Weird Display on iMac G5 1.8

Hi All you pros out there!

Trying to keep this iMac going a little longer. I have replace a faulty HDD and increased the ram to 2G.

This worked great for the kids for about a month, now I they get funny screen, but if I was to switch the resolutions, it seem to get rid of the weird display for awhile(couple of mins). I thought it was the OS, but since reloading it, it didn't make a difference.

Any comments is appreciated! see pic.

cheesedog said:

This worked great for the kids for about a month...

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Does this mean that you recently purchased this iMac G5 used?

- Nick

That really looks like a video chipset issue to me. I could be wrong though, but that would be my guess.

pigoo3 said:

Does this mean that you recently purchased this iMac G5 used?

- Nick

Click to expand...

Thanks for the reply Nick, no my bro-in-law was too lazy to change out he HDD, so I figured what why not... drop $100 for HDD and ram.. now this problem.

dtravis7 said:

That really looks like a video chipset issue to me. I could be wrong though, but that would be my guess.

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So if it's the video chip, I guess I am hooped?

cheesedog said:

Thanks for the reply Nick, no my bro-in-law was too lazy to change out he HDD, so I figured what why not... drop $100 for HDD and ram.. now this problem.

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I was asking incase you purchased this from someone else (e-Bay or Craig's List)...and maybe it was a preexisting condition. Assuming that it was working fine for your brother-in-law (or maybe this is why he stopped using it). Seems strange for there to be a hard drive issue...and then 1 months use later a video issue creeps up.

Like "dtravis7" mentioned...it could be a logic board/video hardware issue...which there really isn't a whole lot you can do about it. The only other thing I could suggest is...maybe the iMac needs a good cleaning (especially the fan & ducting). Maybe it's overheating causing the issue.

Good luck,

- Nick

pigoo3 said:

Like "dtravis7" mentioned...it could be a logic board/video hardware issue...which there really isn't a whole lot you can do about it. The only other thing I could suggest is...maybe the iMac needs a good cleaning (especially the fan & ducting). Maybe it's overheating causing the issue.

Good luck,

- Nick

Click to expand...

That is a good point. How long does it take for the video issues to show? Right away as soon as you get into OSX? Do you see anything on the loading screens at all?

The 1.8 GHZ model should be an ALS model. Is this a 20" iMac? One thing to check is the display cable to the LCD where it plugs into the Logicboard. I have seen that connector get dirty and cause video issues like that. My iMac G5 did it in fact.

dtravis7 said:

That is a good point. How long does it take for the video issues to show? Right away as soon as you get into OSX? Do you see anything on the loading screens at all?

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Another great point!

@cheesedog: If the iMac video problem takes a little while to occur...this could be related to cooling (good video at first, then video goes bad as the iMac heats up). So could be a cooling issue (dirt/fuzz or a bad fan).

If the video is bad immediately (immediately after starting up the computer from a "cold" or turned off state)...then this would more likely indicate bad video hardware.

- Nick

Thanks for the replies guys!!

iMac is a 20" and it was working fine prior. That's what i thought, heat problem. It's kind of random, what I did notice was this causes the mac to freeze, especially when trying to surf. It almost seems like it's out of memory and takes awhile to respond.

The display is fine through the loading screen until it get to the OSX. This will also be a hit and miss as well, sometimes it loads with the display funny, but if I reboot it may load fine. This is why I am not totally convinced it's hardware.

The display cable to the LCD where it plugs into the Logicboard, is that like the 5 pin connector at the top rear of the unit? I did clean the air ducts when I replaced the HDD, but will check that one connector.

Once again, thanks for the feedback, time to work on the dishwasher, do you guys know anything about dishwashers? LOL!!!

cheesedog said:

Once again, thanks for the feedback, time to work on the dishwasher, do you guys know anything about dishwashers? LOL!!!

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Different internet forum!

I've worked on dishwashers, washing machines, clothes dryers, lawn mowers, refrigerators, etc., etc. Just got to find the right internet forum...or parts supply place (internet page)...that has a good troubleshooting guide...which narrows things down to 1 or 2 possible bad parts for you to order & replace.

- Nick

I can fix dishwashers. What City you in? Grin. I really can.

Report back on that cable. It really did make mine and another users here at Mac Forums do that on the screen.

Ok, I have reseated the connectors and the display cable. Well so far, after about 5 hours of use, everything seems to be a okay!! Thanks to both you guys for your timely response.

oh dtravis7, I live in Canada. Right now it's about 32 F, probably a bit cold for you! LOL!!!

Long walk also for me in that cold.

We get 32º F and lower here in the winter so I am sort of used to it.

I hope that the iMac keeps working. Mine did for sure. Keep us posted.

Congratulations!!! Keeping my fingers crossed.

- Nick