PB G4 - no backlighting

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Tom Owad's picture
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The hinges on my Powerbook G4 have been on their way out for a long time. Today finally, I let the screen drop back and the hinge by the power button snapped and the backlighting went out. (The outermost half-inch section of hinge snapped off from the LCD casing.)

I had a screen from a dead Powerbook, so I took this one out and installed the replacement unit. Unfortunatley, even with the new display I still have no backlighting.

Notably, the new display is missing the blue and white cables, but I'm almost certain this is only for the sleep light. I guess I could try swapping in the inverter board out of the dead unit, but that ons'z in unknoan condition, and I can't imagine how I could have damaged the inverter board by letting the screen drip.

Any thoughts are most appreciated. I really want to get this working again!

Interestingly, here's a fellow with an almost identical problem:
http://torrez.org/archives/2002_12.php

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dankephoto's picture
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dead backlight or dead inverter board . . .

new screen and BL still dead sure smells like a kaput inverter. Keep in mind the inverter supplies the BL tube with a pretty good voltage. It's surely possible the BL cable got shorted as it got ripped from its usual comfy place, killing the inverter in the process.

You are correct about the blue 'n' white cable, it's just the sleep light.

BTW, which model(s) TiBooks do you have (dead and alive?) What was wrong with the 'dead' 'Book? The different series TiBooks use different inverters, so they may be interchangable, or not.

here's my still-unfinished TiBook displays page:
http://mywebpages.comcast.net/macdan/tibook_display.html

Dan K

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Tom Owad's picture
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My original Powerbook is a fi

My original Powerbook is a first generation 500 Mhz model, bought the day they were announced. The parts-unit is a first-generation late-stage prototype. It's in rough shape and with a bad motherboard. The display was believed to be find, though.

Is it possible to get into the displays to replace the backlight?

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dankephoto's picture
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backlight replacement not for faint of heart

It's definitely a 9 or 9.5 on the 1-10 difficulty scale. Again, see my page:

http://mywebpages.comcast.net/macdan/tibook_display.html

for some display takeapart infos.

Removing the LCD from its bezel without buggering anything up is one thing, but then digging out the BL lamp is another project in itself. I disassembled a cracked LCD and even though I tried to be careful I still made a hash of the thing. Good thing the LCD was already cracked, else I'd have been a bit peeved about the results. Smile

I did get the (very delicate) BL lamp out without breaking it, but the LCD structure got a bit messed up. I expect that's sort of the opposite of what you would want.

My advice still is to try another inverter before even thinking about opening a display. eBay prices for inverters are very reasonable. Be aware the inverter board is unique to the 400/500 series (Apple's SS doc shows pn 922-4601.)

Dan K

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Tom Owad's picture
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Half way there...

I replaced the inverter board (and jostled all sorts of stuff). Now, when I first power up or wake up from sleep, the backlight comes on for about 1 second, then goes off.

I think I saw some mention of conditions like this in my last Google search, so I'll be re-Googling. If anybody know how to fix this, speak up!

Thanks again for the advice.

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Tom Owad's picture
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Crimped cable!

Turns out I got the cable pinched in the hinge when I installed the replacement inverter board. Got that worked out and the (replacement) display looks as good as new!

The only question now is where all these extra screw came from... Wink

Thanks!

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dankephoto's picture
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so the original inverter was NG?

Just wanted to add this data point to my own knowledge base.

Just so's I got this here story straight, what's working now is the replacement LCD and inverter? The original inverter is the culprit?

You figger the breaking hinge killed the inverter board? Is there any visible damage to the old screen's BL cable?

I'm sure you already know, but if my understanding is correct, this of course means your original LCD is probably still usable (or at the very least fixable.) Laughing out loud

Dan K

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Tom Owad's picture
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[quote]Just so’s I got this

Quote:

Just so’s I got this here story straight, what’s working now is the replacement LCD and inverter? The original inverter is the culprit?

That's the way it's looking.

Quote:

You figger the breaking hinge killed the inverter board? Is there any visible damage to the old screen’s BL cable?

The pink cable looks a bit scraped inside the hinge. Perhaps it shorted against the case?

Quote:

I’m sure you already know, but if my understanding is correct, this of course means your original LCD is probably still usable (or at the very least fixable.)

I'm not putting it back in to find out, but if this one breaks, I'll be getting the original back out of the attic!

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