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 Post subject: Pismo Backlight
PostPosted: Tue Sep 02, 2003 7:14 pm 
Hello all,

I'm trying my hand at fixing up a pismo I bought at an auction. I was wondering if any hands-on fixers might be able to offer some advice. The pismo does boot up, but the backlight is off ( I can just barely see what's on the screen with a very bright light shining on it). I replaced the inverter board hoping that would fix it, but no luck. I had some questions that I was wondering while troubleshooting.

a) I noticed that on both inverter boards that the LED on it (which is the green "power" light on the powerbook) never comes on when the system is powered on. Does anyone happen to know if the LCD comes on independent of power to the backlight? ( for instance, if the black-and-white backlight cables are completely unhooked for testing purposes.) I'm wondering if my backlight is actually bad, or maybe my logic board, or maybe I've gotten really unlucky w/ my inverters and display cables!

b) I tried to get an external video signal w/ no luck. The signal light on the monitor comes on briefly when I power on the powerbook, and then goes back to "power-saving" mode after a second. Should I be able to view external video without being in the OS (i.e. from powerup) ?

Thanks in advance for any help!
David


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 Post subject:
PostPosted: Wed Sep 03, 2003 10:47 am 
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Joined: Mon Feb 24, 2003 1:58 am
Posts: 940
David,

I believe you first have to boot up the OS before you can go to external mode on the Pismo. You can replace just the backlight, but it isn't reccomended. I'd personally go the new display route.

-Bradley
Powerbookmedic.com


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 Post subject:
PostPosted: Wed Sep 03, 2003 10:55 am 
Bradley,

Thanks for the reply. Do you happen to have any idea on the first question? I'm wondering if the fact that the LED doesn't light on both inverter boards means either they're both bad, or I'm not getting power to the inverter board from the motherboard.

Maybe my logical concept on this is wrong( especially possible because I'm just getting into this), but I figured that the LED light on the inverter board would at least be a good sign that it is getting some power. I'd hate to buy a new display and find that the problem is that the inverter board isn't getting power and I needed to replace the logic board instead.

David


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 Post subject:
PostPosted: Thu Sep 04, 2003 12:45 pm 
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Joined: Mon Feb 24, 2003 1:58 am
Posts: 940
It's difficult to day. Uusally the inverter board doesn't go bad, so it's unlikely two would be bad unless you purchased them from a less than reputable source. One way to force the sleep light to come on is to hold down the shift,fn,ctrl, power keys....(the pram reset) The will cause the light to blink. If the light doesn't blink, then yes it could be the inverter.

-Bradley
Powerbookmedic.com


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