Michael Kelley wrote:
> I have one boardset that is working fine, the other seems to be in
>Russian, with very wierd looking vectors and garbled letters (see pic). Any
>idea what I should check on the "Russian" boardset? I know the problem is
in
>the logic board, and not the monitor. I do not have a Cinematronics
>Excorcisor, but maybe somebody who does has seen this before? I do have an
>HP5004A and a CAT box, perhaps someone knows where I should be checking
>signatures?
Without an Exorcisor the signature analyzer won't do you any good, there
won't be any stable sigs to read. The Exorcisor pumps in known, stable
waveforms
into various points on the board and the SA reads the 'downstream' sigs.
The CAT box is useless on Cinematronics (and Vectorbeam) boardsets but
you can still do alot with a scope and a set of schematics.
The display picture, from what I can see, shows that the VERTICAL lines
look OK, it's the HORIZONTAL lines that have 'creep'. Notice also, on the
text characters, that this slope looks constant but changes in the Y axis.
I'd first start looking, with the scope, at the outputs of the Y AXIS data
latches M2, P2 and S2 (74LS377). I'd guess a stuck bit on M2. If they're
all OK, work you're way back from the latches to the Secondary Accumulator
IC's T4, N4 and R4 (74LS194) following the signals SA0 thru SA11. It could
be
a stuck output there too.
Good luck and let us know what you find.
David Fish "We want...Information. INFORMATION
Melrose, MA USA You won't get it!
dfish1.at.attbi.com <- NEW By hook or by crook we will"
David.Fish.at.axcelis.com _The Prisoner_
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Received on Fri Mar 8 05:15:39 2002
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