G4 suddenly shuts down

Hi

from the info you give it certainly sounds like a hardware problem. Both overheating power supply or CPU could cause this. Check that ALL the fans are working. Also you could check the seating of all ram and pci cards by removing and replacing. likewise with HD power and ATA conections, They can become dirty or corroded after time. Also look for burnt areas on the motherboard. After this you should reset the motherboard by pressing the small cuda button Near the Graphic card slot. on the motherboard for a few seconds before powering up.
If you don't feel confident about this you should take it in the the store... Good Luck!

In addition to Gordon's excellant advice, I would bootup on your Apple Hardware Test disk and run it and see if it flags anything.

Cheers!
DALE

Go to this link regarding the front panel boards on the G4 towers

http://www.smalldog.com/newsarchive/techtails_display.php?id=44

Hope this helps

Hi,

I was facing a similar problem with my G4 (spontaneously shuts down). With general use (i.e. iTunes, Safari, basic word processing), I can get about 4-5 hours of usage before shutdown, but only about 1.5 hours during heavy video render sessions.

Although I suspect something is wrong with the logic board, I think something else may have contributed to the problem (please correct me if I'm wrong, as I really don't know squat about hardware). Could it be that I have too many things plugged into my mac?

- Yamaha MIDI keyboard for use with GarageBand (MIDI-USB interface directly into tower)
- External Lacie Firewire hard drive
- Speakers and sub connected to sound card
- USB hub connecting laser printer, scanner, Mac keyboard (which has a Palm Pilot connected to it via USB)

Any info would be greatly appreciated!

Desperately,

Steve Cicione

Dual 1 GHz, G4 Mac OS X (10.3.9)

Steve,

Did you ever get your problem figured out? I'm having the same symptoms (and a search of this board indicates that sudden inexplicable shuts downs are affecting many people).

Thanks,

Paul

It sounds like a cpu thermal issue. It could be a slow fan or one blocked with dust, etc. More likely, it sounds like marginal cooling from the heatsink.

I would look at the heat sink to cpu mounting, particularly if the heat sink was ever removed without the thermal interface being replaced before re-installing.

I have used various thermal greases in the past, but they all will tend to dry-out with time and lose effectiveness, particularly the aftermarket "silver" brands ... they work great when first applied, but fade over time.

A more stable, long-term solution would be a quality, cpu-grade phase-change thermal film. I've had good luck ShinEtsu PCS-TC-11 ... easy to apply, usually can be had in 1" squares which fit nicely onto G4 heatsinks. The key to applying those is everything must be clean ... isopropyl alcohol works wells.

This may not fix your problem, but is good preventative maintainence.

Good luck!

Hi Kooler King,

Thanks for the very useful reply -- I was thinking it could be an overheating or fan issue (it's a shame that that machine does not have those sensors). I will check it out. Interesting, it can shut down anytime, but can also stay on when used, but in sleep mode it invariably shuts down. This might indicate something (e.g. main fans off during sleep, therefore CPU heat sink may be at fault).

Thanks,

Paul

Some time ago a HUGE thread here expired - it was called "SPOS - Sudden Power Off Syndrome". I was hit by it big time.

After you have a SPOS event, look in your Console.app logs. If you have something along the lines of "ApplePMU::PMU FORCED SHUTDOWN, CAUSE = -122", you are a victim of SPOS. For me it would happen typically in the summer (I don't ever remember a winter event), warm ambient temps (above 78°F) and/or with above average CPU usage. Heat & activity lead to these SPOS events. Temporary relief (which I can attest to), came from running with the case open about an inch for better flow.

There were lots of ideas on how to solve the problem. Some suggested drilling a blowhole in the top (I found that one beyond amusing), some tried all kinds of mystical resets, others focused on incantations. From what I remember, the only sure-fire way was to get a new power supply (and hope that one wasn't affected as well). I replaced my power supply in June 2005, and haven't had a problem since. I consider that proof that it was the powersupply.

I remember when I was in the market, I though these people must think I'm on crack to pay $99 on ebay or $160 at whatever.com to get a power supply. If you have an ADC monitor, you have no choice, you are forced to get the same power supply. And that new/refurb/replacement may also be affected for all you know. It's not like they come with a "I'm a dud" sticker.

I found some guides on the internet on how to change a PC ATX power supply into something that could work in a Quicksilver. Quicksilvers (and anything else that can has an ADC port) have a voltage present on them that you won't find in ATX power supplies - +25v. And that voltage has to be present all the time - it is required to start up.

I settled on a CoolerMaster high efficiency power supply. There were some... tradeoffs that had to be made. First, no ADC ever (not a problem). Second, that choosing any non-Apple supply, there were going to be positional challenges. The fans & exhaust were just not suitable. My PSU has the intake fan facing the inside wall (there is about 1/2 inch of space between it and the wall). And it just sits there on the shelf - the DVD drive bracket had to be removed, but the flipside was the new PSU had nice, long & plentiful molex connectors. I how have 5 hard drives (some just aren't bolted down to anything) inside my quicksilver, the DVD recorder and a Radeon 9800. Not to mention the power rocker is inaccessible (though it doesn't matter because the computer turns on & off as before - but if there is a huge knob or something on the back, think again - you won't have room).

The PSU power inlet has to be in roughly the same place too, or you'll be facing more case alterations. I trimmed off maybe 1/2 centimeter total. And while the exhaust is blocked a bit by the case's fan grille, the efficiency of my PSU overcomes the restricted flow. It has only kicked up a single notch once - and it was over 86° ambient temp. I remember thinking "what is that sound...." because I had never heard it before. The back of my PSU is almost a total grille - a circular shaped fan/exhaust may not be situated well.

The power supply connector also needs to be taken into account. It is best to have a 24pin power supply motherboard connector - it will have to be trimmed down to 22 pins. Then some pins will have to be rewired. On the quicksilver, the P4 4pin +12v CPU connector also needed rewiring (at least on my PSU). Removing those pins from the connector can be done by using those supermarket eyeglass repair kits. Jam it in on either side and pry back and forth to release the 2 small metal tabs from the plastic latches inside the connector. Takes some getting used to.

The last problem is the missing +25v. It takes the most work. There are suggestions of using a wall wart (of probably +24vdc) to supply it. It doesn't need to be high powered, but as I have yet to do that, I don't know what it should be. I still have the original power supply sitting below the computer. Its plugged in and still operational, but the fan never turns on. I have the +25v (and ground) snaking in through the rear holes and into the motherboard 22pin connector.

I'm not about to say it was a piece of cake, because removing the pins from the connector was highly annoying. And if your original PSU is dead, then it won't be able to feed +25v for start up. When my laziness passes (hasn't happened so far this decade), I'll just remove the original powersupply from the feed and substitute a wall wart.

In the end, I didn't save a whole lot - my PSU was a pricey $80.00 ($76 today), but I thought that it (the CoolerMaster RS-450-ACLY) was worth it. And I still think that today. The reviews on it are superlative. Comes with blue light too. The gimmicky 3 1/2 watt meter addition I had sitting in my evacuated zip drive bay - it now has another hard drive, but it slid in there just fine. I was using about 110 watts according to its (somewhat imprecise) readout.

Oh, and another thing was the case fan connector. I had to cut that off the original supply and attach that to the floppy cable. Not a huge problem - but that line to the fan is short!!!

And I haven't had a SPOS event since.

Hi Anaxamander,
Thanks for your detailed comments. Co-incidentally, I just did a similar thing. My PSU went 'bad'; my G4 would shut down, then not restart most of the time -- a voltmeter check on the 'Power Good' line read 1V, rather than 5V.

I found a highly rated efficient PSU (do a Google search to read the reviews), manufactured by Seasonic (S12-330 330 Watt for $47, S12-380 380 Watt for $60 from Case-mod.com when searching using Froogle.com). As with you, fitting the case into the G4 is not perfect, but it is pretty well attached using the shelf bracked and one of the case Torx screws --- I did not have to cut the case. Also having the AGP G4, I do not have the requirement for the 25V line.
My machine boots up fine every time now, with no shut downs.

[I have not affiliations with Seasonic or Case-logic other than owning the PSU]

Hello

I just posted a Thread about this too!

Can anyone tell me what the origional specs are for a G4-450dp power supply, i just had a new one installed and since them i have experienced my computer shutting on its own.

I see that they installed a;
Ac/Bel API-9841-291 LEVEL 3
Date B0022
Rev B
AC Input:
100-140v, 47-63hz 10.0 A
200-240v, 47-63hz 5.0 A

DC Output:
+ 5.0v and 3.3v ==== 20.0A and 24.0A TOTAL 126w Max
+ 12.0v-12.0v ==== 8.0A and 025.Av
+ 28.ovs ==== 4.04A

Can anyone verify id if the power supply above is the correct one for a G4-450DP?

I am gonna be running :
- Radeon mac edition with a Dr.Botts ADC adapter to a 15" screen.
- ATA133 PCI card with 4x 300GB Hard drives
- D-link Firewire PCI

G4 450x2, PB12 1Gig, Mac Mini 1.42Gig Mac OS X (10.4.3) Ipod video, Nano, iShuffle

Logic Pro:

Here's the power supply info for a Gigabit-Ethernet Mac:

Power Supply, 338 W, 22-pin, PMG4 ( Gigabit Ethernet) 400-500Mhz
Apple Assembly numbers: (614-0112), (614-0120)
AcBel part #s: (API9841-281), (API9841-291)
The Apple part number is 661-2332.

Trickle voltage across pins 11 (ground) and 22 ➕ should be 28 volts with the Mac powered off but plugged in. ( Pinout Diagram)

Gary

Thanks again there

I see that it says AcBel part #s: (API9841-281), (API9841-291)

Is (API9841-281) and (API9841-291) one and the same?
Asking since mine reads only (API9841-291)...

I i might sound silly about this, but just to be sure since it looks a bit diferent, can you just verify this?

thanks again

Logic Pro:

The two API numbers and Apple Assembly numbers are most likely two versions of the same basic PSU. I just re-read the specs you posted and the +28 volt output leads me to believe it's the correct unit. The QS Mac and the pre-Gigabit Ethernet Macs have a different number of pins at the connector. The MDD PSU is way different. I'm convinced that it's the correct one. Whether or not it works properly is another story...

Gary

Thanks again

I was just worried since my G4 is a dual and not a single Processor, but yes referring to what i posted which are details from inside the machine now, as you say is correct.

What you recommend i do next? go back to the Apple Authorized shop and show the guy a print out of this thread and ask him to consider investigating more with a ADC screen?

He never tested it with a ADC monitor for sure.

Is this Tower on a UPS? Make sure it is good and that it's battery (the UPS) is not dying. I've seen plenty of posts in forums where a faulty UPS also caused this (also worth trying the simple solution of another outlet/power strip if that it is all hooked up to).