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Level 1

60 points

eMac random black screen - advice needed

I have an eMac G4 1GB, max RAM, OS10.5 Leopard. I have recently had the black screen problem. It randomly turns black, with everything running in the background. The screen then returns to normal a few minutes later. It sometimes runs for hours without a problem, other times it will happen several times a day. The machine runs perfectly otherwise... would be great to fix it if possible.

So far I have tried the following:

- Opened the eMac and cleaned the interior of dust

- PRAM reset

- Replaced the battery (which was dying because the date would reset on unplugging).

Are there any other straightforward things I can try, or is this most probably a hardware failure and ultimately a write-off?

Any ideas appreciated.

eMac 1GHz, iBook 14, Mac OS X (10.5.8)

Posted on Mar 19, 2013 6:05 AM

Best reply

Allan Jones

Level 9

68,726 points

Posted on Mar 19, 2013 8:28 AM

Screen problems like that are often hardware problems. Can you correlate the failure with temperature--like the time from cold start to the problem appearing? If consistent, there could be a thermal effect happening. Heat causes some component to fail.

Please run System Profiler (in Applications > Utilities) and see what its first screen reports for "Model Identifier." It is the second line in the image below

The reason for doing tis is that there are two version of the 1.0GHz eMac. Most will have the Model Identifier "PowerMac4,4" but there were a few 1.0G models shipped for edu-only use that had the identifier "PowerMac6.4" (indicates a USB 2.0 logic board) The latter were not shipped to commercial accounts but have appeared in private hands as schools shuck them off when they upgrade hardware.

The 6,4 variant with 1.0 and 1.25Ghz processors had a near-fatal logic board problem usually (but not always) found in these serial number ranges:

G8412xxxxxx- G8520xxxxxx
YM412xxxxxx - YM520xxxxxx
VM440xxxxxx - VM516xxxxxx

If you have the 6,4 identifier, see if your computer falls in these ranges.

The very first eMac 700s had a bad IVAD cable that caused video problems but that was fixed long before the 1.0ghz units were developed.

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18 replies

James_A Author

Level 1

60 points

Mar 22, 2013 10:22 AM in response to Allan Jones

1) Lol... no tobacco of any sort roundabout here these days!

2) No dirty power issues. Perhaps one black out. Reminds me though that the plug has been knocked half out accidentally a few times while the emac was on, which killed the power.

Allan Jones

Level 9

68,726 points

Mar 22, 2013 11:26 AM in response to James_A

Ok, I'll pass on to my young expert. Not sure why he asked about smoking but he's been inside a lot more macs than I.

Sudden power cuts have historically been tougher on hard drives than other components, alsyhough I suppose that could have a effect on the power supply. However, power supply probloms don't tend to be intermittent.

Can we clarify one thing: when the screen goes black, does it come back on a some point without requiring a restart?

James_A Author

Level 1

60 points

Mar 22, 2013 11:44 AM in response to Allan Jones

Yes, it just pops back into life and everything is how I left it. It's just the screen shutting down with everything still on in the background. Sometimes the blackout lasts only a minute or two, other times 20 mins or so. Some days it runs for hours without a blackout... which is why I haven't given up on it.

eMac random black screen - advice needed