Non backlit Mac portable: LCD lines

[pinto_guy]

So I just revived a Mac portable (non backlit), and now have it boot up from an external HDD. I bought it off CL for $50, and following great advice from this forum, I recapped the board, recelled the battery. I also had to change one of the power FET that had died.  So everything worked as planned. Only the HDD decided that it was dead, and reading some of the posts here, I wasn't very surprised.

There is just one more detail that I need to fix, and could not find a solution here. My LCD screen shows a couple of horizontal lines. These lines are "on" or white, and dot not turn off (go black). One line is actually a line and a half, with only half the second line being "dead".

So my question is the following: is it something that can be fixed ? Does it have to do with the video memory, the LCD itself, bad contacts ?

Thanks in advance. Once I have this fixed, my next job will be to change or fix the HDD.

Thanks !

 

[khannonnd]

So I just revived a Mac portable (non backlit), and now have it boot up from an external HDD. I bought it off CL for $50, and following great advice from this forum, I recapped the board, recelled the battery. I also had to change one of the power FET that had died.  So everything worked as planned. Only the HDD decided that it was dead, and reading some of the posts here, I wasn't very surprised.

There is just one more detail that I need to fix, and could not find a solution here. My LCD screen shows a couple of horizontal lines. These lines are "on" or white, and dot not turn off (go black). One line is actually a line and a half, with only half the second line being "dead".

So my question is the following: is it something that can be fixed ? Does it have to do with the video memory, the LCD itself, bad contacts ?

Thanks in advance. Once I have this fixed, my next job will be to change or fix the HDD.

Thanks !

My Portable had the same issue with the screen after I got it recapped, etc.  I was lucky enough to find a sealed NOS LCD service part that I replaced it with, and it worked fine, so I would wager the problem is the LCD itself.

I seem to recall Techknight saying cleaning the LCD contacts could help fix it, but I don't recall.

 

[aplmak]

It could very well be the LCD display cable.. I've seen them personally do that... There is a way to pull apart the display.. You insert (a paperclip bent straight) into the side holes and slide down (top down) and the cover lifts off.. 

 

[aplmak]

There are cables I think on ebay for sale.. It may be the LCD but I would start with the cable... (I also may have one for you)

 

[CelGen]

Dead lines are typically indication that a bonded joint somewhere between the LCD and the panel's LCD controller chip has failed. It can do this either with age or rough handling. The joints typically cannot be repaired but with later color LCD screens I usually felt around the assembly and cables while it was on and if I found a spot where pressing on it removed or reduced the lines I shimmed something like some pieces of paper in between the point and the nearest solid surface.

 

[pinto_guy]

Thanks everyone. For what it's worth, I inadvertently dropped the computer last week-end (fortunately on the carpeted floor so nothing broke), and the line pattern changed a bit. This would tend to incriminate the contacts.

I'll report next week after I have a chance to look into it some more.

 

[techknight]

the portable LCD uses rubber zebra-stripe carbon composition inserts that connect the LCD Glass itself to the rear PCB. Removing the LCD glass, cleaning the contacts, and reinstalling/twisting the LCD frame back together should fix it. Only other option is replacing the zebra stripe material, which can be found. 

 

[pinto_guy]

OK so I finally got to it this week-end.

I detached the PCB from the LCD glass, and cleaned the zebra stripes all the way around (see photo 1). Upon reassembly, I noticed that I had to add small pieces of spacer material (I used clear blister packaging pieces) in order to keep the contacts tight.

However, the lines were still there at the same spot. I then decided to try to clean the contact between the zebra strip and the glass. However, I could not fully remove the stripe from the glass. I could lift it toward to edge of the frame, but not fully remove. So I attempted to clean underneath there by inserting an IPA soaked Q tip between the stripe and the glass. After reassembly, I had a completely new set of lines, telling me that it is the right problem to go after (photo 2). But unless I completely remove the stripe, it would be hard to fully clean.

Techknight, you hinted that it is possible to remove this stripe, and even change it. Would you care to give some detail on this ? Thanks

 

[techknight]

it peels off. its stuck on there with a slight bit of adhesive. 

You can purchase zebra stripe stuff on ebay. 

this is a very very common failure. especially in multimeters. 

Also when you anchor the LCD back together, those tabs have to be super tight before twisting back into place. OR this will happen. 

 

[pinto_guy]

Update today: I could remove the glass assembly from the metal frame (pushed gently on glass with toothpick through corner holes) , and slowly removed the zebra strip all the way around. Now I have the LCD glass just by itself. I cleaned all the way around. But using a magnifying glass, I noticed that a few tiny black connection lines etched into the glass have become open, or broken. I'm afraid there is not much I could do about this unfortunately.

I would welcome anyone who would have a spare LCD (non backlit) to sell. Please send PM if you do. Thanks

 

[gsteemso]

Back in the ancient history of cars with resistive-heated electric rear-window defrosters, say the 1970s through the 1990s, you could cheaply buy little bottles of goop from any auto parts store which were basically conductive paint.

In those days the heating element was just printed onto the interior surface of the window, rather than being inaccessibly sandwiched between the layers of the safety glass. Thus, whenever you scrubbed, wiped, bumped against, or (it seemed) coughed gently while walking past on the opposite side of the street from such a window, the heating element would acquire a microscopic crack or scratch that would act as a cut circuit trace, and a thin stripe across your window would thereafter refuse to ever be defogged. The fix was to dab a little of the aforementioned cheap conductive paint onto the break.

I don’t know whether that conductive car-window paint is still widely and cheaply available, nor whether something similar was ever produced for this sort of more delicate work, but either way, the repair of broken conductive traces on glass is a very well-known problem, and you should be able to buy or make some suitable repair compound without too much trouble.

I realize this is all moot if a replacement LCD panel should turn up at an acceptable price, but the supply of those is finite, so at some point one of our future comrades will be needing to find this post in the archives.

 

[CC_333]

I thought cars still used the resistive heating element-type rear defrosters? Our new 2014 car has it still??

I mean, at least it *looks* like it does?

c

 

[pinto_guy]

gsteemso: thanks. Can you say a bit more about how to fix those electric traces ? Would you use one of these conductive glue pens ? Would they be making lines that would be thin enough for this screen ?

 

[flecom]

they are still a thing

https://www.google.com/search?q=conductive+pen&ie=utf-8&oe=utf-8

used to use them back in the day for overclocking AMD Athlon chips

 

[gsteemso]

Yes they still use resistive defrosters. The modern ones have the traces between the layers of glass where they can’t get damaged though. As to the repair method, by the time I was old enough to have a car with a rear defroster, it was of the newer type; I have never actually needed to carry out such a repair and do not know anything about it, beyond that it is possible and was at one time a fairly routine operation. Sorry I can’t be more help.

 

[CC_333]

Our older car from 2006 has the "traces" printed on the inside surface (one of which is actually broken; I should fix it). Did the "traces between the layers of glass" thing happen sometime recently, like in the last 5 or so years? Also, since when is the rear glass dual-layer? I thought that was only for the windshield, and the rest of the windows were made of single-pane safety glass?

Incidentally, I think some sedans/two-doors have sometimes actually had an air duct from the front climate control system that blows air at the rear window instead of a heating element printed on the glass, like the front defrosters. Is this true, or am I imagining things?

c

 

[trag]

Two part conductive epoxy is also available for PCB repair and similar. It can be tough to work with. I would practice making hair thin lines on some other glass first, I think.

 

[gsteemso]

CC_333, I was unaware that windows with exposed heating traces were still a thing in new vehicles. I stand corrected. As to the possibility of dual-layer manufacture, you are probably right about it not being done that way; for all I know, they just stuck a layer of plastic over the traces on the windows I have seen. It's not like I have ever examined one very closely.

 

[Sideburn]

it peels off. its stuck on there with a slight bit of adhesive.

You can purchase zebra stripe stuff on ebay.

this is a very very common failure. especially in multimeters.

Also when you anchor the LCD back together, those tabs have to be super tight before twisting back into place. OR this will happen.

I’m about to make an attempt at fixing the same issue. First I had one white horizontal line and now I have two. I’m assuming it is the zebra strip issue. Do I clean the contacts on the glass and PCB with isopropyl ? I was going to order some zebra strip just incase from this guy on eBay: https://www.ebay.com/itm/1726576645...ar=474552949816&widget_ver=artemis&media=COPY

But I don’t know how many strips and what dimensions until I get in there. Do you happen to know so I can order now and get them on the way?

I’m currently repairing another logic board so I will have two that I can use to rule out the main board as being the issue.

 

[jshardin]

I’m about to make an attempt at fixing the same issue. First I had one white horizontal line and now I have two. I’m assuming it is the zebra strip issue. Do I clean the contacts on the glass and PCB with isopropyl ? I was going to order some zebra strip just incase from this guy on eBay: https://www.ebay.com/itm/1726576645...ar=474552949816&widget_ver=artemis&media=COPY

But I don’t know how many strips and what dimensions until I get in there. Do you happen to know so I can order now and get them on the way?

I’m currently repairing another logic board so I will have two that I can use to rule out the main board as being the issue.

Hi there, did you ever get this to work?