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Compaq Portable 486/66 screen issues

hagelaars

hagelaars

Member
Joined
Jun 27, 2016
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48
Location
The Netherlands
Just bought a Compaq Portable 486/66 with a monochrome screen. The computer looks perfect, and so all the hardware inside. Even 32MB of RAM. I took it over from the first owner, he said he hadn't started the computer up anymore for 20 years. I even found the original software on the harddisk, all files installed in 1995!

So today I started it up after so many years. Off course the diagnostics had to be set again. But the main issue is the screen. I noticed the screen has damage. A vertical white line is noticeable at the right side. That's not the biggest issue. The screen is grainy with distortion and flickering (see video). Is there a solution to get the screen better? Can it be caused by leak capacitors or is there another solution? I hope anybody can help. Thanks in advance.

 
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The vertical line is most likely a problem with the LCD itself. The edge connections inside the display are failing and the fix is to replace the screen. You might get lucky and be able to press on the connection and make a good enough contact that will for a short period of time "repair" the problem, but it will return.
 
I too would just upgrade the display in all honesty. The monochrome DSTN wasn't the greatest when new. If you can figure out the dimensions of the original panel, I'm sure we can figure you out a suitable replacement on the cheap. Going to guess its a 12.1"?
 
Lines aren’t always easy to fix depending on the issue. It’s generally something with the connections inside the LCD itself.

The issue with the color models looking washed out or turning white is capacitors in the LCD itself. The Toshiba T3200SXC and early ThinkPads are known for this as well.

The monochrome and color displays on these were both active matrix.
 
Al Kossow said:
My sympathies. I've thrown out dozens of them (Monochrome and especially color) because their screens are crap.
You will find many threads on here with people trying and failing to save them.
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You really throwed them away? Recently or by then? These computers are hard to find, especially in Europe. Therefore they are expensive, even with a broken screen.

ajacocks said:
There's also a direct replacement for the screen that has been done:


- Alex
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Yes, I noticed that thread. But it seems too technical for me.

DeltaDon said:
The vertical line is most likely a problem with the LCD itself. The edge connections inside the display are failing and the fix is to replace the screen. You might get lucky and be able to press on the connection and make a good enough contact that will for a short period of time "repair" the problem, but it will return.
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I'm also affraid the screen can't be repaired anymore. Thanks for the study on this.

twolazy said:
I too would just upgrade the display in all honesty. The monochrome DSTN wasn't the greatest when new. If you can figure out the dimensions of the original panel, I'm sure we can figure you out a suitable replacement on the cheap. Going to guess its a 12.1"?
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Yes, thanks. I think it has to become replacement. But to replace it with another brand/sort screen..? I have some doubt if I will manage.

compaqportableplus said:
Lines aren’t always easy to fix depending on the issue. It’s generally something with the connections inside the LCD itself.

The issue with the color models looking washed out or turning white is capacitors in the LCD itself. The Toshiba T3200SXC and early ThinkPads are known for this as well.

The monochrome and color displays on these were both active matrix.
Click to expand...
Also thanks for your answer. I's clear that the screen has to be replaced instead of repairing i'm afraid..
 
By coincidence, I managed to get another Compaq Portable 486(c!) (so colour screen). The casing is in very bad condition, but the computer itself seems working, except the screen. I tought: maybe I can replace the monochrome with this screen.. if it's worth a try for repair?
The screen stays black, only with some white glow at the bottom of the screen (see photo). Is this a completely 'dead' screen, or worth a try to fix?

IMG_0497.jpeg
 
A black screen may have a bad inverter or bad back light bulb. Not the same as a LCD with lines going through it. Shine a light on the screen and see if you can see a faint sign on screen. These LCD shine light through the actual liquid crystal and back light the output so you can see it. No back light no visible display.
 
DeltaDon said:
A black screen may have a bad inverter or bad back light bulb. Not the same as a LCD with lines going through it. Shine a light on the screen and see if you can see a faint sign on screen. These LCD shine light through the actual liquid crystal and back light the output so you can see it. No back light no visible display.
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Thank you! You brought me to the right idea because of this. I disassembled the screen and found that one tube isn't working anymore (see picture below). I changed the tube that's working on top, to see if the screen is still working (when you start up, most of the text is displayed on top of the screen instead of the bottom). Now I see a blinking cursor at startup! I couln't try the display further, because the Compaq Portable with this screen, seems to do nothing than only display a blinking cursor... (maybe because of an EISA reset?). To try the screen, I have to put it on my other CP (the one that has now the monochrome screen). If it works in a good way, I have to find a good second tube. They seem some specific for this screen.. maybe there is another solution with a led strip or something. If somebody knows where you can order those tubes or another solution, please let me know. Thanks in advance!

IMG_0504.jpeg
 
Does anybody know more specs about the tubes? (like needed voltage and light strength). Hope anyone knows, otherwise I have to measure myself.. I'm thinking about simulating the tubes with led strips..
 
Changing the tube in some LCD's can be a major job since they weren't designed to allow changing the tubes at easy and require nearly disassembling the whole beast to get the tube out. PITA. Other's have a simple cover or two removal to get at the tube. Make sure to insulate the new contacts to match the original set up since the voltage will be in the 1,000 volt level and arcing will cause more issues.
 
DeltaDon said:
Changing the tube in some LCD's can be a major job since they weren't designed to allow changing the tubes at easy and require nearly disassembling the whole beast to get the tube out. PITA. Other's have a simple cover or two removal to get at the tube. Make sure to insulate the new contacts to match the original set up since the voltage will be in the 1,000 volt level and arcing will cause more issues.
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Thanks for your reply. Replacing seems not that difficult, the tubes can be reached easily. I will take care of the voltage rates. But for now I reached another problem that I have to fix first.. (see my other thread).
 
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hagelaars said:
Thanks for your reply. Replacing seems not that difficult, the tubes can be reached easily. I will take care of the voltage rates. But for now I reached another problem that I have to fix first.. (see my other thread).
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Hey did you ever figure out which bulbs to use, I have the same issue, here's some pics, mine blew out rather catastrophically, burning a hole in the end, and turning the glass brittle.
 

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I found them on Amazon, they're the exact same size, maybe a tad smaller, but not enough to do anything bad. I measured 10 in long, but these are 9.8in long which is close enough

Screenshot_20250116-190247.png
 
No, I can probably calc that though P = V x I, just have to measure the current and voltage(P is power in watts, and I is current in amperes for those reading this in the future, and those who don't know.). I think the wattage only has to do with how much power it draws, and these probably draw less than the ones in the 486c of I had to guess.

I'm so glad I'm taking a physics class right now.

If anyone's more knowledgeable, let me know if I'm wrong. I do know that bulb wattage doesn't necessarily mean the amount of power it draws, but more commonly refers to the brightness. It came from marketing light bulbs, where it's just easier to say for ex. This is a "60w bulb" versus "this is the same brightness as a conventional 60w bulb."
 
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