PowerMac G4 won't turn on with Cinema HD Display connected.

Well with some more faffing around getting OS X to boot (seems I needed to do a PMU reset again because I'd pulled the cd drive out), I got in, and looked at the system log, as well as all messages log. Can't say there's anything there that stands out to me. The all messages log dates back months and just seems to say "shut down this start up that" but no errors or what have you. The system.log on the other hand only has one line in it that stands out to me (highlighted in bold):

Jan 1 01:00:50 localhost kernel[0]: Copyright (c) 1982, 1986, 1989, 1991, 1993

Jan 1 01:00:50 localhost kernel[0]: The Regents of the University of California. All rights reserved.

Jan 1 01:00:50 localhost kernel[0]: MAC Framework successfully initialized

Jan 1 01:00:50 localhost kernel[0]: using 10485 buffer headers and 4096 cluster IO buffer headers

Jan 1 01:00:50 localhost kernel[0]: AirPort_Brcm43xx::probe: 02e5da80, 0

Jan 1 01:00:50 localhost kernel[0]: FireWire (OHCI) Apple ID 31 built-in now active, GUID 000a95fffee934be; max speed s400.

Jan 1 01:00:50 localhost kernel[0]: ApplePMU - vers. 126 download complete -

Jan 1 01:00:50 localhost kernel[0]: ApplePMU::CLOCK RESET! PMU WAS PROBABLY RESET SOMEHOW!!

Jan 1 01:00:50 localhost kernel[0]: mbinit: done

Jan 1 01:00:50 localhost kernel[0]: Security auditing service present

Jan 1 01:00:50 localhost kernel[0]: BSM auditing present

Jan 1 01:00:50 localhost kernel[0]: rooting via boot-uuid from /chosen: 65EA8C78-5A7B-38A5-A7DF-D5CF93871511

Jan 1 01:00:50 localhost kernel[0]: Waiting on <dict ID="0"><key>IOProviderClass</key><string ID="1">IOResources</string><key>IOResourceMatch</key><string ID="2">boot-uuid-media</string></dict>

Jan 1 01:00:50 localhost kernel[0]: wl0: Broadcom BCM4320 802.11 Wireless Controller

Jan 1 01:00:50 localhost kernel[0]: 4.170.25.8.2Got boot device = IOService:/MacRISC2PE/pci@f4000000/AppleMacRiscPCI/ata-6@D/AppleKauaiATA/ATADev iceNub@0/AppleATADiskDriver/IOATABlockStorageDevice/IOBlockStorageDriver/IBM-IC3 5L090AVV207-0 IBM-IC35L090AVV207-0/IOApplePartitionScheme/Apple_HFS_Untitled_2@10

Jan 1 01:00:50 localhost kernel[0]: BSD root: disk0s10, major 14, minor 9

Jan 1 01:00:50 localhost kernel[0]: Jettisoning kernel linker.

Jan 1 01:00:50 localhost kernel[0]: Resetting IOCatalogue.

Jan 1 01:00:50 localhost kernel[0]: Matching service count = 1

Jan 1 01:00:50 localhost kernel[0]: Matching service count = 3

Jan 1 01:00:50: --- last message repeated 4 times ---

Jan 1 01:00:50 localhost kernel[0]: Matching service count = 6

Jan 1 01:00:50 localhost kernel[0]: PowerMac3,6: stalling for module

Jan 1 01:00:50 localhost kernel[0]: rtclock timebase_callback: late old 1000000000 / 41656790 new 1000000000 / 41656700

Jan 1 01:00:50 localhost kernel[0]: rtclock timebase_callback: late old 1000000000 / 41656790 new 1000000000 / 41656610

Jan 1 01:00:50 localhost kernel[0]: rtclock timebase_callback: late old 1000000000 / 41656790 new 1000000000 / 41656700

Jan 1 01:00:50 localhost kernel[0]: Matching service count = 1

Jan 1 01:00:54 localhost bootlog[37]: BOOT_TIME: 0 0

Jan 1 01:00:55 localhost DirectoryService[33]: Launched version 5.8.1 (v514.28)

Jan 1 01:00:55 localhost rpc.statd[19]: statd.notify - no notifications needed

Jan 1 01:00:55 localhost fseventsd[28]: bumping event counter to: 0x27ea20 (current 0x0) from log file '000000000027db60'

Jan 1 01:00:55 localhost /System/Library/CoreServices/loginwindow.app/Contents/MacOS/loginwindow[24]: Login Window Application Started -- Threaded auth

Jan 1 01:00:56 localhost DumpPanic[31]: Panic data written to /Library/Logs/PanicReporter/1970-01-01-010056.panic

Jan 1 01:00:56 localhost kernel[0]: UniNEnet: Ethernet address 00:0a:95:e9:34:be

Jan 1 01:00:56 localhost kernel[0]: AirPort_Brcm43xx: Ethernet address 00:16:41:78:6f:a4

Jan 1 01:00:58 localhost kernel[0]: AirPort: Link Down on en1

Jan 1 01:00:58 localhost com.apple.launchd[1] (com.apple.aslmanager): Throttling respawn: Will start in 5 seconds

It appears there was a kernel panic? The log's quite long incidentally so I've truncated it somewhat but before the first line it was mostly just waffling away about loading modules and things and after the last line it was waffling away about the wifi and so on so I don't think they were relevant. I didn't notice anything wrong though while it was booting (I mean, it didn't show me any errors or anything and I always assumed if there was a kernel panic it actually throws it up in your face).

The date being reset was down to me pressing the PMU button. It also hasn't panicked since that first time either, but here's what the panic log says anyway:

Thu Jan 1 01:00:56 1970

panic(cpu 0 caller 0x000B0504): "Uncorrectable machine check: pc = 0000000000913F30, msr = 0000000000149030, dsisr = 40000000, dar = 000000003B372FF8\n" " AsyncSrc = 0000000000000000, CoreFIR = 0000000000000000\n" " L2FIR = 0000000000000000, BusFir = 0000000000000000\n"@/SourceCac

he/xnu/xnu-1228.15.4/osfmk/ppc/trap.c:975
Latest stack backtrace for cpu 0:
Backtrace:
0x0009CC88 0x0009D63C 0x00029DA0 0x000B0504 0x000B0784 0x000B4278
Proceeding back via exception chain:
Exception state (sv=0xd03500)
PC=0x00913F30; MSR=0x00149030; DAR=0x3B372FF8; DSISR=0x40000000; LR=0x00913ECC; R1=0x356179A0; XCP=0x00000008 (0x200 - Machine check)
Backtrace:
0x00913ECC 0x009148C4 0x00915308 0x0094A6A0 0x009077E4 0x00907CBC
0x00348ED8 0x0034A02C 0x0034BEDC 0x0034AFFC 0x000B1DD4
Kernel loadable modules in backtrace (with dependencies):
com.apple.driver.AirPortBrcm43xx(367.91.22)@0x8fd000->0xa29fff
dependency: com.apple.iokit.IO80211Family(216.1)@0x8d9000
dependency: com.apple.iokit.IOPCIFamily(2.6)@0x5c7000
dependency: com.apple.iokit.IONetworkingFamily(1.6.1)@0x883000
Exception state (sv=0x2f5a9500)
PC=0x00000000; MSR=0x0000D030; DAR=0x00000000; DSISR=0x00000000; LR=0x00000000; R1=0x00000000; XCP=0x00000000 (Unknown)

BSD process name corresponding to current thread: kernel_task

Mac OS version:
Not yet set

Kernel version:
Darwin Kernel Version 9.8.0: Wed Jul 15 16:57:01 PDT 2009; root:xnu-1228.15.4~1/RELEASE_PPC
System model name: PowerMac3,6

System uptime in nanoseconds: 54277116529
unloaded kexts:
(none)
loaded kexts:
com.apple.driver.AppleFileSystemDriver 1.1.0 - last loaded 2260802838
com.apple.iokit.IOUSBHIDDriver 3.4.6
com.apple.driver.AppleUSBMergeNub 3.5.2
com.apple.driver.AppleUSBHub 3.4.9
com.apple.iokit.IOUSBUserClient 3.5.2
com.apple.driver.XsanFilter 2.7.91
com.apple.iokit.IOATABlockStorage 2.0.6
com.apple.driver.ApplePMU 2.5.6d2
com.apple.driver.AppleVIA 1.5.1d1
com.apple.driver.AppleGPIO 1.3.0d0
com.apple.driver.AppleCPUThermo 2.0.0a0
com.apple.iokit.AppleMediaBay 1.0.2f1
com.apple.driver.KeyLargoATA 1.1.1f1
com.apple.driver.AppleI2C 4.0.0d2
com.apple.driver.MacIOGPIO 1.3.0d0
com.apple.driver.AppleMPIC 1.5.3
com.apple.iokit.AppleGMACEthernet 1.5.9f1
com.apple.driver.AppleFWOHCI 3.9.7
com.apple.driver.AppleKauaiATA 1.2.1f4
com.apple.driver.AppleUSBOHCI 3.4.6
com.apple.driver.AirPortBrcm43xx 367.91.22
com.apple.driver.AppleKeyLargo 1.7.2f1
com.apple.driver.AppleMacRiscPCI 3.4.0
com.apple.driver.AppleCore99NVRAM 1.1.1
com.apple.security.seatbelt 107.12
com.apple.nke.applicationfirewall 1.8.77
com.apple.security.TMSafetyNet 3
com.apple.BootCache 30.4
com.apple.driver.DiskImages 199
com.apple.driver.AppleMacRISC2PE 1.8.7d5
com.apple.driver.AppleUSBComposite 3.2.0
com.apple.iokit.IOFireWireFamily 3.4.9
com.apple.iokit.IOATAFamily 2.0.1
com.apple.iokit.IOUSBFamily 3.5.2
com.apple.iokit.IO80211Family 216.1
com.apple.iokit.IONetwop

Well, no I haven't, I've already tried removing non essential hardware like the airport card (it's not an airport card in reality but a third party compatible wifi PCI card) and trying to power-on the Mac with the monitor plugged in and the issue persists. This kernel panic was a red herring, it only occurred the one time and more than likely because I'd reset the PMU.

Not that I can see. Though I really don't know exactly what to look for though, but there doesn't appear to be any errors or oddities in any of the logs beyond that one initial panic. I don't think OS X is picking up on the problem whatever it is, probably because even when I "trick" the Mac into power up by itself by pulling the ADC monitor out and plugging it back in, it boots to open firmware first of course and when I type mac-boot then it loads OS X as normal, so to me it would seem OS X isn't "seeing" whatever the issue is because by the time it boots the Mac is already running as it should be, if you catch my drift.

I've tried yanking out everything except for the monitor (and by extension the graphics card) and it still won't turn on with the monitor plugged in so I'm pretty sure that rules out everything except the PSU, the Logic board, the CPU or the monitor itself (as stated before I've tried a different graphics card and the same issue occurs so it isn't that either and this is a different monitor, so unless they both have the exact same issue I don't think it's that either).

Thanks for your help so far by the way. Appreciate it.

Well I did all three from open firmware and apart from resetting the clock again it hasn't fixed the problem; once shut down, it still won't turn on by pressing the button on the Mac or the monitor. I've tried resetting the nvram using the keyboard startup keys before, but did it again after restarting the Mac from inside OS X and nothing was fixed.

Plugged the old monitor with a flash light in hand, but the Mac powered up when I pressed the button, and the screen turned on and showed OS X.So that monitor works too, though I expect the problem I had with it where it would randomly turn off almost as if it had no power will show up eventually - it was very random. After I first noticed it started doing it, sometimes it would happen after an hour or so of use or sometimes it'd happen 30 seconds after start up.Other times I'd been able to use the machine for a few hours without it doing it once.

Well the screen conked out a few seconds after OS X booted this second time (that first time I tried it was working for several minutes until I shut the Mac down). Did what you suggested and shone the torch into the screen at all sorts of angles and at different points but I can't see the desktop.