OT? Apple Stylewriter problems (longish)

From: Tothwolf <tothwolf_at_concentric.net>
Date: Sun Jan 13 21:17:41 2002

On Sun, 13 Jan 2002, Mark Tapley wrote:

> 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.

Did you try flexing this cable while checking its resistance? I've
replaced a few similar cables in other printers that had intermittent
breaks in the conductors when they were flexed a certain way.

Good luck with the glue, super glue and glue designed for polystyrene
plastics does not bond ABS plastics very well.

> 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.

Sounds like it blew an internal fuse or the secondary winding it open. The
little bit of voltage you are seeing is probably leakage between the
primary and secondary windings (cheap or improperly wound transformers).

> 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).

For inkjet printers with printing problems, I usually check 3 things in
the following order:

 1: cartridge
 2: flex cable
 3: driver chips or transistors

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

A cheap transistor checker? A multimeter can sometimes be used, but it
helps to have the pinout and specs for the transistor on hand.

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

A large rubber hammer sometimes works. A dull knife hit with the same
rubber hammer on the glued seams can also work, but you have to be very
careful not to let it cut into anything inside the brick. A vice with 3/8"
thick wood blocks also can be used to squeeze the sides of the brick
slightly to break the glue seams. You need the wood to prevent the vice
from damaging the plastic. I've used all of these techniques to open
wall-warts and bricks. It takes practice to open them with little or no
damage.

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

You may find a blown fuse, sometimes directly on the transformer. You
should take an ohmmeter and see what the primary and secondary winding
resistances are.

If there is no fuse, and one of the windings is open, I'd recommend you
simply replace the whole brick. Of course, if you own a coil winding
machine and have the proper wire on hand, there is no reason not to repair
it.

-Toth
Received on Sun Jan 13 2002 - 21:17:41 GMT