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eMac random black screen - advice needed

989 Views 18 Replies Latest reply: Mar 22, 2013 11:44 AM by James_A RSS
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James_A Level 1 Level 1 (60 points)
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Mar 19, 2013 6:05 AM

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)
  • Allan Jones Level 7 Level 7 (29,555 points)
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    Mar 19, 2013 8:28 AM (in response to James_A)

    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.

    eMac 1.42Ghz, Mac OS X (10.4.11), 1.25G RAM + eMac 700mHz 768MB RAM
  • Allan Jones Level 7 Level 7 (29,555 points)
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    Mar 19, 2013 11:25 AM (in response to James_A)

    James wrote:


    Also, I have the rear of the machine (where the air vents are) pressed up against the wall. Perhaps I'll start by moving it away from the wall a little to see if that helps.


    By all means try to get it about 6 inches (~15cm) from the wall. Even though the shape of the case means you can't completely occlude the exhaust flow this way, it could reduce the effectiveness of the exhaust function especially when combined with the Fanmate.


    We have a geriatric PowerMac 6100 that exhausts out the bottom, It struggles even on a perfectly smooth surface. I have to set the case up on 5/8" spacer blocks for it to even run. So exhaust efficiency can be an issue.


    As for its working for a while and then failing, it could be that long-term exposure to the extra heat caused by the reduced fans speed and the proximity to teh wall has damaged some component. Cable insulation can get soft and flow, exposing wires, and logic board component can become cantankerous.  Right now, I'm betting on a cooked video cable, but haven't been inside eMacs enough to say which one.


    I understand fully about the noise issue. At one point, I had a G4 MDD tower and my wife had her 1.42Ghz eMac on the same workstation. I felt like I worked in a shop where aircraft engines were tested all day! Now we both have late-model iMacs and the noisiest things in our work area are two external backup drives and empty stomachs demanding attention!


    Lets see what improved cooling accomplishes and go from there.

    iMac 27-in; Mid 2010 2.93G i7 Quad, Mac OS X (10.6.8), 12GB RAM; ATI5750 1G VRAM
  • BDAqua Level 10 Level 10 (114,670 points)
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    Mar 19, 2013 5:51 PM (in response to James_A)

    For PPC Macs...


    If you have any temps in the 70°C/160°F range, that's likely it.

  • Allan Jones Level 7 Level 7 (29,555 points)
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    Mar 20, 2013 7:47 AM (in response to James_A)

    Can't say what's normal at our end because our 6,4 eMac has no sensors Temp Monitor or iStat Pro can read! Frustrating! My well-ventilated G4 MDD runs about 95F for all but the most taxing tasks. Intel Macs run hotter and the iMac i7 at which I'm typing has smallish fans yet is running at 99F at the moment with 14 tabs open in Safari, and two other programs running in the background,


    I would still try to pull the Fanmate and see how much the temps drop and to see if that stops the blackouts. Remember, a reduced fan speed may suffice when the air paths are clean but can prove insuffient when things get dirty.


    We should consider potential software causes of overheating:


    1) Anti-virus/internet security software: The "pay-for" kind are really bad at running up temps. If you have it, dump it.


    2) Third-party backup software: Those programs that come bundled with external hard drives can be very taxing. I had an external on my OS 10.4 G4 (no Time Machine), and the BU software alone ran temps up 7F. If you have a third-part backup program running all the time, useTime Machine--It does not cause the heating I saw with others.


    3) Safari's Top Sites function can overwork the gear because it relies on a background process "Safari Webpage Preview Fetcher" that is a processor hog. It's hard to remove but easy to neuter so the fetcher isn't activated.


    4) Runaway background processes: Sometimes a process will refuse to gut off. Higher temps can result. If you find that my #s 1 - 3 don't apply, post back and I'l walk you through the search for runaway background processes

    iMac 27-in; Mid 2010 2.93G i7 Quad, Mac OS X (10.6.8), 12GB RAM; ATI5750 1G VRAM
  • BDAqua Level 10 Level 10 (114,670 points)
    Currently Being Moderated
    Mar 20, 2013 11:30 AM (in response to James_A)

    See if the Disk is issuing any S.M.A.R.T errors in Disk Utility...




    Open Activity Monitor in Applications>Utilities, select All Processes & sort on CPU%, any indications there?


    How much RAM & free Disk space do you have also, click on the Memory & Disk Usage Tabs.


    Open Console in Utilities & see if there are any clues or repeating messages when this happens.


    In the Memory tab of Activity Monitor, are there a lot of Pageouts?

  • Allan Jones Level 7 Level 7 (29,555 points)
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    Mar 20, 2013 1:21 PM (in response to James_A)

    For the Fetcher to show in Activity Monitor, you need to change AM's "Show" setting from its default of "My Processes" to "All Processes." The setting is in the top bar of the AM window:


    ActMon settings example.png


    Thus set, some other bandits might show up, too.


    To neuter Top Sites so the Fetcher is not activated, go to Safari > Preferences and:


    1) on the General tab, make sure no "open with" option is set to "Top Sites."

    2) uncheck anything mentioning Top Sites in the Bookmarks tab.

    3) go to "Reset Safari..." in the Safari menu and select the two boxes shown here:


    Screen shot 2013-03-20 at 1.14.06 PM.png


    then reset.


    That procedure gets rid of a nuisance background process without deleting anything. You can restore Top Sites with a few mousclicks should you need it. On a PPC with limited RAM, I find Top Sites is not my friend.


    Even when I upgraded to a hot quad-core i7 iMac, I still turned it off. It;s eye candy I don;t need.


    Camino is more respectful of system resources than Safari in my experience.

  • Allan Jones Level 7 Level 7 (29,555 points)
    Currently Being Moderated
    Mar 21, 2013 9:18 AM (in response to James_A)

    Usually you have to use the computer normally for a while (several hours of typical apps and tasks) then quit any apps you launched before AM will show any bogies. Sounds like you computer doesn't run that long.


    That said, a shutdown at 89F is not likely a thermal issue. Good info to add to the pot of data points, however.


    I have to work my volunteer job this morning but will have a Mac tech with me. I'll see if any of this rings a bell with him. He worked on a lot of edu-Macs at a nearby university.


    More this afternoon, I hope!

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