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PowerBook G4 15” display issue

TimHD

Well-known member
I recently powered up my 15” Aluminium PowerBook G4 after some months and noticed the display did not fully come up on boot. The screen shows a faint line across the screen about 1 Inch up from the bottom (not a single pixel, but almost a full charcter height, very faint dark grey band on black screen). I have tried flashlight on the screen but cant see any images. Is this likely to be a broken display cable or is the monitor itself at fault.
Note: Using an external DVI display it was fine - so the video card appears to be fine.
 

Byrd

Well-known member
That's an unusual fault, any extra lines if you put gentle pressure around the front or back LCD or move the display around on the hinge? I'd say it's time to remove the top lid of the PB and reseat the video cable. If the display is truly hosed, PB 15" seem pretty cheap to obtain for parts in Oz.
 

TimHD

Well-known member
Tried as suggested and a very sketchy screen came back. Very flickery, ghosting, image lines and could see the menu bar pop up at the bottom of the screen - basically a very unstable image. I can detect, but don’t seem to be able to project/mirror onto the 23” ADC Cinema Display I was using as backup 2nd screen (worked ok with the 20” ADC Cinema Display earlier?). Moving the monitor back and forward didnt seem to change things while it was running, so it might be somewhere inside there screen or body where something is awry… What’s the easiest way to reseat the cable - via the keyboard or is it in the screen part (not that’s an easy access either)….
 

TimHD

Well-known member
These are examples of the artefacts and lines I am getting on my screen. Any ideas what the culprit might be before I buy a replacement part?FB9EB2AF-0A87-466C-9D10-ED7E47219935.jpeg
F550524C-FB09-4917-98C7-AD216F1A8B60.jpeg
 

LCARS

Well-known member
This might help. iFixIt guides have been useful in the past. That looks like a corrupted signal/grounding issue. Its fortunate that its not the card; that's how my 15" G4 went out.
 

TimHD

Well-known member
This might help. iFixIt guides have been useful in the past. That looks like a corrupted signal/grounding issue. Its fortunate that its not the card; that's how my 15" G4 went out.
So, are you thinking it’s possibly just the display cable being at fault (i.e. either I need to remove the top case, pull out and reconnect the Display Data cable (or look for some damage in the wiring that goes out from the LCD/top lid an through the hinge into the main body of the laptop). Ta
 

LCARS

Well-known member
While I'm not expert if the image didn't change when you were moving the display, it makes me think that the Display Data cable might be damaged/loose. An idea is to identify where the cable is and tap that area with the PowerBook on to see if that changes the situation.

Its odd that it happened while the computer was stored. That would suggest a board problem (if the machine was simply sitting and had no earlier symptoms). While not in English, this will give you an idea of where things are. If you do take the board out, it might be worth a look at the GPU to see if there any obvious signs of shorting or cap failure.

The board in my 15" Retina MPB dislodged enough for the GPU to come into contact with the aluminum case when it heated up. It was intermittent but if I tapped in the area of the GPU, it would change the display problem, which in my case wasn't quite the same but was an indication that it was a physical issue.
 

TimHD

Well-known member
While I'm not expert if the image didn't change when you were moving the display, it makes me think that the Display Data cable might be damaged/loose. An idea is to identify where the cable is and tap that area with the PowerBook on to see if that changes the situation.
Thanks again. I tried tapping/pushing around where the data cable joins the LCD in the top cover/display (having worked out where the connector was inside the top cover from IFixit) but it didn’t seem to change things too much...

As noted earlier, moving the screen back/forward doesn’t seem to change anything at all, suggesting the problem is NOT in the cable at the hinge connection at least, but NOT ruling out that its somewhere else along the cable or at the connecting point in the display.

I removed the top case and could see that the data cable seemed to be connected fine (I didn’t remove / reseat it, but might give that a go just in case something’s oxidised and needs to be connected/reconnected to get things working properly). Failing that, I might have to get a replacement 15” display (or cheap, for parts 15”) as suggested by @Byrd earlier.
 
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