iMac G3 (Bondi-blue 233MHz tray loader) screen stays dark after firmware upgrade

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iMac G3 (Bondi-blue 233MHz tray loader) screen stays dark after firmware upgrade

I've recently had the opportunity to play around a bit with a tray-loading iMac G3 (233 MHz model), and after a quick and painless RAM upgrade I decided to try to install OSX 10.2, where I neglected to perform the firmware upgrade prior to OS install. I'm aware that there are some issues with the later slot-loading models and the screen timing being borked on OSX, but this seems to be a different issue: OSX 10.2 worked fine, with the exception of the system booting to OpenFirmware needing the "mac-boot" command to load the OS.

However, after learning that a firmware upgrade was available I deciced to perform it anyway to prevent any further issues. To do this I re-installed the factory-shipped Mac OS 8.5, which worked perfectly. Afterwards I performed the firmware upgrade and everything seemed to go well, up to and including a progress bar being displayed upon reboot. After the second reboot the screen went dark and hasn't been able to turn on.

If I try to boot the machine disk access sounds can be heard, like during a normal boot, with the exception of the monitor staying dark, with the monitor display light likewise staying red.

Some other possibly important points:

The firmware upgrade was performed with the Real-time clock battery removed, due to it being flat and waiting on a replacement. Could this cause the firmware corruption?
No VGA port available to connect a second monitor
The screen went black exactly after the firmware upgrade supposedly completed, which leads me to rule out a hardware failure. Is this a reasonable assumption?
The power-on bong can be heard and the machine otherwise appears to behave correctly apart from the screen staying black (disk access sounds, is able to stay on indefinitely)
Connecting a Mac LC monitor to the display output doesn't result in an image on the screen.

I have a 160GB IDE hard-drive laying around, if it could be useful.

From what I've read in these early models the firmware is actually stored in a chip on the detachable CPU card. If that's the case, could a CPU card replacement resolve the issue? If not, could it be helped by replacing the logic board and/or any other components?

This seems to be a different issue to the one slot-loaders have with OSX.

Thank you for any help!

iMac, Mac OS 8.6 or Earlier, Tray-loader 233 MHz Bondi-blue

Posted on Dec 25, 2015 2:37 AM

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Answer 1

rccharles

Level 6

12,957 points

Dec 27, 2015 12:15 PM in response to Fabri91

I had not heard of this problem with the G3 iMac tray loaders.

Reset any one? I'd try the pram reset. Lots off people suggest a new pram battery.

Resetting your Mac's PRAM and NVRAM

http://support.apple.com/kb/HT1379

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reset the PMU

http://mrjcd.com/junk/PMU.jpg

http://support.apple.com/kb/ht1939

Sometimes if volumes don't appear in Startup Manager (what you get when you hold down the Option key at startup), you need to reset the Mac's PRAM, NVRAM, and Open Firmware. Shut down the Mac, then power it up, and before the screen lights up, quickly hold down the Command, Option, P, and R keys, until the Mac has chimed twice more after the powerup chime.

Then, before the screen lights up, hold down Command-Option-O-F until the Open Firmware screen appears. Then enter these lines, pressing Return after each one:

reset-nvram

set-defaults

reset-all

"The reset-all command should restart your Mac. If so, you have successfully reset the Open Firmware settings."

http://support.apple.com/kb/TS1812?viewlocale=en_US

Should the fail...

Try taking the battery out for 10 minutes. Put battery back in. Cross fingers. Power the machine back on.

How to eject a cd from the internal cd drive:

eject cd

List of devices:

devalias

List of variables:

printenv

More than you ever wanted to know about open firmware

http://www.firmworks.com/QuickRef.html

( nvram is the equivalent Mac OS X terminal command. )

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Answer 2

Fabri91 Author

Level 1

0 points

Dec 27, 2015 1:32 PM in response to rccharles

Already tried that, no joy, including a new battery. I've now ordered a new CPU board after confirming that the firmware is indeed stored on it and we'll see if it helps. Due to an external monitor also being unresponsive the issue must lie upstream of the monitor, namely either on the CPU board or on the logic board.

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