New theory on the cause of the infamous Tunnel Vision problem - Testers needed!

[3lectr1cPPC]

I've been alerted of one photo of a 701c with vinegar syndrome - guess it's possible on the Hosiden TFT Color screens.

 

[3lectr1cPPC]

Could be too that thinkwiki.org is wrong. Just found an archived LCD listing on worthpoint and it's a sharp (for the 701c). Also possible they shipped multiple vendors as well, many many laptops did, in which case that could explain that one photo of one with vinegar syndrome.

 

[GRudolf94]

I have a few things to necro-add to this thread:

Vinegar syndrome can affect any panel where the polarizer is attached to the LCD with PVA adhesive. That is to say, pretty much every laptop LCD ever built. That includes the AM panel in a PB180, for instance. Varies a bit with climate, storage and panel supplier but none is guaranteed to be 100% immune to it.

As for vignetting/tunnel vision, it seems to be that humidity causes a change in the LC material. The tunnel vision persists for as long as the panel VEE bias supply is sustained, even if the display is not being driven. This implies some sort of capacitive effect where the cells retain charge. My Duo 250 is a pretty bad sufferer of that, with the entire panel turning 100% dark within an hour. I have a 180 panel I am setting up to drive separately from the machine to investigate further. These are all Hosiden units. Duo 280 is the same panel as the 250.

To the people with large black spots/random speckles in their panels: that's delamination. Same as trackball wounds commonly seen on PB100s.

 

[Powerbook27364]

Theo unusual thing is that I have only ever seen one hosiden panel affected by vinegar syndrome. Probably just due to the relative scarcity of them in laptops. Maybe they used a better adhesive, but I’m just guessing at this point.

I have a 280 that is basically the same as you 250 but a bit faster to tunnel in. At this point I’m just going to restore and recap my 230 and use that instead so maybe if you need any help or information from my display I can get that for you since I don’t want to bake it just yet.

With capacitance do you mean that the pixels are retaining charge or something on the board is not retaining charge and functioning properly? Why would baking help if that was the case? I’m not as technical with these yet so just trying to understand it better.

 

[3lectr1cPPC]

I think that the Hosiden color panels can be affected, like the one in the 701c. I also found a Hosiden panel in my dead CTX EzBook 800 and to me the polarizer looks about the same as in other brands. Not in their grayscale panels though, which have a very different gray-green look when off. And I’ve yet to see a single photo of a 170, 180, 540, 250, 280 or Compaq LTE laptop that used them that has vinegar syndrome.

 

[GRudolf94]

The panel retaining a bias. LCDs are driven with AC waveforms that get switched around to try and work around this persistence thing (just read any old panel datasheet and there'll usually be a pin doing that.
Mono polarizers look different because of a retardation film, this is just a filter layer.

I have a vinegar'd 180 panel - the one I intend on using for testing my ideas on vignetting (that's currently 8000mi from me) that would like a word about that.

 

[3lectr1cPPC]

I have a vinegar'd 180 panel - the one I intend on using for testing my ideas on vignetting (that's currently 8000mi from me) that would like a word about that.

Hmm interesting. Would love to see a photo of that! Perhaps the additional layer above the film on the mono displays protects the lower film from humidity and heat better, so the problem occurs much less often? Because at the very least it certainly does.

 

[GRudolf94]

It's a crop of a still from a video sent to a friend via facebook messenger in 2018, but it'll have to do.

 

[3lectr1cPPC]

Ah I do see it, interesting. It certainly seems to be much more rare on these. Look at Japanese auction listings, all the laptops from this time over there have bad vinegar syndrome, except for the 170s which all appear fine. Don’t think I’ve seen any 180s in those auctions. Wonder why.

 

[GRudolf94]

I've lived most of my life in warm coastal areas. Everything local to me from '98 down tended to have bad polarizer. Too much of my time in this cursed hobby went into scraping disgusting gunk off LCDs.

 

[3lectr1cPPC]

Ah yeah, that kinda stinks. My PowerBook 145 came from Hawaii if I remember correctly! I hope it doesn’t end up with it anytime soon.

 

[GRudolf94]

It literally stinks, lol. If you look at it sideways and it doesn't have the typical discoloring of center vs. corners you're probably fine.

I've had stuff as new as TiBooks suffer from it.

 

[3lectr1cPPC]

Yeah… I’ve seen it in 2000s stuff. But never in person! Well, I think I’ve seen a couple affected panels at the VCF Swap Meet, but none of my own laptops have had it so far. I’m praying I don’t have to deal with it for a while, but I know it’s inevitable. I’ve got mine stored pretty well though.

 

[GRudolf94]

Oh, also: it's contagious. One vinegar'd panel/machine stored offgassing in a tote with others will wreck them all, due to the acetic acid hotboxing the entire space.

 

[3lectr1cPPC]

Yep, that too. Man vinegar syndrome sucks.

 

[GRudolf94]

PVA sucks. CRTs from the 1940s-70s suffer from what could be called vinegar syndrome too (though in the CRT world it's called cataracts), due to the safety glass (a sheet of curved plexi, really) being bonded to the CRT itself with a mat of PVA.

 

[3lectr1cPPC]

Yeah I’ve seen that too, think I have it mentioned on the vinegar syndrome page on my website. Now I’ve got to update that page because I have it saying the 170/etc machines can’t get it right now.

 

[GRudolf94]

Trust me, it really is any panel. I've had them come in bad from pretty much every manufacturer: Sharp (chiefly, but that's really sample bias), Casio, Hosiden, Sanyo, LG-Philips, BOE Hydis, you name it. At this point I've probably redone 30+ PDAs, close to 20 laptops, a few oscilloscopes, maybe 15 or so calculators, the list goes on.

 

[3lectr1cPPC]

We should probably split this off to a new thread - but what’s your general strategy for repairing these panels? Where do you get good quality film? Does the new film give the same blueish appearance to the screens?

 

[GRudolf94]

Depends on the specific panel and how degraded it is. Some play nice, some the rotten filter is left behind stuck to rotten adhesive, etc. I tend to use acetone to melt away whatever's left, but that requires caution because acetone will debond driver ribbons from glass. It's that and a lot of scraping, then cotton balls to remove residue, and then trying to stick new film on without leaving bubbles. Used to buy it in bulk from a guy who sold it for car dashboard cluster repairs.

So, there's a few types of polarizer, sometimes I'd be able to source the right one, sometimes it'd be color polarizer on mono LCD... Color LCDs are much tougher to get right, especially in cases where the original sheets are too degraded for it to be possible to figure out original polarization angle. As most cases tend to be mono panels that wasn't too big a concern. Usually the polarizer I got didn't have the retarding film, so naturally black/blue on whitish yellow LCDs would acquire a greenish-yellow (think chartreuse) tinge, always with black pixels. Odd color, but much better contrast.