Tunnel vision on PB170

[Nico]

Not only the powerbook 170 and 180 screens have this but also the Duo 250,280 and Powerbook 540.
It’s a real disaster.

From what I can tell, it‘s not related to usage as I had spare screens of both a pb170 and a duo 250 new in an unopened Apple spare parts box, bought many years ago and guess what : they have the same problem eventhough brand new.

I’m not convinced that the tunnel vison is due to high humidity as my stuff is stored between 45 and 50% relative humidity and temperature between 20 and 25 celcius the whole year.

Some of them are in sealed bags with silica, In have tried heating them as well but nothing solves the problem. At best it offers a temporary solution.
The only solution are brand new made panels. Don’t waist your money on NOS panels.

 

[bwinkel67]

So I think I've solved it for now. I baked the screen at different temperatures with different results. First I tried YouTuber TheBasement's approach and put it in an oven for 10 hours at 185 degrees farentheit. The screen looked good for 15 to 20 minutes and went right back to as bad as it was at the 90 minute mark (so little to no change as my screen starts out good for about that amount of time). I then tried YouTuber i80386sx approach of 4-5 hours at 215-220 degrees farenheit and after 90 minutes the screen hasn't changed. So the key is to get it right at 100 degree celcius mark, or slightly above.

I'm reluctant to attribute it to water, even though the boiling point is at 100 degrees celcius. It may just be that things at that temerature re-bond (re-flow). What was really promising is that i80386sx did an 8-month follow-up video with no change to the screen (btw, he was not working with a PowerBook, but a PC laptop with similar problems). I'm curious to learn how LCD panels are made. Is there a baking process involved? Was I repeating what is done at the factory? If so, would be interesting to find out what temperatures are used.

Other things I learned....I don't think my tapping down the metal tabs idea was sound. The metal tabs are pretty soft so I don't think they would hold out for a long time if tapping them all towards the motherboard would be a fix. The bezel is already pretty tight (when you release one side of the metal tabs, it immediately pops out). So there is likely no gain is holding the LCD more firmly in place. Also, after power down at the 90 minute mark, with the screen not showing any tunnel effects while on, I was able to confirm with the unpowered LCD not showing any signs either (usually you'd see dark spots). It did show a remnant of the menu bar so I don't know if that's normal behavior. It did eventually fade away.

 

[3lectr1c]

Interesting results. My crosspost on 68kmla got some interesting input from the very skilled techknight.
Here's the link: https://68kmla.org/bb/index.php?thr...s-tunnel-vision-problem-testers-needed.41265/

 

[retr01]

vacuum bagging it along with silica pouches for a long, long time

So, putting it in a bag of rice would not "cut it?" I fail to see the difference between silica in a vacuum pouch and a rice bag. And why "long, long time" is necessary? IMHO, a few days should do it.

Can you please explain the significance of using silica in a vacuum pouch left there for several months?

 

[retr01]

What about a 99% IPA bath? 99% IPA will remove water and moisture as it evaporates.

 

[retr01]

4-5 hours at 215-220 degrees farenheit and after 90 minutes the screen hasn't changed.

Isn't that over the storage temperature limit? All electronics have a specific storage temperature limits unless heat-sensitive components are separated and put aside?

 

[bwinkel67]

Interesting video on making of TFT LCD. There is a baking process but that happens after each etched layer. It seems that the sealant is created to keep the liquid crystals contained. So maybe there is a leak between layers? I know there was a YouTuber that was creating their own LCD's at home. I will try and find them and ask some questions.

 

[bwinkel67]

Isn't that over the storage temperature limit? All electronics have a specific storage temperature limits unless heat-sensitive components are separated and put aside?

Well, the electronics aren't included here, only the panel...although in YouTuber i80386sx's approach, his TFT (for a PC laptop) had part of the electronics still attached which he covered with aluminum.

 

[bwinkel67]

What about a 99% IPA bath? 99% IPA will remove water and moisture as it evaporates.

I'm not willing to try that, but if someone has a broken LCD (maybe a crack in it) with tunneling, please give that a try.

 

[retr01]

It seems that the sealant is created to keep the liquid crystals contained. So maybe there is a leak between layers?

If the sealant dries up or is otherwise compromised, moisture gets in.

I know there was a YouTuber that was creating their own LCD's at home. I will try and find them and ask some questions.

Awesome! Can you share a link to that YouTube? I am curious to see how it is done as DIY LCD making at home.

 

[bwinkel67]

If the sealant dries up or is otherwise compromised, moisture gets in.

Oh, so heating could liquify/re-energize the sealing compound...so maybe that's what's going on with baking...

 

[Paolo B]

So, putting it in a bag of rice would not "cut it?" I fail to see the difference between silica in a vacuum pouch and a rice bag. And why "long, long time" is necessary? IMHO, a few days should do it.

Can you please explain the significance of using silica in a vacuum pouch left there for several months?

By the same logic, the issue should have appeared just a few days after production. Instead, it appears some 30+ years later.
Time is surely a huge factor in the equation. Like for everything in life. Clearly there’s some adhesive, sealant, glue layer that irreversibly ages and degrades over time.
So, again (and for last time), my personal experience is the following.
Got this PB170 some 7 or 8 years ago. Severe tunnel vision appearing after just a few minutes. Totally unusable. Got somewhere the hint the issue might be humidity related. It made sense to me, as the explanation is consistent with the pattern: it starts from the edges and it creeps inwards.
Now, as I keep most of my machines (including the PB) in a storage room at my family place - some 1k to 10k km away from where I usually live - the PowerBook remains bagged 364.5 days a year. As minimum. 364.5 x 7 = “long long time”, by my standards. I take it, you may not be ready to give it a try and wait 7 years for the answer.

I keep in the bag a humidity absorbing pouch and gentle vacuum the bag. If I open the bag for playing around with the PB, I replace the pouch with a fresh one.
Now, what I surely noticed - sampling maximum once a year! - is that the tunnel effect has improved. By a lot.
So, first time I could notice some improvement was after minimum one year. Due to Nyquist sampling theorem, I’m not able to tell you if it got better after 6 months or 6 days, though, as I only sample once a year.

Last time I checked, I noticed I could keep the PB on for one hour before it started slightly darkening. Stuff like that. Maybe if I leave it on for 3 hours it will darken totally… I have no idea what kind of use you have in mind, but from my side I have absolutely no use at all, beyond playing some SimCity game or stuff, pretending I’m a teenager again. So one hour on is nice fun, but enough. What happens past that mark, has never been any concern of mine.

Anyhow, good luck with your quest for the magic recipe for reversing time, I will keep on following this thread with great interest.

 

[retr01]

Thank you, @Paolo B, for explaining.

 

[bwinkel67]

By the same logic, the issue should have appeared just a few days after production. Instead, it appears some 30+ years later.
Time is surely a huge factor in the equation. Like for everything in life. Clearly there’s some adhesive, sealant, glue layer that irreversibly ages and degrades over time.
So, again (and for last time), my personal experience is the following.
Got this PB170 some 7 or 8 years ago. Severe tunnel vision appearing after just a few minutes. Totally unusable. Got somewhere the hint the issue might be humidity related. It made sense to me, as the explanation is consistent with the pattern: it starts from the edges and it creeps inwards.
Now, as I keep most of my machines (including the PB) in a storage room at my family place - some 1k to 10k km away from where I usually live - the PowerBook remains bagged 364.5 days a year. As minimum. 364.5 x 7 = “long long time”, by my standards. I take it, you may not be ready to give it a try and wait 7 years for the answer.

I keep in the bag a humidity absorbing pouch and gentle vacuum the bag. If I open the bag for playing around with the PB, I replace the pouch with a fresh one.
Now, what I surely noticed - sampling maximum once a year! - is that the tunnel effect has improved. By a lot.
So, first time I could notice some improvement was after minimum one year. Due to Nyquist sampling theorem, I’m not able to tell you if it got better after 6 months or 6 days, though, as I only sample once a year.

Last time I checked, I noticed I could keep the PB on for one hour before it started slightly darkening. Stuff like that. Maybe if I leave it on for 3 hours it will darken totally… I have no idea what kind of use you have in mind, but from my side I have absolutely no use at all, beyond playing some SimCity game or stuff, pretending I’m a teenager again. So one hour on is nice fun, but enough. What happens past that mark, has never been any concern of mine.

Anyhow, good luck with your quest for the magic recipe for reversing time, I will keep on following this thread with great interest.

No one is suggesting that moisture has nothing to do with it. However, it seems that baking the LCD's isn't juts about driving the moisture out, because 10 hours at 185-190 should have had some impact and it didn't for me. When I then re-tried it at 215-220 it worked, and worked really well -- and YouTuber i80386sx has shown, with that high a temperature it lasted at least 8 months with no change, so if it was just about driving out moisture, you'd think some would have returned. Perhaps the baking is helping rejuvenate the seals so that moisture can no longer get in to start that issue, which would be an improvement of haring to store PowerBook's in vacuum sealed pouches for many years, that's all.

 

[Paolo B]

No one is suggesting that moisture has nothing to do with it. However, it seems that baking the LCD's isn't juts about driving the moisture out, because 10 hours at 185-190 should have had some impact and it didn't for me. When I then re-tried it at 215-220 it worked, and worked really well -- and YouTuber i80386sx has shown, with that high a temperature it lasted at least 8 months with no change, so if it was just about driving out moisture, you'd think some would have returned. Perhaps the baking is helping rejuvenate the seals so that moisture can no longer get in to start that issue, which would be an improvement of haring to store PowerBook's in vacuum sealed pouches for many years, that's all.

Totally agree.

 

[KingDingus]

Baked my screen at 190 for four hours. Will report status when my power supply arrives.

 

[retr01]

I was thinking about this.

What I believe to be a manufacturing defect that Apple clearly should have addressed back then, I wondered why not reseal the LCD? After baking and finding it to work perfectly, reseal, so it does not happen again? Maybe there is no way to do that as the LCD is wholly shut tight.

Any thoughts on that?

 

[bwinkel67]

Baked my screen at 190 for four hours. Will report status when my power supply arrives.

That may not have been enough but curious what you get.

 

[bwinkel67]

So I've been thinking about the screen behavior and the moisture theory. So on mine, before the 212 bake has for now fixed it, my screen would be ok for 15-20 minutes and then start to deteriorate. After an hour it was noticeable on all four corners. After 90 minutes, even more so. I even left it on for 3 hours and it got even worse. However, as soon as you turn the computer off a) you can see the darkened spots on the LCD, and b) it returns to normal in less than an hour. So to me this does not behave like moisture. I mean, are we saying that moisture is being sucked in and then it leaves, or are we saying the moisture is already present. There is no way moisture is leaving as quickly as it enters in a tight space. If the latter, than why is the screen ok for a while at the start and then deteriorate, wouldn't it just stay bad? Also, why does it get back to normal so quickly? That observed behavior follows more of a thermal property of heating and cooling. I could turn my laptop on multiple times in a day and it would always be ok for the first 15 or so minutes (as long as it was off for at least an hour).

So if not moisture, but thermal instead, what is happening? Is it separating at some microscopic level, causing havoc with the liquid crystals and their orientation? That doesn't make sense either. The panel is pretty tightly packed at the top, bottom, and right edges due to the elastomeric strips. It's the left that is open (where the back-light attaches) and even though the crawl seems to always start on the left, it does so at the corners. It's the middle left part that is completely unsupported. You'd think if it is caused by some sort of separation, then you'd get some sort of half-moon dark spot creeping sideways towards the center. So even with thermal, not sure what's going on here. I know with the TRS Pocket Computer 1 screens (see my video above) once they went bad and the LCD started bleeding, they stayed that way 100% of the time, even when off, and didn't get worse with being used (of course they drew a lot less power) It's just weird how these screens reset themselves and somehow thermal heat-increase causes this behavior.

Here is a test I wish I'd done before baking mine to where now it seems fixed. Put the PowerBook in a refrigerator for an hour and see what the screen is like. What would the colder temperature due to the liquid crystal? I forget if they work at 40 farenheit, but if they do, would the tunneling happen or would the screen stay consistent?

Disclaimer, not trying to make anyone feel bad about their theories, just seems to be some misinformation out there and I think it would be helpful to use observation and experimentation and avoid anecdotal evidence which then ends up being all over the place. When I first discovered the tunneling issue and researched it, I was confusing what was out there. I will be very interetsed to see what 4 hours at 190 degrees does for KingDingus -- important caveat, ovens can range 30 degrees in either direction so a temp probe (what I used) is very helpful when baking so you know what the temperature ranges are.

 

[retr01]

So much I read and watch about retr0brite. And now so much about retr0bake.

I agree with @bwinkel67. We need proven information from observation, experimenting, and proving wrong which is the scientific method.

First, it looks like there were manufacturing defects back in the 1990s that affected many Macintosh Powerbooks' LCD screens. Do we have information about that? We could try to find that through libraries online to find the news articles. Maybe some reports out there about that. Second, were the defects in the sealants or what else? Third, what can we do after removing moisture to repair correctly so tunnel vision on LCD screens does not happen again?