Bad backlight, and I know it's not the screen or inverter

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iBook G3 12"

Model M6497 or A1005 / 500, 600, 700, 800, or 900 MHz G3 processor

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rdklinc @rdklinc

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发帖于: 2010年2月7日

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Bad backlight, and I know it's not the screen or inverter

Hello! I've got piles of 12" iBook G3 800MHZ laptops that have the same issue, which is basically that the backlight is dead. I can see a faint image on the screen. I have tried replacing the entire screen assembly (hinge, screen, inverter cable, video cable) with multiple known-good ones, so I know that the issue is not with any of those components. This is also not the typical G3 video issue, which usually involves freaky random video issues, and that is temporarily resolved with pressure to the left of the trackpad...what's going on here is that the laptop is functional, but that there is simply no backlight. External video does NOT produce an image, which tells me the video chip probably has an issue. I've done all the normal stuff, i.e. remove extraneous components and RAM, reset PMU/PRAM/etc.

Anyway, I think I've probably solved my own problem (bad video chip, which means a bad board) and I just don't like the answer, but does anyone have additional ideas or things to try?

Thanks!

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Chris Green @chrisgreen

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There are means of actually rebonding the solder of the GPU chip, When i repaired a friend's PS3 i used a heat gun over the Cell Processor, and GPU, and that basicly remelts, the solder, and gives it a new contact, without damaging the chip or board.

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Hi Chris! Thanks for the post. I'm familiar with the blowtorch technique, and I've done it on a lot of machines, but it really only works on the more typical video issue that causes the screen to go out completely (not just the backlight, but the video image too), and that can be resolved temporarily by clamping the space to the left of the trackpad (which re-connects the solder points and makes the video come back on). These machines I have now, like I mention, are 100% stable aside from the backlight issue, and do not respond to pressure, and so the rebonding solution does not work for them, unfortunately. I think most likely I've just got some bad boards, but I was curious if someone had a magic wand or similar fix that I could try.

由 rdklinc 完成的 2010年2月7日

rdklinc, you get absolutly nothing on the external monitor cause it seems to be a logic board inverter circuitry issue if you do have video on the internal video port, not a graphic chip issue.

由 lemerise 完成的 2010年2月7日

Lemerise, so the inverter hardware on the board is dead, causing no external video and no backlight on the laptop screen? I'm assuming this is fatal. It's too bad it seems to be a common issue, I have about 20 of these. Thanks!

由 rdklinc 完成的 2010年2月8日

No rdklinc, I can't confirm it's a logic board inverter circuitry failure cause you don't have video on the external monitor. With the logic board inverter circuitry problem you should have video on the external but if it's a graphic chip failure you should not have a stable video feed on the internal monitor. This is a unusual problem. I had many faulty iBook G3 boards but never dealt with this kind of failure.

由 lemerise 完成的 2010年2月8日

Interesting, I wonder if I have a bad batch of machines. Just out of curiosity, in the case of the logic board inverter circuitry issue is there a fix, or does it basically mean the board is bad?

由 rdklinc 完成的 2010年2月8日

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Hi Chris! Thanks for the post. I'm familiar with the blowtorch technique, and I've done it on a lot of machines, but it really only works on the more typical video issue that causes the screen to go out completely (not just the backlight, but the video image too), and that can be resolved temporarily by clamping the space to the left of the trackpad (which re-connects the solder points and makes the video come back on). These machines I have now, like I mention, are 100% stable aside from the backlight issue, and do not respond to pressure, and so the rebonding solution does not work for them, unfortunately. I think most likely I've just got some bad boards, but I was curious if someone had a magic wand or similar fix that I could try. — rdklinc
rdklinc, you get absolutly nothing on the external monitor cause it seems to be a logic board inverter circuitry issue if you do have video on the internal video port, not a graphic chip issue. — lemerise
Lemerise, so the inverter hardware on the board is dead, causing no external video and no backlight on the laptop screen? I'm assuming this is fatal. It's too bad it seems to be a common issue, I have about 20 of these. Thanks! — rdklinc
No rdklinc, I can't confirm it's a logic board inverter circuitry failure cause you don't have video on the external monitor. With the logic board inverter circuitry problem you should have video on the external but if it's a graphic chip failure you should not have a stable video feed on the internal monitor. This is a unusual problem. I had many faulty iBook G3 boards but never dealt with this kind of failure. — lemerise
Interesting, I wonder if I have a bad batch of machines. Just out of curiosity, in the case of the logic board inverter circuitry issue is there a fix, or does it basically mean the board is bad? — rdklinc

iBook G3 12"

Bad backlight, and I know it's not the screen or inverter

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