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

[bwinkel67]

I doubt the people that designed and created those LCD panels are still at the company considering it's 30+ years old. I'm sure if you contacted the company, even if language wasn't a barrier, they wouldn't be able to help. Plus, if it was a design flaw, I'm sure they wouldn't want to admit to that "yup, we screwed that one up....would you like a refund after all these years"

 

[3lectr1cPPC]

Yeah... contacting the company would be difficult. Perhaps the best chance would be to find who was in charge of engineering at the LCD division at that time, and trying to find them. Chances would be very slim though, I highly doubt that would be successful.

 

[bwinkel67]

Also, finding out why they may fail and/or what's wrong with them may be a bit pointless, unless there is some preventative step you can take for those few that haven't failed. I think there are two paths forward for working LCDs, esp since baking them is a hit-or-miss proposition, i.e. some are just too far gone since the baking doesn't always seem to fix the issue. One path, re-create the LCD panel, which sounds far fetched, but there have been recreations of simpler panels by individuals. I have a brand new one in my TRS-80 Pocket Computer, thanks to a YouTuber that studied the old panel, re-engineered a replacement one, and got them produce to sell for $20. It's not a 100% match since the new one is bluish-green and the old one was yellow, but it works great. The other path is to find a suitable replacement that may need some tweaking. Maybe the entire assembly gets replaced and an interface board that communicates with the laptop and then translates to the panel. Noel's Retro Lab did something like that for an Amstrad luggable. Since you can get RGB/VGA out of some PowerBooks, for instance, I had thought of going that route. It obviously doesn't keep the machine authentic, but if it's that or having it be unusable due to tunnel vision, I'd choose that option.

 

[GRudolf94]

The bad panels are 640*400. That limits somewhat-direct swaps. It also complicates swapping in something else - we'd need new bezels, a 1280*800 LVDS panel, and an FPGA inbetween machine and panel.

Replicating any moderately big LCD is outrageously expensive - I've begun doing that for a machine I own, a 120*64 panel with ridiculously large pixel size and pitch, and the prototype run at the only supplier who even entertained the question would cost me close to $1000. I would suspect new glass for a PowerBook panel would be well above the $300/unit range due to small scale.

 

[3lectr1cPPC]

The PowerBook 540 panel is 640x480, the rest are 640x400.

 

[PB145B]

This is not a PowerBook, but still a Hosiden mono active LCD so I will post this here.

I recently baked the Hosiden panel on my Compaq LCD Elite 4/25e with overall VERY good results!

Here’s a before and after. First pic is after 20 minutes, and the second pic is after 2 HOURS!




Using my Palm III as a timer!

A side affect of this is it caused lots of “checking” cracks all over the polarizer. Not a huge issue as the polarizer film can be replaced and it’s not really noticeable when the system is powered on anyway.

I tried to get some photos but it was hard.




You can just barely see the cracks. The polarizer is also noticeably more “glossy” than it was.

I also have some stuff to share about the PowerBook 180 screen, some of which I discussed here.

The quest to get ANOTHER fully working PowerBook 180

Some of you remember the like-new and tunnel-free PowerBook 180 I got a while back. Well, I’m going down the rabbit hole of trying to get a SECOND tunnel-free 180! Or at least mostly tunnel-free anyway… I really want a “beater” machine I can carry around and not have to worry about. The mint...

68kmla.org

Basically, the main thing I want to say is NEVER go above 212F or 100C! Bake it for longer if needed, but don’t exceed that temp or you might permanently ruin the LCD like I did.

All was going good after 5 hours at 212F and the tunneling was much reduced, so I figured another 2 hours would be fine, but I decided to raise the temp to 215F, HUGE mistake.

Here’s what happened.


It not only “burned” the polarizer a bit, causing a yellow tint in the middle, but worse yet it created a permanent black spot of dead pixels in the screen. Tunneling is pretty much gone though! So sad that this happened.

I have another 180 now with a halfway decent screen that tunnels pretty good after about 20 minutes, almost exactly like my Compaq LTE did! So I’m hoping baking at the usual time and temp should fix this one hopefully.

 

[theonetruetom]

If the theory is that this is caused by layer separation, has anyone stuck a bare LCD in a vacuum forming table? Remove the air from the space between the layers and force them together, then add a little bit of heat to re-soften the glue?

I have neither a tunnel-vision display nor a vacuum forming table, so forgive me if this is a dumb idea.
Edit: this might also help if it's moisture related, especially if you can get a really good vacuum on it without it breaking...

 

[croissantking]

This is not a PowerBook, but still a Hosiden mono active LCD so I will post this here.

I recently baked the Hosiden panel on my Compaq LCD Elite 4/25e with overall VERY good results!

Here’s a before and after. First pic is after 20 minutes, and the second pic is after 2 HOURS!

View attachment 75700
View attachment 75701

Using my Palm III as a timer!

A side affect of this is it caused lots of “checking” cracks all over the polarizer. Not a huge issue as the polarizer film can be replaced and it’s not really noticeable when the system is powered on anyway.

I tried to get some photos but it was hard.

View attachment 75702
View attachment 75703

You can just barely see the cracks. The polarizer is also noticeably more “glossy” than it was.

I also have some stuff to share about the PowerBook 180 screen, some of which I discussed here.

The quest to get ANOTHER fully working PowerBook 180

Some of you remember the like-new and tunnel-free PowerBook 180 I got a while back. Well, I’m going down the rabbit hole of trying to get a SECOND tunnel-free 180! Or at least mostly tunnel-free anyway… I really want a “beater” machine I can carry around and not have to worry about. The mint...

68kmla.org

Basically, the main thing I want to say is NEVER go above 212F or 100C! Bake it for longer if needed, but don’t exceed that temp or you might permanently ruin the LCD like I did.

All was going good after 5 hours at 212F and the tunneling was much reduced, so I figured another 2 hours would be fine, but I decided to raise the temp to 215F, HUGE mistake.

Here’s what happened.

View attachment 75704
It not only “burned” the polarizer a bit, causing a yellow tint in the middle, but worse yet it created a permanent black spot of dead pixels in the screen. Tunneling is pretty much gone though! So sad that this happened.

I have another 180 now with a halfway decent screen that tunnels pretty good after about 20 minutes, almost exactly like my Compaq LTE did! So I’m hoping baking at the usual time and temp should fix this one hopefully.

I had the same results as you with one of my 180s, including exactly the same ‘crazing’ (checked cracks) and glossy effect. It’s not ideal but as you say not at all noticeable in use.

 

[3lectr1cPPC]

Oh yeah, I baked an LCD recently. I talked with @PB145B over discord about it but didn't post here. Compaq LTE Lite 4/25E, just like one PB145B did. Compaq is the only other laptop manufacturer besides Apple that used those screens. I got a modest improvement but it needs more baking. I didn't get the cracks on mine, but the temperature of my oven may have been lower than 212 because it's only got an analog dial, so I had to set it to an imprecise "hair over the 200 label" and hope for the best.

 

[3lectr1cPPC]

20 minutes powered on before and after. Baked for 4 hours. Very fascinating how it fixes the very edges but the inner parts still tunnel.

 

[croissantking]

Even more fascinating is that we don't know what's wrong with them or why baking helps in some cases.

 

[3lectr1cPPC]

I wish we could get in contact with a former engineer from Hosiden who worked on the LCDs, but that's probably not gonna happen.

 

[croissantking]

Any tips for selecting second hand machines in the hopes of getting a non-tunelling LCD? Is it luck of the draw or are there certain things to look out for?

 

[3lectr1cPPC]

There's honestly no way to tell unless the seller has tested it and explicitely mentioned that it doesn't have tunnel vision. I'd estimate the odds of a machine with a grayscale LCD having it has to be 90%+ at this point. The monochrome LCDs in the PowerBook 170 seem to get it less often, though still frequently. The Mac Portable, despite using the exact same LCD that the 170 does, seems to develop it far more rarely.

 

[PB145B]

If the theory is that this is caused by layer separation, has anyone stuck a bare LCD in a vacuum forming table? Remove the air from the space between the layers and force them together, then add a little bit of heat to re-soften the glue?

I have neither a tunnel-vision display nor a vacuum forming table, so forgive me if this is a dumb idea.
Edit: this might also help if it's moisture related, especially if you can get a really good vacuum on it without it breaking...

That is a very interesting idea! But yeah, I don't have a vacuum forming table either, so...

I had the same results as you with one of my 180s, including exactly the same ‘crazing’ (checked cracks) and glossy effect. It’s not ideal but as you say not at all noticeable in use.

Yeah it's unfortunate, but a worthy trade-off if you can mostly cure the tunnel vision for sure. And the polarizer film can be replaced anyway.

Oh yeah, I baked an LCD recently. I talked with @PB145B over discord about it but didn't post here. Compaq LTE Lite 4/25E, just like one PB145B did. Compaq is the only other laptop manufacturer besides Apple that used those screens. I got a modest improvement but it needs more baking. I didn't get the cracks on mine, but the temperature of my oven may have been lower than 212 because it's only got an analog dial, so I had to set it to an imprecise "hair over the 200 label" and hope for the best.

Yeah, a little more baking at the correct temp and that one should be good. Yours is actually better than mine was!

Even more fascinating is that we don't know what's wrong with them or why baking helps in some cases.

Yes, it's such an odd problem! It sucks that the best method for fixing them so far is also pretty much the worst thing for an LCD... lots of heat!

I wish we could get in contact with a former engineer from Hosiden who worked on the LCDs, but that's probably not gonna happen.

That would be awesome, but yes, very unlikely.

Any tips for selecting second hand machines in the hopes of getting a non-tunelling LCD? Is it luck of the draw or are there certain things to look out for?

Really no way to know unless it has been tested and left running for a while by the seller.

 

[croissantking]

And the polarizer film can be replaced anyway.

Hmm, but from what I’ve seen finding polariser film that doesn’t give washed out or inferior results is difficult. And then actually sticking it down, is it possible? It doesn’t have to be but then you can’t view it off angle for example.

 

[PB145B]

Hmm, but from what I’ve seen finding polariser film that doesn’t give washed out or inferior results is difficult. And then actually sticking it down, is it possible? It doesn’t have to be but then you can’t view it off angle for example.

I actually just peeled the polarizer off of one of my junk 180 screens and held some film that I got off eBay up to it, and it looks really good! Looks just as good as the original, but the film quality may vary, I don’t know.

As far as sticking it down, I’m not sure. Honestly I might would just affix it from the edges and deal with not being able to see it from the sides. I’ve heard sticking the film down is an absolute nightmare.

 

[TimeThrough]

Would looking at it under a microscope and taking a picture, then baking it, and taking a picture of that to compare help? To then possibly be able to see what the problem could be. I have a pb duo 280 that has turnnel vision where it starts in the four corners and goes until the whole screen is black but goes away after some time that I could use just gotta get a toaster. I don't want to contaminant my food. And I might be able to get access to different microscopes. Which would be right for the job?