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Powerbook 180 Screen Tunnelling

N

novastar

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Joined
Mar 4, 2015
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31
Hey guys.

I've acquired a PB180 which unfortunately suffers from the 'tunnel vision' problem. After a few minutes of use, the shadows appear at the edge of the screen growing to leave a visible circle in the center.

I couldn't find much about this via google. I was hoping it would be bad caps somewhere but there is speculation ranging from moisture damage to the LCD to failure of the crystals themselves. Temporary fixes include extreme heat or extreme cold. I don't think it's moisture as the effect is too uniform.

Does anyone have any ideas what the problem might be? I've not opened the screen up yet but I do have a PB170 active matrix screen on hand and there are no obvious components that could fail the PCB (caps etc). Just custom ICs.
 
Had this with every single PB 540 and 170. It seems that all b/w TFT displays are affected. There's no way to fix it, as it's a problem with the layers inside the panel.
 
That's what I feared. It's odd how it appears gradually rather than instantly however and in a very uniform way. If it was a temperature or moisture problem it would surely be more intermittent?

Did you try the freezing method?
 
It's most likely a problem with the glue holding the layers together. The panels were badly sealed (they all seem to come from the same manufacturer) and over time, the glue starts to rot away starting from the edges. When the panel warms up slowly after powering on, polarisation begins to fail where the glue has gone bad.

I have tried fixing some panels using different methods, but to no avail.
 
That's a real shame; This computer is basically junk then and only good for parts :/
 
It's a moisture problem. Some people on 68kmla experimented with "baking" the screens in an oven which at least partially helps improving the condition.

https://68kmla.org/forums/index.php...on-monochrome-active-matrix-powerbooks/page-3

My personal guess is that the only perfect fix would be drying them under heat in a near-vacuum and resealing them which however seems quite unrealistic for a normal household.
 
kyodai said:
It's a moisture problem. Some people on 68kmla experimented with "baking" the screens in an oven which at least partially helps improving the condition.

https://68kmla.org/forums/index.php...on-monochrome-active-matrix-powerbooks/page-3

My personal guess is that the only perfect fix would be drying them under heat in a near-vacuum and resealing them which however seems quite unrealistic for a normal household.
Click to expand...

That thread is hilarious. There's talk of using rice, vacuum cleaners and oven mitts haha :D

I'll give the oven trick a try.
 
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