OT? Apple Stylewriter problems (longish)

From: Mark Tapley <mtapley_at_swri.edu>
Date: Sun Jan 13 18:53:40 2002

All,
        I'm having and creating trouble with my Stylewriter 1.

Problem appeared about a month ago. One row of pixels consistently failed
to print. This happened on multiple ink-jet cartridges and after attempting
to clean the cartridge (by soaking in 95% propan-2-ol, or isopropyl as the
label says).

So I opened the thing up, breaking only a few minor plastic latch pieces on
the way (and hey, I glued them back - good as new! :-) ). I ohmed out the
flex cable from the circuit board up to the print head. The left 25 pads on
the circuit board end of the cable conduct with no more than a few ohms up
to the 25 contacts where the print cartridge attaches.

So I reassembled enough to let it print while I could still see the flex
cable. Still missing a row of pixels. The left 2 of the wide traces and the
right 2 of the wide traces connect to pins on the flex-cable connector
which show about 3V rms while printing and zero while not printing. 3V rms
means that's about what my analog Volt-Ohm-meter needle showed while
printing a solid black block.

But I could not get to the middle 4 connectors because the ribbon cable was
in the way. So I took out the circuit board, flipped it over, reconnected
all the cables (right way around? I thought so ....) and tried to print
again. The printer powered up, but as it tried to print the first time, the
power supply (wall-wart) quit working. This was also around the time my VM
probe slipped off one of the pins on the row of transistors I was trying to
check :-(. Did I short something bad, or mis-connect the ribbon cables and
do something equally bad?

The power supply (wall-wart) now puts out about 0.2 V (again on my analog
VM), vs. the 10 or 11 it used to do.

So, questions:

1) Is my (original) problem likely to be one of those transistors? There's
a row of 9 of them, right next to the flex-cable connector, with big fat
traces leading to doubled pins on the connector and thence to nice wide
traces on the flex cable. They are labelled B1243 (I think).

2) What's a less destructive way of telling which one?
        - Or is it better to just replace all of them?

3) How, short of a large hammer, do I get the power supply opened up?

4) What am I likely to find toasted in there?

More details available on request. I'm in digest mode, so it'll be a
one-day cycle unless you email me directly (mtapley_at_swri.edu), and still
probably a day because I'll read email at work and the busted machine is at
home.

Apologies if this is not on-topic. Thanks in advance for any help or pointers.
                                                                - Mark
Received on Sun Jan 13 2002 - 18:53:40 GMT