Replacing an old NEC 286F backlight with almost no money

[blabsxar]

Hello.

I recently acquired one old defective NEC 286F with lots of problems. Luckily, we could still powering it on, but the first problem we saw is a defective back light. It was yet possible to see text on the screen, but not easily. We needed to fix it in order to view the screen so we could address other problems. Also, we almost didn't have any money to spend on an almost 30yo computer.

I friend of mine, Muriel, a very talented young electronic technician and engineering student came up with this idea: "what if we used a fabric as a kind of 'light sink' and led stripes"?

We did it and it worked! The solution is not perfect (actually, it is much better in live, not in pictures), of course, and we are open to further suggestions, but I would like to post it here anyway to show people that possible solutions don't need to be fancy nor expensive to work.

Defective back light (one side):



Defective backlight (the other side):



Muriel humiliating me with his soldering skills:





Testing (there is a "substripe" failing):



Assembling:





Results:

 

[tingo]

Well done!

 

[Dwight Elvey]

I'm looking at a similar problem with a failed fluorescent tube. The unit has two tubes. One is working and the other not. The tubes don't seem to be easy to find. I'm considering using LEDs. My differences in contrast should be better as there is more distance between the LEDs and the screen.
I wonder how Apple does it on their I-pads. I've had to replace a display and touch screen on one ( not a nice project ). The LEDs are on a strip right next to the top and bottom of the screen. They get a nice uniform light, despite the inverse square law. Maybe they use a tapered density plastic. I should have ripped the display apart before tossing it.
Dwight

 

[MikeS]

Yeah, neat! Could a piece of white plastic from a broken TV diffuse the light a bit?

 

[Chuck(G)]

Dwight, I have a couple of NOS CCFL backlight tubes that I bought for a monitor I no longer own. What size do you need?

 

[Dwight Elvey]

It is in a HP fold out windows portable machine. I'll have to look at it and tell you. I don't recall if I put it in storage or in my garage.
Dwight

 

[Chuck(G)]

Well, for Dwight and whoever else is interested, I measured the CFLs and this is what I have:

3 x 10.5" long 1/4" (approx) diameter
1 x 12" long 1/4" (approx) diameter
2 x 12" long 1/4" (approx)

The 10.5" ones also come with 2 inverters.

I don't recall when I picked these up; they've been sitting on a top shelf for years. PM me if you can use them.