OT? Apple Stylewriter problems (longish)

From: Don Maslin <donm_at_cts.com>
Date: Tue Jan 15 19:22:48 2002

On Tue, 15 Jan 2002, Mark Tapley wrote:

> Tothwolf wrote:
>
> >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.
>
> will try it. The cable was near-zero resistance,in a write-head position
> about halfway across the page, so I don't think that's it. Also the missing
> line of pixels is all the way across the page, so it's not an intermittent
> open over the range of motion across the page.

Frankly, if it is always in the same place in lines of type, the cable
deserves thorough investigation!
                                                 - don

> >Good luck with the glue, super glue and glue designed for polystyrene
> >plastics does not bond ABS plastics very well.
>
> Yeah, I know. I was being a bit facetious about the "good as new".
>
> >A cheap transistor checker? A multimeter can sometimes be used, but it
> >helps to have the pinout and specs for the transistor on hand.
>
> Hm. Replacing all of them only runs about $4.50. But Tony suggested a
> 1st-order test with my VOM (see below).
>
> >A dull knife hit with the same
> >rubber hammer on the glued seams can also work,
>
> This brick seems to have no glue. On the "wall" side (with the plug blades
> sticking out), it has three *deep* holes with what look like black painted
> metal or hard plastic beads at the bottom. Those act like bolts that are
> holding it together. I felt the label, no screw heads obvious under it, but
> I'll peel it up and check again. It's not right anyway, output is nowhere
> near the 9V it claims :-( .
>
> > 4) What am I likely to find toasted in there?
>
> >take an ohmmeter and see what the primary and secondary winding
> >resistances are.
>
> OK, will try it if/when I get the thing open.
>
> >....simply replace the whole brick.
>
> What's a good source for ancient Mac parts at bargain prices?
>
> >Of course, if you own a coil winding
> >machine and have the proper wire on hand,
>
> Um..... What's a good source for ancient Mac parts at bargain prices?
>
> --------
>
> Matt London suggested:
>
> >OTOH, Araldite (an epoxy) works a treat in my experience
>
> If everything else starts working but the cover pieces won't stay together,
> I'll try it.
>
> ----------
>
> Tony Duell said:
>
> >How many dots is this printhead? 25 connections could be 24 dots + common
> >or sowething like that. I would have suspected 1 driver transistor per
> >dot, though, and 9 dots seems very small for a modern-ish inkjet printer.
>
> Either 8 or 9. I think 8, but don't have any good evidence for that other
> than the row of 9 (what look like) driver transistors, of which one is
> slightly offset. 8 pixels would just about square with the width of the
> missing row vs. the distance between rows when I try to print a solid black
> block, but 9 might work too.
>
> The printer is 1991-93 era (about?) and was 1st generation ink-jet for
> Apple. I guessed 8 pixels based on the number of big wide traces coming
> across the ribbon cable and on the theory that it takes one big wide trace
> per pixel. Do they do some wizardry in the print head where one driver
> drives 3 pixels, but serially, or some such?
>
> >There's no easy way of telling. At least not without seeing the machine,
> >which is kind of difficult :-)
>
> I have a digital camera which produces .jpeg file pictures, about
> 450kbytes/picture. I could let you see images of many parts of it, if you
> can decode jpegs.
>
> Alternately, I have the shipping carton for it, so it becomes a matter of
> whether I'll pay more for 2-way shipping to London or for the parts I fry
> trying to debug the thing....
>
> >Is this AC or DC? In other words is the wall-wart just a transformer, or
> >does it contain a rectifier and smoothing cap as well?
>
> I made both measurements DC. I never thought to check AC before breaking
> it, as the label said DC output. I also never thought to check AC after
> breaking it. I did try the DC measurement backward, after it broke, and it
> definitely had (about) a 0.2 V DC level on it, same sense as the correct
> output had been before.
>
> >Once you get inside, it's easy to check/replace <the fuse>.
>
> I'll look forward to it. Is it easy to identify?
>
> >Could well be. Those sound like printhead drivers. I'd be inclined to
> >trace all the connections from the printhead ribbon cable connector to
> >see where they end up, though.
>
> :-) Uh oh. Tony is trying to educate me, I'll bet. What was it Huck Finn
> said about Aunt Polly? <sigh> OK, I'll give it a shot.
>
> >Read that as 2SB1243 -- which is not in 'Towers International Transistor
> >Selector'. Can you check that number, please. In fact, please post all
> >markings on the original transistors.
>
> I thought I did, unless there are more markings on the side against the PC
> board? I'll look again.
>
> >A good first check is to desolder them and then use the ohmmeter function
> >(on an analogue VOM) or diode test function (on a DMM) to check that the
> >base-emitter junction and base-collector junction test as diodes. And
> >that the 'resistance' between the collector and emitter is very high both
> >ways round.
>
> I knowed it, he's a-tryin' to eddicate me! :-)
> OK, I'll dig out the soldering iron.
>
> >To find out which pin in base, which is collector, etc, you either have
> >to look the transistor up in a databook ('Towers International Transistor
> >Selector' is a well-known one in the UK that most hardware hackers have
> >on their bench) or trace out enough of the surrouding circuitry to work
> >out at least which pin is the base.
>
> I think I get to cheat. I remember seeing "E", "C", and "B" markings on the
> PCB.
>
> ----------
>
> Pete Turnbull said:
>
> >Yes, it's a PNP power trannie, in an ATV package, which is a bit like a
> >TO220 but without the metal tab. It has a beveled edge on the front top,
> >instead of a metal tab on the back.
>
> This sounds familiar.
>
> >Pin order is ECB (opposite of the common TO220).
>
> That is what I remember from the board, though I'll check.
>
> >Near equivalent 2SD1864.
>
> Thanks! I'll comparison-shop for them both.
>
> --------
>
> All within 24 hours. Is this a *great* list to be on or what?
> Will work on collecting info tonight, responses tomorrow. Thanks very much!
> - Mark
>
>
>
>
>
Received on Tue Jan 15 2002 - 19:22:48 GMT