PAL 1702

From: HÁRSFALVI Levente <>
Date: Mon, 25 Nov 2013 01:21:23 +0100
Message-ID: <>

I'm currently working on reviving a CBM 1702 monitor. I did most of the
work about a year ago, and finally succeeded to take the display back to
working order (my first ever trip to high-voltage analog land :-) ).
Then faced some problems that prevented finishing things, got short of
time and put the thing aside,... well, until yesterday.

The primary problem that I faced, that, although the NTSC version is
well documented, I couldn't find service manuals or schematic diags for
the PAL version. Parts of the PAL main PCB obviously significantly
differ from the NTSC board. Furthermore, the circuit is built up on
Japanese integrated circuits (like the M51393A) whose datasheets I
couldn't get hold of, either. Last year I did lots and lots of
measurements and could draw up parts of the circuit, also using the NTSC
service manual and Ray Carlsen's hand-drawn 1702 schematics. Those did
it for fixing some artifacts that I had faced first (distortions and
such), yet, I feel a little bit lost even with those drawings because of
the unknown functions of the chips, and still have some little artifacts
left to fix plus a full setup before assembling the thing together. If
someone knew of / had at least specific parts of the PAL 1702
schematics, help would be greatly appreciated.



PS. This display happens to be a 1702T, that is, a 1702 with a Toshiba
CRT, model 1702F, PCB assy number GE-1011A.

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Received on 2013-11-25 01:00:04

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