MDD DP G4 elusive diagnosis - freezes during boot up. Tired… HELP!

Thanks, Texas Mac Man, but that link appears to lead to the generic support portal. 😟

Thank you, Tom and BDAqua.

Well, I found the CUDA or (PUM reset), and I pressed it once as per the instructions.

No luck. It started fine, the grey apple with the spinning radian appeared to be running normally for 10 or 15 seconds (maybe 20), then it went to a very pale-blueish screen and it froze there.

Maybe it is the battery after all? But then how come it boots just fine in Target Mode? Even to the point of completing the boot process on the G5 Quad when connected to it in Target Mode?

Most puzzling!

Thank goodnes I'm not preoccupied with saving any data or anything else on that drive.

Thanks, BDAqua, you posted while I was composing my reply to Tom's post; but I managed to squeeze in a thank you to yoo too.

Even though re-setting the PUM had no effect, I thought I'd leave the illustration here, just in case someone is looking for that tiny part on this computer at some future date, because none of the links above had anything resembling the logic board of my Dual Bootable, Dual Processor 1.25 GHz MDD G4, made in April of 2004.

Hardware Overview:

Machine Name: Power Mac G4

Machine Model: PowerMac3,6

CPU Type: PowerPC G4 (3.3)

Number Of CPUs: 2

CPU Speed: 1.25 GHz

L2 Cache (per CPU): 256 KB

L3 Cache (per CPU): 2 MB

Memory: 2 GB

Bus Speed: 167 MHz

Boot ROM Version: 4.4.8f2

Any further ideas?

I really want to save this machine because it's the most advanced Mac that can boot straight into native Mac OS 9.2.2 I've got. 😢

Thanks for sticking with me, BDAqua. I'm grateful for the tenacity and persistence you have shown on this forum throughout the years.

If the RAM is not involved in any way in the machine booting up in Target Mode, then I suppose it could be the RAM. Unfortunately, I have no way of testing it now, at least not until I can manage to get at least one the two optical drives. 😟

That's another thing that has me puzzled, why I haven't been able to open the optical drives. Even a longish, strong paper clip doesn't feel like it's hitting anything or meeting any resistance when I insert it through any of the visible openings of the drives. 😮 😕 😢

I don't understand how bad or improperly set RAM could jam both drives even physically.

My next course of action is going to be to pull out the flashed nVidia GeForce 7800 GS 425MHz 256 MB "mutant" flashed graphics display card and install the original video card that came with the G4 Quad.

That there's now a valid OS on the HD is proven by the machine being able to boot up even the G5 Quad when in Target Mode.

Just in case the battery is somehow involved, I've ordered fresh batteries online, as they are a third of the price at the local Radio Shack.

As I said, I'm fortunate that I have the G5 Quad as my main working machine, as well as a working MacBook with Snow Leopard 10.6.8, and that I'm not concerned with saving any data or anything like that.

If you or anybody else has any other thoughts, I'm all ears.

Thanks again

Thank you, japamac, those are all sound suggestions.

I have taken out the graphics card and re-seated it, but I do also have a couple of SCSI PCI cards that I had not thought of re-seating. I'll do that now, and I will reseat all four RAM modules.

I have hopes that exchanging the graphics card for the original one will help. I have a vague recollection of having to replace a kext file for a custom one when I installed the flashed card years ago, after which the PRAM had to be zapped. Glad I kept the original graphics card.

The ATA connectors on the drives hadn't crossed my mind. Great suggestion too!

After that, reseat the processor.

Can you clarify, please? Are you referencing the actual CPU? 😕 I've never re-seated one, except for the G4 ZIF upgrade in my Beige G3 Mini Tower. 😮

Regarding the paperclip push, if slightly out of alignment, the area to push and move the mechanism can be easily missed.

Rebend the clip or reapproach the push.....

Will do. If it's out of alignment it must have been bent out of alignment into the next county, because there's enough room there to move the clip around without it meeting any kind of object I can feel at all, and it's at least 7.5 inches long. 😝

Thank you once again. 🙂

Another thought to throw into the mix: Not too long ago, I uninstalled the two larger internal (IDE/PATA) hard drives from the two front bays to stick them in external FireWire enclosures for use with the Quad and the MacBook. I wonder if I was supposed to have done something about jumpering the two remaining 160 GB drives in the back bay? ?? 😕

Ouch! 😮

I'm afraid all of that's beyond me. 😟

I'm useless when it comes to hardware, really. 😊

No way am I even going to attempt the CPU reseating, with thermal paste, etc. I'm not even sure I understand the first instruction to "jump all hard drives Cable Select and place the intended Master on the end connector of each IDE ribbon (each bus)." I'm just going to have to find a local tech willing to work on a G4.

Thanks for all your help in any event, japamac.