I picked up a 15” iMac G4 recently for an absolute steal. 10$ since the owner couldn’t get it to boot. When I first got it, I didn’t notice any issues with it at all. It was functionally, just fine.
After tearing it down for cleaning the next day, it then developed an issue. After a bit of running (around a minute) the fans would ramp up, and the mac would freeze. It did this in the boot picker, the screen for not finding any boot media, and even open firmware. For reference, the night before I had it running long enough to NetBoot into a 10.5 installer.
I had replaced the thermal paste both on the CPU die and between the heatsink and metal case when I tore it down, with some MX7, but after removing the heatsink, it did seem a lot of it pumped out. But even after putting some (undeserved) Thermal Grizzly phasesheet, (the stuff I use on my laptops, from a 9980hk, 4910mq, and a C2D T9600, all just fine with this stuff) it still exhibited these issues.
What should I be looking at? This doesn’t get far enough into boot for it to have any temp monitoring, outside of something I could maybe punch into open firmware quickly.
I figure a good thing for diag to have would be the locations of temp sensors on the board as well. If anyone knows what they are, it’d be very useful.
Edit: I got it booting reliably with some effort. The current workaround I have for this, is to first boot into OF, let the fans ramp up (for some reason it's stopped freezing in OF?) then just use the mac-boot command to continue booting. Everything works fine from there, netboot, booting from firewire, and CD. The only thing that doesn't work, is TDM which i figure is because it doesn't have a device assigned to master on the IDE bus, due to a missing hard drive.
I'll try putting this thing through AHT next.
After tearing it down for cleaning the next day, it then developed an issue. After a bit of running (around a minute) the fans would ramp up, and the mac would freeze. It did this in the boot picker, the screen for not finding any boot media, and even open firmware. For reference, the night before I had it running long enough to NetBoot into a 10.5 installer.
I had replaced the thermal paste both on the CPU die and between the heatsink and metal case when I tore it down, with some MX7, but after removing the heatsink, it did seem a lot of it pumped out. But even after putting some (undeserved) Thermal Grizzly phasesheet, (the stuff I use on my laptops, from a 9980hk, 4910mq, and a C2D T9600, all just fine with this stuff) it still exhibited these issues.
What should I be looking at? This doesn’t get far enough into boot for it to have any temp monitoring, outside of something I could maybe punch into open firmware quickly.
I figure a good thing for diag to have would be the locations of temp sensors on the board as well. If anyone knows what they are, it’d be very useful.
Edit: I got it booting reliably with some effort. The current workaround I have for this, is to first boot into OF, let the fans ramp up (for some reason it's stopped freezing in OF?) then just use the mac-boot command to continue booting. Everything works fine from there, netboot, booting from firewire, and CD. The only thing that doesn't work, is TDM which i figure is because it doesn't have a device assigned to master on the IDE bus, due to a missing hard drive.
I'll try putting this thing through AHT next.
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