Is distorted display due to cable, LCD panel, video driver, or other?

Problem observed:

• Onset of the problem was instantaneous and occurred while I was simply looking at the display, without touching the computer.

• The display shows normal and distorted colors at the same time: in some places bright green exchanged for black, purple for white, etc. Color positions don't change unless a window is opened or the window/menu arrangement changes.

• Windows are continually surrounded by "splash rings," similar to what you see when you open a widget in Dashboard, but frozen in one state.

• Strangely, I can sometimes see the (color-distorted) contents of one window showing through the background of another window that's in front of it, even though those same contents cannot be seen while observing through Screen Sharing.

• Faint "dancing" horizontal lines are barely noticeable in the brighter parts of the display.

• Component colors seem to have their rasters displaced relative to one another, like a color comic strip that was not registered properly when printed.

Screen Image

Note that some text was visually edited out for privacy.

Block Image

Other observations

• Windows, menus, and backgrounds seen through Screen Sharing are all perfectly normal.

• I have not yet tried an external monitor -- hopefully I'll have one set up today.

Steps taken so far

• Reset PRAM -- no change.

• Reset PMU/NVRAM -- no change.

• Booted from separate system on external drive (to detect possible corrupt system color table or other system software problem) -- no change.

• Shined light through Apple logo with the internal backlight lamp turned off. I noticed same color distortion problem (so it seems that the backlight is not the problem).

Suspicions

Having read other trouble reports here related to displays, I suspect that the display cable is the most likely problem, though I am concerned that the problem might actually be with the logic board or other circuitry that drives the display.

Finally, my questions...

• Should I replace the display cable?

• If not, what else should I do, and why?

• If so, what tips might you offer for best success?

Thank you for your time, interest, and help in solving this problem!!

Answer this question I have this problem too

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5 Answers

Most Helpful Answer

First hook it up to an external monitor to try to isolate the problem. If the problem persists, then your video processor has gone south.

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Comments:

Thank you for your very prompt and helpful reply.

I now have an external monitor connected to the Powerbook. That external monitor's display appears to be quite normal, while the problem persists with the Powerbook display.

Am I correct, then, if I presume that this result also points toward the video cable as being the culprit?

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You really can't tell without replacing them. Either the cable or the inverter. Both are reatively inexpensive.

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New observations

While using the ext. monitor, occasionally (esp. after Sleep mode) the PB's screen will suddenly return to normal operation. After 1 to 5 minutes, the problem recurs: once it returned suddenly, another time over a period of 5 sec's.

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Follow-up Qs re parts

Thank you for your advice to replace the G4 Aluminum 15" Display Inverter and the G4 Aluminum 15" 1.5/1.67 GHz Display Data Cable. I will do so.

To be sure that I have the details right, please also help me with the following Qs...

* This Q is to improve my fault isolation skills. The description for the Inverter Card includes, "A bad inverter board can cause a dead backlight." I presume the inverter steps up the voltage for the florescent lamps only. In my earlier tests, I turned the backlight all the way down, shined a light thru the Apple logo, and saw that the display was still distorted. Doesn't that imply that the Inverter is okay, or is there also something else about the Inverter that affects the display behavior?

# Since the Inverter could be one of the causes of the problem, should I consider replacing the G4 Aluminum 15" 1.5/1.67 GHz Inverter & Antenna Cables also?

Many thanks for all your help with this rather strange problem, and for helping me to better understand my Powerbook.

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I'd guess the problem is either the video cable, or the screen itself. The cable's connection to the back of the screen may even just be loose. But you are correct, the inverter's job is simply to provide light, so if the light never goes out, most likely the inverter is not the issue. And you've proven the video chip is not the problem, because it correctly displays the video signal on an external monitor. Again, I'd say the video cable is the first thing to try replacing, and if that doesn't do it, it's probably the screen itself. Obviously the cable is much cheaper and therefore the place to start.

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Hi, I saw this discussion and wanted to contribute. I have fixed quite a few PowerBooks and from what I read here and the things you have tried I would suspect the LCD. Since an external monitor works fine it seems to not be the graphic card. You can get a new LCD fairly cheap and the job is fairly easy (you wrote you already tried changing the display cable and inverter so you are almost there!):

PowerBook G4 Aluminum 15" 1.5-1.67 GHz LCD Replacement

A new LCD is not too expensive, $50-$60 like this one:

http://cgi.ebay.com/Powerbook-G4-A1106-W...

This model is getting some outdated but I have one myself that is in daily use and fills its role :-)

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Thank you very much, asle. Your response appears to give me a practical and economical approach to solving this problem. As a EE, it is frustrating when I must discontinue work on solving a problem due to time and money. That is even more true for devices as well-made and useful as the PowerBook has been. With your suggestion, money is less of an issue, so I'll revisit the trade-off.

As to comments, I (perhaps unnecessarily) had more to say than would fit in a single comment, so I went to the "Answer" format. Next time, I'll split my updates among more than one comment.

Thank you again for your help!

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Sorry, of course the common problem when you have too much text in a comment... You should get points for explaining your case so well :-)

I have seen enough of posts like "my ipod is dead, what du I du"

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+ The drop in price really makes this repair feasible.

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Belated Follow-Up

For numerous reasons, I have not followed up on this issue until now.

Recap

I did replace the Display Data Cable, and saw no improvement. The display still showed…

  1. objects with ripple-like outlines,
  2. mismatched colors — pink where white should be, green where black should be and a spectrum of color distortion in between — as though the system color table was hashed up,
  3. slight noise-like waves and fluctuations throughout all displayed details,
  4. occasional, unpredictable, short-lived moments where the problem cleared completely and everything looked perfectly proper.

All other functional aspects of the Powerbook have remained normal throughout this process, and the display continues to look normal both when using an external monitor and when seen through Screen Sharing and VNC.

Inverter Card Replaced

I replaced the Display Inverter Card, and the problem persisted. I replaced the new card with the old card, and the issue again remained unresolved.

Outlook

At this point, I am inclined to believe that the problem rests in the logic board, but the fact that the external monitor continues to function perfectly with this machine leaves me very uncertain of that possibility. The periodic reversions to normal operation of the display itself signals to me (perhaps incorrectly) that the problem does not reside there.

I love my Powerbook, but without a repair solution clearly evident, I'm at the point where the cost (in time and money) of additional repairs appears to exceed the benefits that would be gained in putting that money toward a new (or refurbished) MacBook Pro. I have a G4 Mac Mini which I can use for "data legacy," so the Powerbook is not essential for that purpose either.

I gratefully welcome your comments and suggestions on this matter, but without those I will have to mark this problem as unsolved, and move on to other projects.

My sincere thanks go to all who have shown interest in this issue and shared there helpful thoughts and ideas.

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Hi ptoll, you should have just edited or commented your first question and not made a new answer like this. Just to keep things ordered here. I got a lot of comments on that before I understood why. Just helping out :-)

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I have the same display issue with my Macbook Pro 3.1 (mid 2007), 2.4 Ghz, A1226, 15.4 " display

The color changes intermittently as you described. I have connected to the external monitor the picture seems perfect.

Can anyone suggest where the problem persist?

Should I need to replace LCD or only the Lcd cable?

It appears the motherboard or the GPU is ok as the external monitor is fine.

Backlighting problem is also cannot be as the internal display is bright when it works normal, so power inverter is working fine I presume.

Need to check the LCD display cable

Also, can it be due to software problem or a RAM problem, as I upgraded my OS from 10.5 to 10.6.3 leopard and Ram was increase to 4Gb from 2GB.

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I have the same display issue with my Macbook Pro 3.1 (mid 2007), 2.4 Ghz, A1226, 15.4 " display

The color changes intermittently as you described. I have connected to the external monitor the picture seems perfect.

Can anyone suggest where the problem persist?

Should I need to replace LCD or only the Lcd cable?

It appears the motherboard or the GPU is ok as the external monitor is fine.

Backlighting problem is also cannot be as the internal display is bright when it works normal, so power inverter is working fine I presume.

Need to check the LCD display cable

Also, can it be due to software problem or a RAM problem, as I upgraded my OS from 10.5 to 10.6.3 leopard and Ram was increase to 4Gb from 2GB.

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ptoll will be eternally grateful.
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