Could failed battery cause black screen when connected to the mains?

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Could failed battery cause black screen when connected to the mains?

I have a 2003 1GHz 15-inch Aluminium FW800 PowerBook G4 Model 1046 connected to a CRT external display. I use the PB powered from the mains as the battery (original) will not hold a charge on its own. The LCD screen will not light although the image can be seen with a strong backlight in spite of having replaced the inverter and the LCD panel. I'm guessing that the other causes of this fault could be a damaged cable or a problem with the logic board. However I understand that as well as the CPU operating at only 50% of its potential when operating solely on the mains, the battery supplies top-up for some high-power functions requiring more than the available mains supply. Could the lack of battery-supplied power additional to the mains prevent the LCD display from working?

powerbook G4, Mac OS X (10.4.11)

Posted on May 14, 2015 5:50 AM

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Answer 1

a brody

Level 10

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May 16, 2015 11:17 AM in response to riverrun

There are in fact two batteries. One is the one that you swap out for power. The other operates the clock and low end functions, including some display functions. When that latter battery known as a PRAM or Clock battery fails after 4 years, sometimes it won't allow the display to run. Getting those batteries can be expensive for the older Powerbooks.

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Answer 2

riverrun Author

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May 17, 2015 4:29 AM in response to a brody

There are no date and time problems which I thought were the signs of a failing PRAM battery.

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Answer 3

ChitlinsCC

Level 7

20,924 points

May 17, 2015 10:32 AM in response to riverrun

Finder > Help > Mac Help > search " pram " = article on display errors...

1st try resetting the PRAM.

Shut down the computer. Turn on the computer and press and hold the Command-Option-P-R keys. Hold the keys down until the computer restarts and you hear the startup sound for the second time.

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Answer 4

riverrun Author

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May 17, 2015 10:45 AM in response to ChitlinsCC

Reset the PRAM: done that. Having changed the inverter and the LCD panel, I think the problem could only be a faulty inverter cable, faulty LCD cable or damaged logic board (from shorting cable perhaps). The question about the battery was a slim hope that it could be something simpler and less obvious than this.

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