Currently Being ModeratedMay 28, 2011 6:02 AM (in response to Richard Tanner)
Resetting the Logic Board
Resetting the logic board can resolve many system problems. Whenever you have a
unit that fails to power up, you should follow this procedure
before replacing any modules.
1 Unplug the computer.
2 Press the Power On button on the front of the unit.
3 Open the side access panel.
4 Remove the battery from the logic board.
5 Wait at least 10 minutes before replacing the battery.
6 Make sure the battery is installed in the correct +/-
7 Reassemble the computer and test the unit.
This procedure resets the computer’s PRAM. Be sure to
check the computer’s time/date and other system parameter settings
Power Mac G4: Computer Does Not Power On, No Fan Movement
Cheers, TomPM G4 1.25HGz MDD, PB 12" G4 1.5GHz, Mac OS X (10.5.8), (10.4.11, 9.2.2) iSight
Currently Being ModeratedMay 28, 2011 6:45 AM (in response to Texas Mac Man)
Just tried that and it makes absolutely no difference.
I've now been assured that it was working last night - so whether it got a bump on the journey to me... I think the PSUs in MDD and QuickSilver machines are more delicate than butterflies in my (pretty abysmal) experience.
I've tried leaving it unplugged for several hours - which I found as a recommendation on one forum. But after that, the fan spun even less than it had done.
I'm now trying leaving it plugged in for a few hours to see if that does anything, but the QuickSilver I had before would turn on for a few moments if left plugged in for several hours... and then died again.
I've tried several power cables and different plug sockets, etc.
Currently Being ModeratedMay 28, 2011 8:04 AM (in response to Richard Tanner)
I'd try unplugging/replugging the power supply's Molex connectors that connect to the logic board. With older electronics, sometimes simply reseating connectors makes a difference. But your power supply might've given up the ghost, too. One source is www.dvwarehouse.com/G4-Power-Supply-c-247_476.html.
Currently Being ModeratedMay 28, 2011 8:56 AM (in response to Richard Tanner)
I had the same symptoms as you're having on my MDD 1.25 a couple of months ago. Went through all the possible culprits that you did...resetting pmu, removing/reinstalling ram, removing battery and disconnecting the powersupply from the main board, booting with the adc monitor detached, leaving it unplugged for days...etc. etc. nothing worked.
I ended up getting a refurbished psu off of ebay and that was the problem for mine. The one I got was ~$85 shipped to Hawaii but I've later seen refurbished ones for as low as $30. I was on the fence about parting it out or fixing it too.
Good luck and hope you get it worked out.
Currently Being ModeratedMay 28, 2011 1:43 PM (in response to Richard Tanner)
Nothing has worked at all. I've tried cleaning the dust out from the bottom corner as the CPU area was full of fluff.
I'm not going to buy a new PSU as I've never found one for under £90 and it might be the logic board anyway?
Has anyone else got any thoughts because at this point I am planning to rip the hard disks out, remove the ram and DVD drive and then take what's left outside and smash it to pieces and then set fire to the pieces.
What is the PSU made of? China, cotton candy and butterfly wings?
Currently Being ModeratedMay 29, 2011 6:29 AM (in response to Richard Tanner)
I've just had another go at repairing the MDD.
I've removed and reseated the Molar cable.
I've removed and reseated the CPU card.
I've removed and replaced all the easily-accessed cables / components.
I've left it unplugged overnight.
I've left it plugged in all morning.
After all that... the PSU still whirrs for less than a second, and then dies.
The fans all come on for a moment and very occasionally a light on the logic board.
Does anyone have any idea if it's likely to be the PSU / Logic board or the CPU card?
Is there any way to diagnose this further as I am not going to fork out for a new PSU if I'm not entirely sure that is the culprit.
Currently Being ModeratedMay 29, 2011 10:37 AM (in response to Richard Tanner)
Can you check the voltages on the PSU?
You can convert an ATX PSU to use in an MDD...
Currently Being ModeratedJun 10, 2011 10:14 AM (in response to motox299)
It would all depend what is wrong, if it is one of those items that is defective, then there are many reports of replacing them curing the problem... but it caqn be so many things with MDDs.
Currently Being ModeratedJun 8, 2012 10:23 AM (in response to Richard Tanner)
i have the mdd 1.25 and one morning i turned it on and went to shower. came out and it was dead and my modem had restarted so i assume the power went off or surged. computer didn't do anything when i hit the button. i bought another one just like it for $100, pulled the hard drive and ram and put it in the newer one and all is well. now i am running two hard drives and have the older one for parts. i am suspecting the power switch is bad though because the newer one is so easy to turn on. i had to push the button just right and hard on the older one. j
Currently Being ModeratedJun 10, 2012 11:16 PM (in response to Richard Tanner)
While I have never owned a MDD, I did encounter the same issues with a QuickSilver a few years ago. Also purchased from eBay. Running in the pictures, and asured to run just the same when it arrived.
In the end, it did turn out to be a faulty power supply. While I would have loved to sink the money into the fix, I had a back Digital Audio Dual/533 that seemed to out pace the Quick in every way, so I ended up selling it on Criag's List for parts. I don't know if this will help. But I would be willing to say it's the PSU, if you can find one for a reasonable price, and if this is your primary mac it might be worth the money.
Currently Being ModeratedJun 21, 2012 3:16 AM (in response to Richard Tanner)
hey seems like a common problem with this G4!!! cross finger my Gigabit ethernet G4 never got that symptom...
didn't see that thread so I did my own...
basically I thank everyone for the info I'm trying everything possible
Currently Being ModeratedJun 21, 2012 8:39 AM (in response to Texas Mac Man)
actually texas man for me your info from the apple knb has gotten me back to the no power and just fast light when pressing the power button
I did what people told (see my post) to remove the cooler plate from the processor and restart without it! this is a great stuff it works any time! but then I'm still stuck with no image and red light on the motherboard with no little fan turning
the strange stuff is when pressing Shift + power when switching off the comp the actual small fan attached to them motherboard is turning so their is something that doesn't its job.
I tried another proc but nothing, another vid card nothing...