A laptop needing help. The Acer K385s, screen rebuild (Part 1)

Got this little 386 laptop from the Atlanta Historic Computing Society's free tables at their monthly meeting.It's an Acer AnyWare from 1992 with a 386 processor and 2mb of ram. Physically intact but sans battery, charger, or any documentation. Given many many early 90s laptops are crumbling to dust and plastic crumbles here 30+ years later, this little guy struck me as a trooper and deserving a bit of trying to bring it back to life, if only to take in the process.

I managed to get it booted after a bit of research, though i didn't find much about it other than the charger's output voltage pinout online, which was critical.

The lower text is from an stale old ebay description, and the Acer Anyware K386s apparently was also sold as the Acros 325SE. As far as I can tell Acros was it's own company Acer bought out around 1992, and like HP and Compaq in the mid 00s, the model naming got muddy in the merger for a bit.

With correct voltage in hand and some helpful scribbles from a previous owner on the underside where the battery once went, I bonked on a bench supply, and hoped the very simple nature of the old NiCd battery would let it wake up on life-support.

 

 

 

 

 

 

 

 

The screen is in bad shape, a typical breakdown of the light polarizing front and back layers of the LCD commonly called "vinegar syndrome". The polarizing material breaks down to acetic acid and stops working correctly. It can be fixed, but is typically very delicate and intensive work to do.

So fuck it, we ball. If slathering old plastic in hair bleach and peroxide does wonders for old plastics, tearing old LCDs to bits and slapping on new tint like it's a Dodge Neon is probably a good idea too right?

So I asked a few questions on the AHCS discord, lurked a bit on a user going by techknight who's replaced similar polarizer issues, and ordered the finest, cheapest ebay polarizer sheets that seemed likely to be large enough. I also ordered up the adapters needed to stick this computer's 80mb hard drive into a desktop pc of the late 90s, and a compactflash card adapter to replace said hard drive if it were borked, since the machine didn't want to boot into DOS before. The drive sadly just had a nearly-bone-stock install of DOS 5.0 on it. Computing archaeology is sometimes very bland that way.

 

Five screws hold the lower hinge assembly with HV backlight driver, contrast controls, power button, and lid switch. To access two of them you need to gennnntly bow up the rear port cover and slip it out.

Getting the front and rear bezel of the screen apart requires two screws from the hinge edge of the screen and lots of gentle prying, popping, and wiggling, in addition to removing the left hinge and it's cover.

With the RF shield off, the screen is tidy, and has an odd little back-bend cable on the screen ribbon. funky.

Much fiddling, gentle prying, wiggling, and cajoling later, and i had the screen mostly free to remove the front LCD polarizer. Metal screen frame is just held to the plastic screen frame with bent tabs.

A breather mid-surgery. Peep this oddly repairable and modern size of ram stick lil dude is sporting! Two whole megabytes!

 

 

 

 

 

 

 

 

It's nerve wracking taking a razor blade and pliers to a very well stuck bit of paper thin glass, but the top polarizer came free without much fuss, just a lot of slow but strong pressure pulling it up after scraping loose one corner.

 

 

 

 

 

 

The rear polarizer was much more involved to remove. The two boards that drive the vertical portion of the screen were hugging the screen's frame with their delicate flex cables held to the glass by conducive glue. Break the ribbon or glue bond and it's a dead screen. To even get those free i had to use solder wick and detach the ribbon cables tying them to the horizontal screen driver board.

Sneak a pointy razor under one edge and pull up firmly, but smoooooooth. let the pulling do the removing, this isn't like ripping off a bandaid. let it come up at it's own pace and pull just enough to keep it coming up. be careful when it's close to finished that it doesn't come flying off.

Now to "play dodgeball in a minefield", as one person from AHCS put it, who's done similar repairs. "Vinegar syndrome" is a very apt term for this effect. As soon as i got the corner of this side up the stank was strong. With the plastic sheet off, next is a scraping razor, goo-gone, and patience to get the old polarizer off.

This pic should be last. the glass sans-polarizer on both sides is nearly perfectly clear. At the edges you can just make out a bit of the conductive layer of the glass.

Half the help i got for removing and reapplying this film was a bunch of videos some dude in what looks like SE asia/oceania put up that's just absolutely manhandling modern big screens with fried polarizers with the sort of skill Turkish ice cream vendors use to play with tourists.

Worth a watch!
https://www.youtube.com/watch?v=K-0u9FqI5oM

If you plan on trying this, make sure the glass is resting flatly against a smooth, clean, flat surface. That's likely the most critical thing to not cracking it. Be very careful to not disturb the ribbon cables any more than is absolutely unavoidable, and clean the whole thing with rubbing alcohol as absolutely spotless as possible after cleaning the adhesive before reapplying the polarizer.

Photos out of order lulz.

After all that msesing around, I reapplied the new polarizer sheet to the rear and reassembled just enough to see if I had destroyed the screen along the way. I DIDN'T!

These early passive-matrix LCDs were always tough to photograph and see, and modern TFT polarizers are a bit different, but all you can get your hands on anymore. I had to get ones meant for a much later screen and cut them down to fit this one. To work correctly you need to orient the two layers at opposing orientations, for maximum contrast. Ideal orientation depends on the exact screen and polarizer but i only had one option since these sheets were only just big enough to fit one of two orientations. at 0 degrees opposed or 90. I managed to totally goof on flipping them 90 degrees to each other as I cut out and put the front layer on, and didn't catch myself until I'd fully reassembled the whole screen and hinge assembly. Thankfully on this screen it doesn't seem to have affected the display in an appreciable way.

I've been told that the ideal angle for these is 95-105 degrees opposed, and a bit of rotating the unadhered polarizer sheet makes that seem right, with a slight improvement in contrast, but these old screens were made expecting a phase correction layer and different polarizer formulation than is available anymore anyway, so it'll never look factory perfect again, and I'm okay with it as-is. Trying to redo it again seems like a recipe for accidentally breaking something irreparable.

Once today is tomorrow I'll take a crack at properly applying the front polarizing film, hopefully with fewer spots and bubbles from imperceptibly small dust than the backside, then move on to why the machine won't boot, why the floppy drive grinds on constantly like a dying case fan, and maybe some day draft up a new battery for it since even dead ones are nigh-undocumented online.