"robb" wrote in message
...
hello,

i posted some circuit board pics on the

"alt.binaries.schematics.electronic"

under topic ---- "pfaff UIC circuit board" to

if that will help formulate some ideas on how to repair.

thanks for any help,
rob

"robb" wrote in message
...
hello,



The way I would attack this problem would be:
Use your ohmmeter to trace the common connections from the switches to the
ribbon cable, then make sure that you have continuity through the ribbon cable.
From there, trace the circuit to whatever component(s) they connect to.
As another poster mentioned, they might be strobed using a CAS/RAS technique.
If either signal is missing, then the circuit won't respond to set of switches.
It's pretty much useless to attempt to troubleshoot your problem using the
pictures you posted. You really need to get into the circuit with your ohmmeter
and trace the circuitry. Draw a rudimentary diagram of your tracing. See
You can also power up the boards and look at the switches with a scope. You
will probably see pulses on one side of the switches. Press one of them and
trace the resulting signal back through the circuit and see where it goes away.
You'll have to find data sheets on the ICs involved, so plan on doing some
Googling. Search for the part number of the part, and datasheet. Like this:
7401 datasheet

That should get you in the ballpark.

Cheers!!!
--
Dave M
MasonDG44 at comcast dot net (Just substitute the appropriate characters in the
address)

"In theory, there isn't any difference between theory and practice. In
practice, there is." - Yogi Berra