PowerMac G4 MDD's PSU Makes spark noise!!

[gmorapap]

Hello everyone!
I have an PowerMac G4 MDD, i have bought this system about 12 years ago, and i had no problems until the past month... The problem is: when the computer is powered off, the psu makes some kind of spark noise, and i'm very scared about an explosion or something like that...
What do you suggest me to do with this problem?
Thank you!

[FdB]

Unplug it when not in use.

If the machine functions fine when actually booted/running, plug and unplug it accordingly. Hopefully your clock battery is okay and you won’t need to reset every time you plug the machine back in and boot it. A surge protector strip with an on-off switch would easily facilitate this approach.

Sounds like PS is getting ready to quit. (Anyone else here experience this spark / electrical-arc noise prior to failure?) Notice any different smell around this machine? Ahh, ozone.

I’ve yet to delve into the actual circuitry of one of these power supply(s)… but I wonder if like most electronics (like television instant-on features), the PSU reserves / retains a certain amount of electrical current while plugged in, in order to facilitate a faster on-time, upon demand?

Of course, I would open the case door and then under darkness, see if I could witness an arc / spark coming from the power supply… just out of my own curiosity. How stable is your electricity where this machine is plugged in? Voltage surges and other possible line fluctuations could possibly cause this, yet it is likely that the PS is signaling it’s imminent farewell.

And then you, like so many of us here eventually, will begin the quest for a new PS. The on-off power strip routine might garner more life, or it could place more stress on already weakened circuitry… and hasten what might be the inevitable.

AND… blow all the dust and fur-balls out of the machine with compressed air, with the machine unplugged. (Careful around the fans, they were only designed to turn so fast.)

Best of luck. Don’t get in any big hurry, someone else here may have better info.

[GaryN]

Everything that Fury wrote above is valid;assuming there is actually an electrical arc of some kind occurring.
Personally, I'm a little more skeptical.
The first thing to do is identify the noise. "…some kind of spark noise" is too vague to really get anywhere.
Are you certain it's actually coming from the PSU?

Note: The odds of an "explosion or something like that" are slim to none. In 40-odd years of electronics, I've seen many failed PSUs. Most of them had one or more burned-out components, none of them failed at power-off-always at power-on or at random, and not one ever exploded.

So, find the noise. This means, get the thing up off of the floor so you can actually tell where the sound is coming from. Most likely source, the speaker in front is making the popping sound. If not that, open the side and listen. Holler back when you have a better idea of where it's coming from.

[IIO]

batteries do explode, transistors dont.

but i would make sure that i have backups of important data when my old mac starts to change its behaviour.

[DieHard]

It is rare, but I have seen some pretty bad power supply melt-downs (although never an explosion), sparks...yes, a very loud pop...yes, and even a small fire that quickly dies after burning some plastic. Capacitors sometimes die a violent death, but desktop power supplies are much less likely to cause a house fire than, say, an overheated laptop ac pack or a defective laptop battery, both of which have many cases of igniting other items and burning a building to the ground.

As suggested, it would be wise to...
1) Turn it off by a power strip, when not in use
2) Examine it closely by removal, then try to determine if you have a stiff fan (may cause noise) and look for char marks, burn spots, swollen capacitors, or course, remember not to touch anything that will may cause a shock even while unpluged.

[gmorapap]

Thank you so much for all advices! 
Yes inside appears something like blue spark light...
Now i'm looking about an refurbished mdd power supply, in order to change that noisy and now problematic one!
Anyway it's a miracle how that thing works after those years of heavy and daily work...

[FdB]

Yes, as stated by GaryN... direct email contact with Andy Cuffe ([email protected]), in Austin Texas is perhaps the best route to a PSU repair/refurb, to date.

Found another possible, unconfirmed stock source last night (holiday business closures), but may call this coming Monday. ReUseTek in Tustin, California / 855-305-7897 listed the ACBEL API1PC36 POWER SUPPLY for $40.00. SKU 50000646

Again, condition - reputation - quality and actual availability have yet to be confirmed.

Interested to know if the spark that gmorapap reported can be best viewed... through the 'fan end' of the PSU or from the back side, where the power cord enters.

[Jakl]

Not sure where you're located, but here's a good alternative in Texas. $75 gets a complete rebuild.

https://www.ebay.com/itm/REPAIR-SERVICE-Apple-PowerMac-G4-Mirror-Drive-Doors-Power-Supply-MDD/141030901102?hash=item20d618c56e:g:~RsAAMXQysxSAA61

GaryN's link for refurbished MDD power supplies is so important for those needing a PS for a MDD.
I would really like to see a sticky placed in General Hardware Discussions under a heading like - Powermac G4 MDD refurbished Power Supply - with the link from the post or even the business name and number of the business etc.

[DieHard]

Great Suggestion....

I made a new childboard Here...
http://macos9lives.com/smforum/index.php/board,178.0.html

Please post all part Vendors/Sources Here

[Jakl]

Thanks DieHard 

[mrhappy]

Yes this is bound to be useful to many!