27 Sep
2014
27 Sep
'14
9:59 p.m.
On 9/27/2014 2:11 PM, Tony Duell wrote:
I'll double check things. My inspection is not made any easier by the
amount of dust covering this thing. I dare not attempt to clean it up,
but it makes finding faults visually pretty difficult.
Further
investigation reveals that the connection between FD1 on the
card edge connector (the XS05 signal) and pin 7 of the 2501 at E22 is
broken. This, I believe, is a matrix wire (or "magnet wire" from the
engineering drawings) meaning that I've got a broken wire somewhere in
the core mat.
I would just trace the tracks, both visually an with an ohmmeter,
from
the edge conector pin to the core mat and from the core mat to the diode
array. Just in case.
Incidneatlly, no matter what it says on the cover over the core mat, you
can take it off quite easily without damage. Just don't drop it on the
corse.
If it is the core address wire in the mat, you may have big problems.
Some of these mats had the cores cast onto the array of wires, no
pre-made cores that were threaded with the wires. In which case,
replacing the wire might be impossible.
My first throught was 'have a go anyway. If you wreck the board, well, it
doesn't work now'. And then I thoguth that no, you should treat it with
care. Even if you don't have the skill to fix it now, you might do so i
nthe future. Or somebody else might have a go. In any case, you don't
want ot make thigns worse.
I do have a semi-crazy idea: The H214 I have is 8Kx18 bits (i.e.
parity). If I were to disable parity on the control boards and reroute
one of the parity-related lines for this damaged section, maybe I could
get a complete 8Kx16?
I'll have to do a bit more research...
- Josh
-tony