repairing electronics is new territory for me, but
I suppose this is where I read up, maybe pull that board out, and start
testing diodes and caps.
Thanks again Alexandre - and if you or anyone else has any clues to narrow
it down, please share.
M.
On Fri, Nov 11, 2016 at 3:38 PM, Alexandre Souza <
alexandre.tabajara at gmail.com> wrote:
How is the power supply? All rails ok? Input/output
capacitors not bulged
nor leaked?
2016-11-11 21:36 GMT-02:00 Michael Newton <michael.newton at gmail.com>:
I acquired a working HP Draftmaster RX (HP part #
7596B).
An awesome machine, 36" roll feed and 8 pens, complete with several pen
carousels, user manual, and hundreds of working pens.
I was very excited to make a splash in the art world with this thing. I
did
get it to perfectly draw a 3 color demo page from
the front panel.
Thereafter it started displaying errors on the display such as "200"
which
means it needs "mechanical
calibration".
Thanks to
hpmuseum.net I acquired the service manual
<http://www.hpmuseum.net/document.php?hwfile=1292>, which catalogs many
calibrations and self-tests to run from the front panel, including the
aforementioned "mechanical calibration".
So I power up with the appropriate front panel keys depressed to run this
calibration. The paper drive motor starts making noise, but the paper
rollers aren't turning, and the LCD display is blank.
Since that moment, the LCD display is always blank so it is currently a
boat anchor.
It's a terribly sad state of affairs. I have basic electronics and
mechanical skills and an oscilloscope so following the troubleshooting
procedures in the manual I might be able to identify a part to replace.
But
of course, parts for sale online are are rare,
expensive, used and
probably
untested.
Probably better would be lower-level repair of whatever parts are faulty
but that's probably more than I can manage at my skill level.
I'm in Seattle, WA. Is there anyone alive in the pacific NW who will pay
a
visit and help me fix this thing? (The only
company I found that admits
to
working on pen plotters is 360tech in Austin,
TX.)
Or someone elsewhere I could ship electronics parts to for test and
repair?
Or provide guidance, or help in any form at all?
thanks
M.