"N Cook" wrote in message
...
Martin Whybrow wrote in message
news
As mentioned in a previous post, I have a Racal 9903 counter timer that
I'm
trying to repair; I found a manual that, unfortunately, has a vital
section
of the schematic missing due to a bad scan, but I have determined that
the
LSI device IC5 is probably at fault. The IC in question is, of course, a
custom part, a Ferranti manufactured 22-4601. Anyone have any idea where
I
might get one? Not holding out much hope as it's a 30 year old device,
but
you never know.
Martin
--
martindot herewhybrowat herentlworlddot herecom



that is a Racal part number it is the same LSI in my 9913 manual.
Looks possible to workaround with a multiplexer plus divider TTL etc

--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/


The manual I found has a missing section right down the centre where IC5 is
located so I can't see all the interconnections; the circuit description
indicates it acts as a counter, multiplexer and display control logic so
there's a good chance it could be replaced with some TTL. I'll contact you
by email about the manual as I see you have a 9911 manual on your list,
hopefully it's fairly similar.
Martin
--
martindot herewhybrowat herentlworlddot herecom