Sorry for the long post, but I needed to explain what I had done in order for my questions to make any sense. Note this this is just a record of what I did for the purpose of explaining my questions at the end of the post.
I recently came into possession of a couple of Powerbooks and started working on refurbishing them. The Powerbook 180 had a tunnel vision problem with the lcd screen as can be seen in the picture below (condition at 41 minutes after startup):
I decided to try to fix the tunnel vision issue and read some articles on the internet about potential causes. I found two potential fixes so I decided to try them in order of difficulty. First, I tried placing the lcd in a closed container with desiccants for ten days to see if that had any impact on the lcd tunnel vision. The picture below shows the laptop and lcd in a dry box with a humidity of 15% where it remained for ten days:
Unfortunately, after those ten days, I saw no real change in the lcd as shown in the picture below (condition at 45 minutes after startup):
Next, I decided to try baking the lcd as I had heard that baking could possibly help with tunnel vision. I removed the lcd from the laptop. Note that the half of the metal tabs twist clock-wise and half twist counter-clock-wise for removal. Then I setup an old toaster oven that I had (I didn't want to use an oven that would ever again be used for food in the future as I didn't want to risk contaminating it.) Below is a picture of the toaster oven with tray and parchment paper:
I ran a test with the toaster oven without the lcd to see how stable the temperatures would be. The lowest temperature setting for the toaster oven was 200F. I used a wired digital grilling thermometer to measure temperatures during the test. When the oven was set to 200F, the temperatures varied from 185F to 197F sinusoidally over a ~10 minute period. In order to stabilize the temperatures somewhat and prevent localized hot spots on the lcd, I placed the lcd on a sheet of parchment paper on a tray, then I placed another sheet of parchment paper on top of the lcd (neither sheet of paper touching the lcd screen.) By placing the paper on top and below the lcd, it created a pocket of air between the sheets where the temperature was stabilized to roughly 191F +/- 3F with a ten minute period. Below is a picture of the lcd and parchment paper in the tray:
Note that weights were necessary to keep the top sheet from being blown around during oven operation. I ran the oven for 5 hours with this setup (lcd experiencing 191F +/- 3F with a ~10 minute period.) The oven wasn't designed to operate for this length of time even at the lowest temperature so the exterior got hot, and I burnt my finger. After that, I allowed the oven and lcd to cool to room temperature naturally with the oven off and power unplugged.
After the lcd and oven reached room temperature, I reinstalled the lcd in the laptop so I could see if there was any improvement. Note that as I mentioned before that half of the tabs twist clock-wise and half twist counter-clock-wise so there wasn't much / any slop in the positioning of the lcd during installation. Once everything was reconnected, I turned on the laptop and discovered that there was significant improvement. Below is a picture of the laptop lcd after 42 minutes of operation:
Oddly, the lcd continued to improve over the approximately 3 to 4 days after baking despite just siting in the laptop not being used. In the end, this is what the laptop lcd looked like after those 3 to 4 days (note that the interference pattern is not visible to the eye - not sure why the camera shows that):
Note that this picture is after an hour of operation.
Finally, here are my questions for others that have done a similar repair on their 180 lcds:
1. Do you think that the ten days in the dry box improved the effectiveness of the oven baking? Moisture removal, etc?
2. Or was the problem actually that the adhesive between layers needed to be reflowed, and the time in the dry box did nothing at all?
3. Why did the lcd continue to improve over the 3 to 4 days after removal from the oven?
4. After the baking of the lcd, I have noticed a faint ghosting of windows that have been displayed for 40 to 60 minutes on a dark background. Is this due to the baking of the lcd or is this just the nature of some of the early active matrix displays? Barely noticeable in person to be honest and disappears fairly quickly. See the picture below for an example of a ghosted window after being displayed for ~60 minutes on a dark background:
5. Is this typical behavior of an lcd with tunnel vision or is this unique to my Powerbook 180 (sample size of one after all)?
6. Is the problem really moisture or the need to reflow the adhesive between layers?
Before I work on the next Powerbook (which is in awesome shape save the lcd), I want to make sure that I'm not doing something stupid and damaging the lcd beyond repair in the long term. Any guidance or recommendations would be greatly appreciated.
I recently came into possession of a couple of Powerbooks and started working on refurbishing them. The Powerbook 180 had a tunnel vision problem with the lcd screen as can be seen in the picture below (condition at 41 minutes after startup):
I decided to try to fix the tunnel vision issue and read some articles on the internet about potential causes. I found two potential fixes so I decided to try them in order of difficulty. First, I tried placing the lcd in a closed container with desiccants for ten days to see if that had any impact on the lcd tunnel vision. The picture below shows the laptop and lcd in a dry box with a humidity of 15% where it remained for ten days:
Unfortunately, after those ten days, I saw no real change in the lcd as shown in the picture below (condition at 45 minutes after startup):
Next, I decided to try baking the lcd as I had heard that baking could possibly help with tunnel vision. I removed the lcd from the laptop. Note that the half of the metal tabs twist clock-wise and half twist counter-clock-wise for removal. Then I setup an old toaster oven that I had (I didn't want to use an oven that would ever again be used for food in the future as I didn't want to risk contaminating it.) Below is a picture of the toaster oven with tray and parchment paper:
I ran a test with the toaster oven without the lcd to see how stable the temperatures would be. The lowest temperature setting for the toaster oven was 200F. I used a wired digital grilling thermometer to measure temperatures during the test. When the oven was set to 200F, the temperatures varied from 185F to 197F sinusoidally over a ~10 minute period. In order to stabilize the temperatures somewhat and prevent localized hot spots on the lcd, I placed the lcd on a sheet of parchment paper on a tray, then I placed another sheet of parchment paper on top of the lcd (neither sheet of paper touching the lcd screen.) By placing the paper on top and below the lcd, it created a pocket of air between the sheets where the temperature was stabilized to roughly 191F +/- 3F with a ten minute period. Below is a picture of the lcd and parchment paper in the tray:
Note that weights were necessary to keep the top sheet from being blown around during oven operation. I ran the oven for 5 hours with this setup (lcd experiencing 191F +/- 3F with a ~10 minute period.) The oven wasn't designed to operate for this length of time even at the lowest temperature so the exterior got hot, and I burnt my finger. After that, I allowed the oven and lcd to cool to room temperature naturally with the oven off and power unplugged.
After the lcd and oven reached room temperature, I reinstalled the lcd in the laptop so I could see if there was any improvement. Note that as I mentioned before that half of the tabs twist clock-wise and half twist counter-clock-wise so there wasn't much / any slop in the positioning of the lcd during installation. Once everything was reconnected, I turned on the laptop and discovered that there was significant improvement. Below is a picture of the laptop lcd after 42 minutes of operation:
Oddly, the lcd continued to improve over the approximately 3 to 4 days after baking despite just siting in the laptop not being used. In the end, this is what the laptop lcd looked like after those 3 to 4 days (note that the interference pattern is not visible to the eye - not sure why the camera shows that):
Note that this picture is after an hour of operation.
Finally, here are my questions for others that have done a similar repair on their 180 lcds:
1. Do you think that the ten days in the dry box improved the effectiveness of the oven baking? Moisture removal, etc?
2. Or was the problem actually that the adhesive between layers needed to be reflowed, and the time in the dry box did nothing at all?
3. Why did the lcd continue to improve over the 3 to 4 days after removal from the oven?
4. After the baking of the lcd, I have noticed a faint ghosting of windows that have been displayed for 40 to 60 minutes on a dark background. Is this due to the baking of the lcd or is this just the nature of some of the early active matrix displays? Barely noticeable in person to be honest and disappears fairly quickly. See the picture below for an example of a ghosted window after being displayed for ~60 minutes on a dark background:
5. Is this typical behavior of an lcd with tunnel vision or is this unique to my Powerbook 180 (sample size of one after all)?
6. Is the problem really moisture or the need to reflow the adhesive between layers?
Before I work on the next Powerbook (which is in awesome shape save the lcd), I want to make sure that I'm not doing something stupid and damaging the lcd beyond repair in the long term. Any guidance or recommendations would be greatly appreciated.
