17 Jan
2014
17 Jan
'14
6:52 p.m.
Hi, I have the drawing for the GG233, I only have an A4 scanner but can
scanthem if this will help but you will have to to do a "stick it together
job"
sounds like you have decoder problem so it may be one of the many 7442, s ,
will have to check to see which one though.
Dave
----- Original Message -----
From: "Kyle Owen" <kylevowen at gmail.com>
To: "General Discussion: On-Topic and Off-Topic Posts"
<cctalk at classiccmp.org>
Sent: Friday, January 17, 2014 6:38 AM
Subject: PDP-8/E MM8EJ G233 Troubles
Hi all,
Recently, my PDP-8/E has been acting funny. I finally had some time
tonight
to run a memory test and found that all addresses matching the pattern
XX5XX read back all zeros. Everything else tests fine. I swapped the XY
driver board (G233) and found that the problem went away.
I can't seem to locate a schematic online. My PDP-8/E preliminary
maintenance manual only describes the G227, for the 4k core board. Can
anyone help with a schematic, or judging from the symptom, point me to a
particular area on the board? I've got a 'scope and should be able to
diagnose it if I know where to start looking.
Thanks,
Kyle
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