PowerMac MDD power on issue

[Gaeokerena]

Hi All,

I picked up a PowerMac G4 MDD 1Ghz and 23inch Cinema HD both fully boxed in fantastic condition. A real prize!

However...

I cannot get this thing to boot up.

When pressing either the mac power button or the display power button the mac spins into life for a few seconds and then goes off. Now, at first I assumed the battery was dead so after replacing it and resetting the PMU I have all sorts of weirdness

• At first it booted ok to the flashing folder (there is no disk in there yet)
• I fitted a new HDD. As before, it Does not boot
• Removed the HDD. Does not boot.
• Removed all external cables. Reset PMU again. Does not boot.
• Removed the ram modules. Boots
• Added one module at a time. Does not boot.
• Removed Graphics card. Does not boot
• Put it all back together. Boots
• Switch off and wait a few minutes for a second test. Does not boot.
• Now removed all components, including CPU. Cleaned every piece and refitted. Boots
• Connected HDD. Does not boot.
• Removed HDD. Does not boot.

Seriously....WTF?

Any thoughts from anyone?

 

[eyoungren]

MDDs are notorius for bad PSUs. I would suspect that your removing things reduces power draw enough that the PSU can power on the rest of the stuff and at that point is able to maintain itself.

But over time with everything back in there and a sub-par PSU you get no boot.

I'd try either replacing the PSU or swapping it with a known good one.

 

[Gaeokerena]

Well...

I have been messing with this now for two days. Tonight I gave up and turn it off, but before packing it back in the boxes, I thought I try my luck and the damn thing booted!

I have now managed to install Tiger and have it boot three times in a row now.

I have no idea what this was all about or even if its going to happen again, but thanks for your input eyoungren

 

[eyoungren]

Well...

I have been messing with this now for two days. Tonight I gave up and turn it off, but before packing it back in the boxes, I thought I try my luck and the damn thing booted!

I have now managed to install Tiger and have it boot three times in a row now.

I have no idea what this was all about or even if its going to happen again, but thanks for your input eyoungren

Here is my suggestion…leave it on.

Leave it on and find an inexpensive PSU replacement on eBay. That way if it tanks on you again then you have a backup.

Leaving it on means you can continue using it without driving yourself mad trying to get it to boot.

 

[Gaeokerena]

Thanks for the advice eyoungren

I have also discovered that the internal speaker is dead, but the mac come with pro speakers so all good.

I have a question about the mac's power button though; is it supposed to push all the way in or is it - as it is with mine - almost tough sensitive with only a slight movement?

 

[eyoungren]

Thanks for the advice eyoungren

I have also discovered that the internal speaker is dead, but the mac come with pro speakers so all good.

I have a question about the mac's power button though; is it supposed to push all the way in or is it - as it is with mine - almost tough sensitive with only a slight movement?

IDK. I've never had, nor actually even used an MDD personally. The closest I have every gotten to one is the Quicksilver and the QS only has a short push (not like a PC). Don't know if Apple changed that or not with the MDD.

 

[Dronecatcher]

I have a question about the mac's power button though; is it supposed to push all the way in or is it - as it is with mine - almost tough sensitive with only a slight movement?

I've found them to be variable, some have travel, some as you say a light touch - I had one that was like poking at concrete!

 

[0248294]

I've found them to be variable, some have travel, some as you say a light touch - I had one that was like poking at concrete!

Those power buttons are fairly dodgy. They degrade, and often will be hard to push in. Mine is also quite like concrete, it has to be pushed in on the upper edge of the button, else you can't depress it properly. Figured that out quite quickly when I was attempting to boot it up once I got it, my finger literally was in pain afterwards from prodding it. Good thing all the other PowerMac G4 models have better power buttons...

 

[Dronecatcher]

my finger literally was in pain afterwards from prodding it.

I'm launching a Kickstarter for my G4 Qwikstart Stylus....

 

[eyoungren]

I'm launching a Kickstarter for my G4 Qwikstart Stylus....

View attachment 753440

I'm thinking the 'Atomic Mac'.

Strap Mac to a tacnuke on a timer and run!

 

[Gaeokerena]

Thanks guys, but I think I've given up now.

I was playing on the mac all yesterday for an extensive test....and some Civilisation!

I noticed the CPU was getting hot much quicker than it should so I took the opportunity to clean and apply some new thermal paste.

...and now it won't boot again. Lights. Bong. Off
[doublepost=1520455179][/doublepost]hmm....booted again.

An observation that I've never experienced or read before. The PowerMac only seems to boot if it is left plugged in (and socket switched on) but itself switched off for at least half an hour. It then boots.

Weird!

 

[mode11]

It’s not that weird. It’s a classic symptom of a failing PSU, most likely from faulty capacitors.

And yes, those MDD power buttons can be rock hard.