The Battery is pretty cheap thing to try if you get it at the right place, one such place...
But the slap & unplugging from the mains sounds that it's likely dust build up inside, or Bad Capacitors.
A positive reaction to a "whack upside the head" is a fairly strong indication of a loose connection someplace. eMacs had different hardware issues depending on the variant. The first-gen 700mHz units with Nvidea video hardware had a bad IVAD cable that caused display issues; the first USB 2.0 eMacs with 1.0G and 1.25G processors had bad capacitors that basically rendered the computer unusable..
Please do "About this Mac" from your Apple menu, then click the "More Info..." button in the resulting window.That launches System Profiler for you, defaulting to the "Hardware Overview" screen. Looks something like this:
Note I've NOT shown the serial number. Copy/paste everything above "bus speed" into a response and we can better address what's up with your eMac and how to deal with it.
Thanks for responding.
I went ahead with a big clean of the computer, inside and out, and changed the battery, as BDAqua suggested; and so far, so good. No problems last few hours with monitor crashing and, in fact, I can report my computer's speed has improved by 50 percent. Still, have to give it a few more days, I think, before I can give it the all clear. But, in case it is what you say, below are the details you suggested I post. I've had the emac since 2004 and have had very few problems with it and, certainly, this is the first time I've had a black screen issue. What do you reckon?
Machine Name: eMac
Machine Model: PowerMac6,4
CPU Type: PowerPC G4 (1.1)
Number Of CPUs: 1
CPU Speed: 1.25 GHz
L2 Cache (per CPU): 512 KB
Memory: 768 MB
Bus Speed: 167 MHz
Boot ROM Version: 4.8.2f1
That's all good news. You have the later and better USB 2.0 eMac. However, the model is one containing groups of units affected by the logic board issues with bad capacitors. The logic board issues were most commonly associated with these serial number ranges:
- G8412xxxxxx- G8520xxxxxx
- YM412xxxxxx - YM520xxxxxx
- VM440xxxxxx - VM516xxxxxx
[again, don't post your serial number here]
If yours is in the list, all you can do is keep an eye on it. Keeping it clean like you've done should help keep internal temps down and that may help longevity. The repair--if the shop can find an unaffected logic board---is nearly as much as a new Mac Mini.
If your board goes, and you are within driving distance of Salem OR USA, there is a shop that offers a low-cost repair of bad eMac logic boards rather than a replacement; it's much less expensive IF you don't have to ship a 50-pound computer round trip.
Your particular eMac can take advantage of newer, larger RAM modules that were not available when Apple engaved the specs in stone (Apple says 1GB max RAM). With the proper modules, you can increase RAM to a total of 2GB with two of these:
We have one of the above installed in my wife's USB 2.0 eMac alongside an original 256MB stick for a total of 1.25GB RAM and it's completely stable. However, you should get the RAM from the source I mentioned as they test in Macs. Similar RAM form a retail outlet may be PC-only.
eight years worth of accumulated dust dispelled by few sprays of compressed air.
I did that with a G3 minitower. Had no idea there could be that many generations of dust bunnies inside a computer. The "my bad" part was I did the big blow-out while the computer was on the kitchen table. That got me banned from cleaning computers anywhere upstairs.