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G4 excessive brightness on any monitor

Submitted by NancyS on May 20, 2007 - 7:37pm. PowerPC Macs

I haven't even figured out if this is a hardware or software problem, but my favorite photos look ugly and my eyes are worn out from reading the text.

symptom: display is consistently far too bright even when its hardware control is at the darkest setting, and it's fuzzy to varying degrees (it changes randomly) at all settings of font smoothing. Probably coincidentally, my months old DVD-RW needs to be cleaned every few burns. Other than that everything is working flawlessly.

things we've done:

1.started up from 10.3 on a separate drive, OS9, the Tiger installation CD, and in safe mode - no change
2.changed the battery & reset cuda; reset the NVRAM - no change
3.removed unnecessary peripherals and 3rd party system preferences - no change
4.tried 2 other monitors (with built-in cables) - no change
5.tried another graphics card and removed tv card - no change (to the brightness/contrast)
6.re-calibrated the profile in the "Displays" preference pane
7.the program "Gamma Control" will increase the contrast and black level to 150%, which makes things better but still too bright
8.ran rember (gui rapper of Memtest version 4.13), with 3 loops -All tests passed

What should we do next? I don't want to take to be repaired if it's a software issue or a user installable part.

Thanks
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System Profile

Mac OS X version 10.4.9

Hardware Overview:
Machine Name: Power Mac G4
Machine Model: PowerMac3,5
CPU Type: PowerPC G4 (2.1)
Number Of CPUs: 1
CPU Speed: 933 MHz
L2 Cache (per CPU): 256 KB
L3 Cache (per CPU): 2 MB
Memory: 1.25 GB
Bus Speed: 133 MHz
Boot ROM Version: 4.3.3f2

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dankephoto's picture

reset pram?

Submitted by dankephoto on May 21, 2007 - 12:09am.

didn't see that specifically mentioned, though I bet you already tried it (holding P-R-opt-cmd on startup.)

It's a hardware/firmware/pram/nvram issue. You've proved SW ain't the cause. The problem has to be on the logic board.

Try this - remove pram battery and unplug the AC supply. Repeatedly press the power-on key (to fully drain any leftover energy in PS), then leave the mess sit in this state for a few hours, overnight even if you want. Re-install the battery and AC, power it up. Works sometimes to cure weird problems like this.

Also, have you got a PCI display card about? Worth seeing what result you get.

dan k

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Is a "PCI display card" the s

Submitted by NancyS on May 21, 2007 - 2:54pm.

Is a "PCI display card" the same as a graphics card? If so it's been done (#5).

I removed the pram battery (#2), but only let it sit for a couple of minutes. The computer forgot the date, does that mean that it was enough?

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hmmm

Submitted by evilrobot on May 21, 2007 - 5:48pm.

test voltage coming from power supply maybe? this is just a shot in the dark, but if the DVD is getting inconsistent power levels, it'll act like it needs to be cleaned, when really it doesnt, and that MAY also be responsible for the video...

I may be entirely wrong though, like I said - this is just a guess.

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dankephoto's picture

re: Is a "PCI display card" the same

Submitted by dankephoto on May 21, 2007 - 6:41pm.

PCI vs. AGP. The stock vidcard is an AGP card, occupying the AGP slot. A PCI card would go in one of the PCI slots.

dan k

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the card we tested was also A

Submitted by NancyS on May 21, 2007 - 7:38pm.

the card we tested was also AGP graphics.

Since this problem is very specific, and has stayed this way for months, I want to know if other people have seen a problem on THE VIDEO ONLY that was caused by the CPU, power supply, or motherboard.

How often does just the AGP slot/connections go bad?

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coius's picture

What connection are you using?

Submitted by coius on May 21, 2007 - 9:03pm.

DVI or VGA? if it's DVI, are you using an Adapter to go from DVI to VGA?

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VGA, no adapter

Submitted by NancyS on May 21, 2007 - 9:15pm.

VGA, no adapter

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