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

3lectr1cPPC

Well-known member
It’s up to you which you pick, bake and risk damage or deal with the tunneling. Neither option sounds great…
 

Powerbook27364

Well-known member
It’s up to you which you pick, bake and risk damage or deal with the tunneling. Neither option sounds great…
Yeah it’s going to end up pad in some way or another.

This is the current state of the panel
 

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bwinkel67

Member
I wish someone would design new displays. I think there should be enough PowerBook users out there to make it worthwhile. They are such nice machines after all. A TRS-80 Pocket Computer enthusiast made replacements for both the TRS-80 Pocket Computer 1 and 3 and you can buy them for only $20. Granted these were simpler displays, but if you go through his design process (he has a few videos) it was actually tricky to reverse engineer those specialty designed LCDs. It may be simpler to take a more standard form-factor and just get the resolution and size right.

If I couldn't have fixed mine (or it degrades again) I would have looked into creating my own replacement LCD using off-the-shelf parts, similar to how Noel did it for his Amstrad PPC. In fact, with the PB 180 supporting color, I might have tried to get the signal from the external video connector to attach to an embedded color LCD.

Part 1:
Part 2:
Requiem:
 

Paralel

Well-known member
What that guy did is nice, but I think most people are interested in preservation and repair of original materials, along with reproduction of parts contemporary to the machine. Any solutions that are technically augmentations are usually workarounds for situations where reproduction of parts contemporary to the machine is not reasonable, such as with the 2.5" rotating platter drives that Apple used in the Powerbook series. No one in the hobby space has the ability to fabricate 2.5" rotating platter drives, it just isn't reasonable. All the true augmentations, such as the expansion of the memory of the LC III, are actually tapping into the potential of the machine that was never realized. I find this tends to be essential to most true augmentations, they are meant to bring out unutilized potential that exists for whatever reason.

For the blackbird series, what this guy did, by upgrading to a color screen, is like taking a 540 with tunnel vision and sticking a color screen in it. All that does it make it a 540c. There are plenty of 540c's with original screens that don't have any issues. Anyone who wants an actual 540 is interested in the 6-bit grayscale screen, which is unique to the 540. Saving the screen is the essence of the battle against tunnel vision.
 

Powerbook27364

Well-known member
What that guy did is nice, but I think most people are interested in preservation and repair of original materials, along with reproduction of parts contemporary to the machine. Any solutions that are technically augmentations are usually workarounds for situations where reproduction of parts contemporary to the machine is not reasonable, such as with the 2.5" rotating platter drives that Apple used in the Powerbook series. No one in the hobby space has the ability to fabricate 2.5" rotating platter drives, it just isn't reasonable. All the true augmentations, such as the expansion of the memory of the LC III, are actually tapping into the potential of the machine that was never realized. I find this tends to be essential to most true augmentations, they are meant to bring out unutilized potential that exists for whatever reason.
I agree with that there is definitely an element of keeping originality. The displays would be nice for those people who don’t mind sacrificing a damaged or broken panel for a new one.

Even as a replacement for broken or missing displays it would have a purpose.

There are solid state adapters for the 2.5” drives which I think is quite useful given that many of the originals have failed and they are quite hard to get a replacement for. Sure it may be faster and remove authenticity but it is the only option in manny cases especially if you live in a country with less availability.

The display would only really be a benefit it my opinion since the originals will most likely keep on dwindling until none are left unaffected. If that happens the only current fix is baking which overtime will lead to damage.
 

Paralel

Well-known member
Or perhaps a humidity test would help. Bake a screen to fix it, then put it next to a humidifier and see if it comes back. That would be additional observational data. Then if it comes back you can simply re-bake it to get rid of it. For those that think it's humidity, it should be an easy and safe test.

The reason I'm skeptical of moisture is that if there are gaps in the screen that cause moisture to enter, then why would baking it keep it away for over 6 months, especially when part of those 6 months are July, August, and September; very humid months. Wouldn't it just enter again when the pressure changes during some minute expansion of the panels, while sucking in air? Also, having seen the way vapor behaves between window panes, it doesn't disappear as orderly and timely as the LCD panel has done for me when shutting down and having it completely go away in a somewhat set period of time. I would think it might persist for much longer (days) around the edges depending on humidity conditions outside...i.e. during really humid times, wouldn't the tunneling just stay as is?

I'm not discounting it as a theory completely, but I feel like that's been the main fallback and thrown out there as fact. Heating and cooling between two close surfaces and their potential movement away from each other when not fastened together due to lack of sealant seems just as plausible and potentially could be more constant. As the screen warms up due to electricity flowing through it, the panels start minutely separating and that could be causing the constancy of the tunneling pattern. Just as heating could be vaporizing moisture between panels, so could it be re-flowing sealant, causing less movement between those panels. The latter would not be impacted by by outside condition. Why does vacuum sealing also work? Again, could be sucking out the moisture, or it could be pushing the panels together, thus creating a tighter bond (note, I've only heard anecdotal stories about someone trying that technique). Why does storing it in rice (or some other dehydration method) for 10 years work (that's one that I heard)? Well, again, that's a hard one, to say something worked because it was stored for 10 years. I mean, how was it stored? How bad was it before hand? Was it completely cured?

If it is a separation issue and a vacuum environment is able to apply enough pressure to partially correct the issue, it should be eminently testable using a constant, even weight/pressure across an impacted screen for a given period of time and test it for improvement. If there is no improvement then we would know with a reasonable degree of certainty it is not a separation issue. It would be a reasonable test since it would remove the vacuum element that could improve an LCD for either cause, as well as remove the thermal repair element since that would also work for both causes.

Is anyone up to testing the theory?
 

bwinkel67

Member
If it is a separation issue and a vacuum environment is able to apply enough pressure to partially correct the issue, it should be eminently testable using a constant, even weight/pressure across an impacted screen for a given period of time and test it for improvement. If there is no improvement then we would know with a reasonable degree of certainty it is not a separation issue. It would be a reasonable test since it would remove the vacuum element that could improve an LCD for either cause, as well as remove the thermal repair element since that would also work for both causes.

Is anyone up to testing the theory?

Well, I just heard anecdotally that someone had argued the thing to do is use the vacuum method to remove (and thus prove its) moisture. My counter argument was that that type of vacuum sealing could apply enough pressure to suck the panels together as well and so it wouldn't necessarily prove moisture. I don't think it would disprove the separation issue since there is no re-flowing of adhesive, and pressing two things together that aren't held together by adhesive, when the pressing force releases, may come right back apart. Of course you could have one instance where it works (adhesive still has something left and force caused a bond) and one where it doesn't (just too dried up), so it will yield inconclusive information.

Again, put a humidifier next to a running, fixed (baked), LCD screen for a while (don't know, days maybe, or a week) and see if the screen sucks it back in...that'll prove it's moisture related. I would not do that with a primary model (I won't be doing it with my PB 180) since it could destroy or degrade other parts of the machine, but for those that may have a bunch of old PB's lying around, where some are in bad shape (broken plastic,, etc) and used primarily for spare parts, they could put something together temporarily, try and bake the screen to fix it, and then try this approach to see if moisture returns. That would be a bit more conclusive since, if no moisture comes back then why not? I suppose maybe the moisture was driven out AND the seals re-flowed to close things up? I mean that could be too. So perhaps a baseline test is to find a not-so-bad LCD, then not bake it, and do the humidity test to see if it gets even worse more quickly. Really, only someone with a stash of these machines could do that test.
 
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bwinkel67

Member
What that guy did is nice, but I think most people are interested in preservation and repair of original materials, along with reproduction of parts contemporary to the machine. Any solutions that are technically augmentations are usually workarounds for situations where reproduction of parts contemporary to the machine is not reasonable, such as with the 2.5" rotating platter drives that Apple used in the Powerbook series. No one in the hobby space has the ability to fabricate 2.5" rotating platter drives, it just isn't reasonable. All the true augmentations, such as the expansion of the memory of the LC III, are actually tapping into the potential of the machine that was never realized. I find this tends to be essential to most true augmentations, they are meant to bring out unutilized potential that exists for whatever reason.

For the blackbird series, what this guy did, by upgrading to a color screen, is like taking a 540 with tunnel vision and sticking a color screen in it. All that does it make it a 540c. There are plenty of 540c's with original screens that don't have any issues. Anyone who wants an actual 540 is interested in the 6-bit grayscale screen, which is unique to the 540. Saving the screen is the essence of the battle against tunnel vision.

I personally do like keeping things original where possible, but when your screen gets as far gone as I've seen them go (even Powerbook2736) it's either not usable or you find another PB and grab its screen -- in which case you now have one without a screen. So I see scenarios where doing what Noel did makes sense. If you are a collector and don't like hardware mods to your collection, I certainly respect that. But some retro hobbyists also like to mod their machines to improve/upgrade them, and that's also perfectly fine. Now if the screen is perfect and someone does that, I could understand some frustration from folks that have an imperfect model seeing a good one destroyed, but if the screen is crappy with a bad tunneling effect, then why not fix it to make the rest of the machine enjoyable. For me, I like using the PB 180 (even taught a lecture for one of my classes) and if the tunneling comes back and I couldn't fix it, I would look to mod it to be able to continue to use it (and likely it would be a fun project). It would actually be an improvement over the PB 180c model since I'd put in the bigger screen. I also enjoy watching Action Retro (another YouTuber about the same size channel as Noel), who is constantly upgrading all of the Macs in his collection. I think there is plenty of room (and machines) to do both.

Except drill a hole in the plastic...that's a step traveled too far for me :)
 

Paralel

Well-known member
Well, I just heard anecdotally that someone had argued the thing to do is use the vacuum method to remove (and thus prove its) moisture. My counter argument was that that type of vacuum sealing could apply enough pressure to suck the panels together as well and so it wouldn't necessarily prove moisture. I don't think it would disprove the separation issue since there is no re-flowing of adhesive, and pressing two things together that aren't held together by adhesive, when the pressing force releases, may come right back apart. Of course you could have one instance where it works (adhesive still has something left and force caused a bond) and one where it doesn't (just too dried up), so it will yield inconclusive information.

Again, put a humidifier next to a running, fixed (baked), LCD screen for a while (don't know, days maybe, or a week) and see if the screen sucks it back in...that'll prove it's moisture related. I would not do that with a primary model (I won't be doing it with my PB 180) since it could destroy or degrade other parts of the machine, but for those that may have a bunch of old PB's lying around, where some are in bad shape (broken plastic,, etc) and used primarily for spare parts, they could put something together temporarily, try and bake the screen to fix it, and then try this approach to see if moisture returns. That would be a bit more conclusive since, if no moisture comes back then why not? I suppose maybe the moisture was driven out AND the seals re-flowed to close things up? I mean that could be too. So perhaps a baseline test is to find a not-so-bad LCD, then not bake it, and do the humidity test to see if it gets even worse more quickly. Really, only someone with a stash of these machines could do that test.

This kind of test wouldn't work. Once a screen is treated with baking, whether it is in a high humidity environment or not, it would be impossible to determine the cause of progression, whether it is humidity, or separation, since either or both could be occurring and it would be impossible to tell them apart just by observation, which is the crux of the current issue.

The best test case would be to use a desiccator filled with a powerful desiccant and place the screen inside for a period of time necessary to push all the water out of the screen. If it was hooked up immediately and a noticeable improvement was seen, then it would have to be moisture related since the only thing about the screen that would have changed would be the water content. The only issue I can think of is I don't think I've ever seen a desiccator large enough to fit a Powerbook screen inside. Only someone on a university campus would have access to equipment like that.
 

bwinkel67

Member
This kind of test wouldn't work. Once a screen is treated with baking, whether it is in a high humidity environment or not, it would be impossible to determine the cause of progression, whether it is humidity, or separation, since either or both could be occurring and it would be impossible to tell them apart just by observation, which is the crux of the current issue.

The best test case would be to use a desiccator filled with a powerful desiccant and place the screen inside for a period of time necessary to push all the water out of the screen. If it was hooked up immediately and a noticeable improvement was seen, then it would have to be moisture related since the only thing about the screen that would have changed would be the water content. The only issue I can think of is I don't think I've ever seen a desiccator large enough to fit a Powerbook screen inside. Only someone on a university campus would have access to equipment like that.

I don't agree with that. I've had good luck now with my screen as it's worked for 6 months after baking. If it's moisture related and not due to re-flowing the seal adhesives, then if I put a humidifier next to it for a prolonged period of time and would run it regularly, I would suspect in a week or two it should show signs of tunneling again -- why wouldn't it? If it did, that wouldn't be due to separation since it's been fine otherwise (the odds of it separating right after 6 months when I start the moisture tests are pretty low). If it's not resealing things then the gaps would still be there and all that baking accomplished was to vaporize the water. Also, what about a screen that is only showing light signs of tunneling that has not been baked, and you expose it to more moisture by having a humidifier near it running....that should deteriorate faster (i.e. tunneling spreads further and faster). I do think those tests ought to show if moisture is getting in or not so that we can conclude that it's moisture related. They are easy to do (humidifiers are cheap)...it just takes someone with more than one PowerBook with at least one screen with a slight case of LCD tunneling willing to give it a try.
 
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3lectr1cPPC

Well-known member
Finally got my 170 apart. Stupid broken standoffs.
Here’s the LCD panel and serial number. Don’t know how to decode a manufacture date of this, maybe @Paralel does. Completely unaffected by TV. Funny how different these look from passive matrix panels.
7F383E80-2499-4B11-9FFA-DBD518995689.jpeg
AEC5E024-FA49-4930-9EFD-306C3245F0EA.jpeg
82362DE8-991B-466E-872B-E900DF641DE9.jpeg
 

joshc

Well-known member
I dunno, if I could have a 68k PowerBook with a new display, I would jump at it. I am personally not so bothered about originality if I get a working screen that will never have tunnel vision problems. B&W or greyscale would look so great on a modern crisp display.
 

3lectr1cPPC

Well-known member
Just tried to submit this and the database crashed for a few minutes! It seems to be back now though...

It comes down to preference, but I'd be bothered by it. If the modern panel was a 1-1 match for the original in terms of looks, I wouldn't be, but the
limitations and retro "look" of this panel just look so cool to me when I'm using it. It's downright my favorite LCD on any laptop I own.
 

Powerbook27364

Well-known member
Just tried to submit this and the database crashed for a few minutes! It seems to be back now though...

It comes down to preference, but I'd be bothered by it. If the modern panel was a 1-1 match for the original in terms of looks, I wouldn't be, but the
limitations and retro "look" of this panel just look so cool to me when I'm using it. It's downright my favorite LCD on any laptop I own.
I agree. It will never be 1:1 but hopefully we can find a way to get a close enough panel. I do like the retro feel of the old panel for sure d would miss that but it wouldnt be a hard decision for me at all. Tv versus no tv and I would chose the no tv all day as long as it fits and works.
 

Paralel

Well-known member
Unfortunately for the 540 there is almost certainty no drop-in replacement. 6-bit MTFT LCDs were unusual beasts. 1 and 4-bit panels were far more common. Even the 540c panel is not a true replacement because of the way the CLUT is handled by QuickDraw. You can easily see this in the monitors control panel when you compare the 540 and the 540c. The 540 when the "256 colors/grays" option is selected shows a very smooth grayscale gradient until it gets to a certain point and then the stepping between shades becomes obvious. If you switch the 540c into grayscale mode in the same control panel you will see that the entire distribution of grays is stepped without any smooth gradation. This is because the 540 can display 64 true shades of gray. The 540c panel can only display 27 true shades of gray, and is only speced on paper to handle 32.
 

3lectr1cPPC

Well-known member
That’s why it stinks that mine is damaged in a different way. It’s usable but it doesn’t look very good.
 

Paralel

Well-known member
The images of your screen are greatly appreciated. Another entry for the database. This also strongly confirms exactly what I suspected all along. All the active matrix grayscale panels that Apple used were sourced from Hosiden. It's no coincidence that they all suffer from the same exact problem.

The format, typography, typeface, etc... is literally identical to the identifier on the 540 panels.
 

3lectr1cPPC

Well-known member
Yep, even the portable did. Although it’s never been explainable how portables don’t usually get TV. They can get it, but usually don’t. This is also far from the first time an image of a 170 LCD has been posted, oldcrap.org has a few. The guy who runs that site has a working example of every 100 series PowerBook, all documented! It’s a great resource.
 
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