Mysterious Broken Mac Mini G4 - Any Help?

[Beeble]

Greetings,

I recently came into possession of an old Mac Mini G4 that was broken and about to be binned. Personally, I can't just accept that things are broken without making an attempt to fix them and, in the past, I've brought quite a few dead macs back to life, so I'm up to the challenge.

Here's the situation:
- No chime
- No video signal
- No power LED
- HDD spins up the second it's plugged in, without touching the power button
- Pressing the power button causes the fan to spin once before giving up
- Power Adapter is OK; tested the voltage with a multimeter
- RAM and clock battery are OK; tested with another machine
- Logic board is held in with only one screw for some reason

Any ideas?

 

[ApplesDotCom101]

I think for the no chime a corrupt install of OS X? I'm totally guessing how to fix it.

 

[flyrod]

Sounds like it's been apart. Is the LED and speaker plugged in? Ram seated correctly? Anything clearly broken/burnt on the logic board? Does a mouse plugged into a USB port light up? If the fan and speaker are not plugged in, it might shut itself down for lack of cooling.

 

[0248294]

I think for the no chime a corrupt install of OS X? I'm totally guessing how to fix it.

The Chime has absolutely nothing to do with the operating system. It's part of the Mac's Power On Self Test, in order to confirm it was able to boot, which will be followed by the Mac seeking for and loading the operating system. This is like saying a corrupted Windows installation will prevent a PC from booting to its BIOS, just inaccurate.

If it doesn't chime, it does not get to the aforementioned POST, thus the Mac was not able to boot properly. That could be anything from a broken logic board, to a dead CPU, to something overheating. Check if the thermal paste is still OK, and/or (straight up) replace it. That stuff tends to age badly. Also, if you can, try a different stick of RAM and a different HDD. The Mac might not like one of those things. If all else fails, the logic board and/or CPU might be broken, and sadly at that point the machine itself is done for. Unless you buy a new LB, but you might as well buy a new Mac Mini G4 at that point, who knows what could be wrong with the other parts.

 

[for this]

Some SMD component, such as a small ceramic capacitor, is missing?

 

[MagicBoy]

Duff logic board most likely. Scrap it...

 

[Beeble]

Thanks for the input.

Sounds like it's been apart. Is the LED and speaker plugged in? Ram seated correctly? Anything clearly broken/burnt on the logic board? Does a mouse plugged into a USB port light up? If the fan and speaker are not plugged in, it might shut itself down for lack of cooling.

No sign of damage on the logic board and I've reseated everything, checked the connections and tried different RAM. Mouse doesn't light up and nothing appears to be receiving any power except for the HDD and cooling fan which just spins once before giving up. Discouraging =/

If it doesn't chime, it does not get to the aforementioned POST, thus the Mac was not able to boot properly. That could be anything from a broken logic board, to a dead CPU, to something overheating. Check if the thermal paste is still OK, and/or (straight up) replace it. That stuff tends to age badly. Also, if you can, try a different stick of RAM and a different HDD. The Mac might not like one of those things. If all else fails, the logic board and/or CPU might be broken, and sadly at that point the machine itself is done for. Unless you buy a new LB, but you might as well buy a new Mac Mini G4 at that point, who knows what could be wrong with the other parts.

Removed the heatsink only to find that there wasn't an ounce of thermal paste left intact. It had completely solidified and the remaining compound seems to have bonded to the underside of the heatsink. This would, no doubt, cause pretty serious cooling issues, but could it really detect a cooling issue and shut itself down that quickly? I've got a bunch of half-tubes of arctic silver kicking around so I guess there's no reason not to replace it for the sake of elimination. I've considered reflowing the solder, too. Think that might do any good?

 

[0248294]

Thanks for the input.

No sign of damage on the logic board and I've reseated everything, checked the connections and tried different RAM. Mouse doesn't light up and nothing appears to be receiving any power except for the HDD and cooling fan which just spins once before giving up. Discouraging =/

Removed the heatsink only to find that there wasn't an ounce of thermal paste left intact. It had completely solidified and the remaining compound seems to have bonded to the underside of the heatsink. This would, no doubt, cause pretty serious cooling issues, but could it really detect a cooling issue and shut itself down that quickly? I've got a bunch of half-tubes of arctic silver kicking around so I guess there's no reason not to replace it for the sake of elimination. I've considered reflowing the solder, too. Think that might do any good?

The CPU heats up pretty quickly, and if it notices that the temperature is ramping up too quickly, it can shut the thing down pretty damn fast. Trying some Artic Silver wouldn't hurt. Just try that, if that doesn't work, reflowing is still an option, since you've got nothing to lose.

 

[dustinschings]

Perhaps the "card" that the HDD and optical plug into is bad? Or the slot on the logic board that the card goes into?

Good luck! If you get it going, they are easy to OC up to 1.5GHz safely. There is an option of 1.67GHz I believe, but that makes it unstable. I can say I have taken a 1.25 to a 1.5GHz no problem. Cannot say if it helped much or not as I never performed any benchmarks back then.

Good luck!