I have two Silent 700 terminals (model 745) that I bought quite a few years
ago (nonworking). Couldn't find a schematic. Last week I just happened to
search for one - and found a complete service manual with theory of
operation and full schematics! So I got them on the workbench.
The more worn one wouldn't print anything on the paper but was otherwise
working. I found that the nylon printhead pressure adjustment wheel had
split and fallen off the solenoid shaft into the case, along with the
pressure spring. Then it would print, but I promptly discovered that the
printhead has several "dots" missing in a pattern that could not be
accounted for by the driver circuitry. I confirmed it by swapping the
printhead from the other one, and now it prints perfectly. So at least I
have one working now :)
The second one in half-duplex mode will only beep (Ctrl-G), CR and LF in
half-duplex mode, so I know the keyboard is alive and there is power.
But it otherwise won't move the carriage forwards (including space), or
print any characters at all.
Before I go to the trouble of diagnosis and repair, does anyone have a good
printhead, or know where I can find one?
No point in fixing it if the characters won't be printing properly when I'm
done...
thanks
Charles
