: G4 mdd won't start

Jan 1st, 2014, 09:58 PM
Hello, i have a powermacintosh G4 1.25 ghz single processor fw 400. One day, i decided to take it apart so i can dust it. After putting back together, i try starting it up, but the power light fades and the fan starts screaming!https://www.ehmac.ca/images/smilies/yikes.gif I know the psu is still good because of a red light on the main board lights up, and i tried hitting the little button on the board's corner(pmu reset, i think) , but that just stops the cd-rom from whirring up. I also tried disconnecting all the drives, but still, the same problem. Do you think i need new thermal paste for the processor? Well, help would be appreciated, as i really miss using it, nomatter how much times it angered me. https://www.ehmac.ca/images/smilies/cry.gif

Jan 2nd, 2014, 07:09 AM
I think what you did is called a CUDA reset with the MDD. Try Googling that. Furthermore, I'd try reseating the RAM and all the cards, check the power connector as well. Good luck!

Jan 2nd, 2014, 10:00 AM
Oh, and i forgot to mention my mac doesn't have the clock battery anymore

Jan 2nd, 2014, 11:47 AM
That shouldn't be a problem. It is supposed to run without the battery. Pretty much equivalent to resetting P-RAM with every cold start, not ideal but pretty harmless.
Just try to check all mechanical connections as I've suggested above. And check if the heat sink screws are well tightened still. I suspect you may have disturbed something mechanical while cleaning.

Jan 13th, 2014, 05:58 PM
nothing works:( i tried booting with one ram stick, same problem. Heat sink won't go tighter either and it doesn't shake. Do you think the mother board messed up when i reinserted it. Or maybe some thing won;t work because i took out the modem or the airport antenna(which i don't use though.) well, sorry for the rushed response and i hope the post isn' seen inactive.

Jan 13th, 2014, 06:27 PM
Remove and reinstall the video card.

The computer won't boot if the any of the cards aren't seated properly, that includes memory, video card, and any PCI cards that may be installed.

Jan 13th, 2014, 06:38 PM
I might suggest resetting the PRAM - on startup hold down CMD-OPTION-P-R and hopefully it "bongs" - hold down for three

Jan 13th, 2014, 07:43 PM
+1 Rob and ChilBear.
@sadmac: try all possible positions of all available ramsticks in all available slots. Keep methodical notes of your progress. The MDD probably has 4 slots (if memory serves me right), so 4 to the power of 4= 16 combinations.
Oh, try to put in a new P-ram battery as well, I think it is a CR 2032, 3V one, cheap enough.
Troubleshooting over the internet is not too easy, believe you me!
Anyhow, here is the MDD Apple Service Source. Enjoy. Download quickly, for those tend to disappear soon: http://tim.id.au/laptops/apple/powermac/pmg4_mir_fw800.pdf
The one for the FW400 model is not to be found in a jiffy right now, for example.
Good luck!

Jan 13th, 2014, 09:55 PM
Oh, and i forgot to mention my mac doesn't have the clock battery anymore

Shouldn't be but very possibly could be the problem. These are not very expensive so spend the $10 before going through any more gymnastics.

Jan 14th, 2014, 02:09 PM
If you can't find any PRAM batteries let me know. I should have some laying around. I think they're little half height AA batteries. Same as on my MDD 1.42

Jan 14th, 2014, 02:45 PM
Yup, 1/2 AA 3.6V.

Just don't let some places charge you their stupid $30 - $40.00 price.

They should be around $10.00 at your local store or if they don't try:
NewerTech 3.6VPRAM 3.6v Lithium 1/2 AA PRAM... in stock at OWC (http://eshop.macsales.com/item/NewerTech/BAA36VPRAM/)

Jan 15th, 2014, 04:02 PM
well i tried messing around with it, and i got some leads. One thing is that the symptoms don't change without the video card and ram. Without the processing card, it obviously just sat there as if it wasn't on.Oh, and another thing is that the processor heats up quickly without the heat sink, and its missing some plastic pieces on the outside

Jan 15th, 2014, 05:21 PM
i tried booting without the ram or video card, but same problem. Some plastic parts on it are also missing, and without the heat sink, the processor heats up quickly

Jan 15th, 2014, 09:15 PM
Well, the machine should start without the battery, as I've been doing that for a long time. Another thing is that i still got the same problem when i tried booting without the ram ( still has CPU and video card), without anything but the CPU, and just with the CPU and ram.oh, and something I've noticed is that the CPU heats up quickly without a heat sink, which i don't know if that's normal(there are also little brownish marks in the circles around the holes in the CPU, which i believe was always there) and that some plastics i left out during re-assembly, which it dumb on my part. Well, im gonna try out the fancy resets and hope works when i can, but for the ones that require a key combo, how can i be sure I did it right, because i don't have a speaker on the machine(loud sounds startle me easily)? Well, i'll still try it and guess i should see the light come on(hopefully)

Jan 19th, 2014, 07:35 PM
Well, i tried to do some investigation, and found that i get the same noise without ram or the video card. the only time it will change is when i remove the cpu, which is obvious.I also found the some plastic pieces were missing from the outside of the computer. Should i try reinserting the motherboard?

Jan 23rd, 2014, 07:05 PM
i tried messing around with pmg4 and found it still wouldn't boot if there was no ram, or if there was no video card