180 (and other lcd, I gues) reassembly

[christie]

So today I decided to try baking an lcd on a parts PowerBook 180 I have.

Used the "warm" setting of 175 for 4 hours. I did not bake it with the circuit board. I straightened the bent tabs fastening the glass sandwich to the backlight and circuit board.

After a decent cool down period I reassembled and tested the lcd. As I feared, lots of vertical black lines and a white ghost outline of the mouse pointer and question mark disk icon.

I took it apart again, tried again and similar but different pattern wise results.

Before the third time I noticed that there are cross hairs on the circuit board and tiny square etched on one of the glass layers. I figured that they are alignment witness marks and did my best to line everything up and ...

Same same. Probably better but not right.

Has anyone successfuly reassembled their active matrix display? Everything draw okay? How did you line everything up right? Are those witness marks?

I understand that I could have baked it attached to the circuit board, but if it was a really successfull bake, I'd want to be able to reseal the glass edges and for that it HAS to come off the board.

Thanks!

 

[techknight]

I cant remember how a PB180 LCD is put together, but its possible that it uses the rubber style Zebra stripe like the Portable? If so, then you need to clean the mating surfaces really really good with alcohol or some other solvent to get the oxides off, or it wont work right. 

 

[christie]

Yep, zebra stripe elastomeric strips.

Using denatured right now.

Hope it gets right before those metal tabs snap from bending fatigue. Also because even though the data is jumbly, optically the screen is a million times better after the four hour bake, even in the corners. The tunneling was quite bad on this guy.

In the future I think the zebra should be cleaned before the bake. Any impurities that were there just got toasted on in the oven...

 

[christie]

Well,

After several times trying to clean and reassemble, the display is still drawing patterns of horizontal and vertical lines.

Some other technique aside from cleaning the zebra stripe with alcohol and refastening the panel to board needs to happen. While this particular panel was a test article from a parts machine, it's frustrating long term. It suggests that after using any of the desiccation methods to clear tunnel-vision, re-sealing the glass edges is not a real possibility.

Any ideas?

 

[techknight]

Unless it was killed via static electricity from poor handling, or the heat from the oven. There could be a small crack in the glass severing a bunch of connections. 

Without a picture of the issue its hard to say. 

I have taken apart and put together portable LCDs without issue. you GOTTA be careful. 

 

[christie]

Here are photos from three different attempts at reassembly.

 

[techknight]

Thats definitely the zebras. 

Hopefully you peeled them away from the PCB only and not the glass. IF you peeled them from the glass and the PCB, you likely lost the alignment. Zebra stripes also need aligned as well as a shit load of pressure... 

 

[christie]

Thanks.

They stayed attached to the glass through the whole process, only came off the PCB.

So, what now?

 

[techknight]

press on the LCD frame or grab an insulated plastic clamp to see if it goes away when you clamp the metal harder. You may not have it tight enough. 

If that doesnt work, then chalk it up to experimentation and move on. 

 

[avadondragon]

I did this to a IBM PC Convertible that I was attempting a EL panel backlight mod on.  In my case I ended up breaking a couple of the retention clips on the metal bracket.  I keep thinking I will machine a new metal piece but have never gotten around to it.  Probably never will sadly.  I think I might have disturbed the alignment on one of the zebras too.  Half of the screen is beautiful and perfect and everything I was hoping for when I started the project.  The other half looks like garbage.

 

[techknight]

yeap, you have to be VERY careful. Luckily I havent broken anything... Yet.... There is always Yet.... 

 

[christie]

Yep, I think I'll try clamping tomorrow. I've got nothing good to lose and maybe something to learn from this display at this point...