Another 10.2 install killed iMac G3

[howardc64]

Got a free iMac G3 350 slot load runnning 10.0. Decided to upgrade to 10.2 and all went smoothly. Then the screen went blank when powered it up next day. The iMac was running judging by the sound of the HDD. Zapped the PRAM and now the iMac powers up, bongs, and shuts off in a few second. No chance to fire up any OS discs or HDDs. Pressing the power button again would only light but green but nothing happens (s4 state). Disconnect power for few seconds (gets back to S1 state) and can repeat this whole sequence. After some research, realized I've walked into the classic 10.2 install without firmware update problem.

A full explanation of what has occurred is in the first post in this link

http://www.capecodgraphics.com/pages/macintosh.html

Basically screen goes blank as 10.2 talking to old firmware sends wrong commands to the video subsystem so screen goes blank. PRAM zap messes up PRAM to the point where PAV board will alert the logic board to shutdown soon after starting. Hence the problem pattern I observe above.

After a bit of google search, tried just about everything simple like removing + reinstall RAM, reset PMU, press/hold programmer button during boot. Leave iMac powered down for awhile, press the power switch for awhile without being plugged in etc. Nothing worked. Always the same failure pattern described above.

The link above also references a way to hotwire the PAV and logic board so the PAV shutoff signal is ignored. Anyone has info on how to do that?

Thanks

 

[z970]

I don't have info on how to do that.

But as a last ditch effort, you could just replace the hard drive and try again with the new firmware.

 

[howardc64]

I don't have info on how to do that.

But as a last ditch effort, you could just replace the hard drive and try again with the new firmware.

thx for the response, I think HDD replacement is no use at the moment as PAV tells logic board to shutdown before anything can get very far. I've had install CDs inside the optical drive and system shuts down while its trying to spin up. HDD basically makes the "power on" noise but never make any more noises as logic board never gets there.

 

[z970]

thx for the response, I think HDD replacement is no use at the moment as PAV tells logic board to shutdown before anything can get very far. I've had install CDs inside the optical drive and system shuts down while its trying to spin up. HDD basically makes the "power on" noise but never make any more noises as logic board never gets there.

Well drat.

I'm all out of ideas.

 

[galgot]

From the link you posted , the guy solved the problem with an external screen plugged, then OpenFirmware, and booting on a OS9 cd.
Maybe you could try plugging an external screen ?

 

[amagichnich]

"So, finally, today, I was about to crack the case and remove its hard drive, when I thought, what the heck, it's good as dead already... why not try one more thing? So, I held down the Programmer's button on the side of the iMac while starting it up.. and bingo! It didn't shut down this time! The screen was black, but it was up and running to some extent. I hooked up a PC monitor to the iMac and saw the Open Firmware screen. This was pretty exciting, until I realized that it was not accepting any input from the keyboard or mouse. What now? I stuck my OS 9.2 CD into the slot, did the "3 finger salute" reboot, held down the C key and prayed harder than I have in a while.... and eureka! The CD booted the iMac successfully! I was able to do a clean install of the OS to upgrade it from 9.0 to 9.2, restart the Mac and then upgrade its firmware."

Have you tried this? Else you know what to do

 

[howardc64]

From the link you posted , the guy solved the problem with an external screen plugged, then OpenFirmware, and booting on a OS9 cd.
Maybe you could try plugging an external screen ?

Mine has no VGA connector and PAV is shutting down the iMac before getting to boot from HDD, launch Open Firmware or OS9 CD.

"So, finally, today, I was about to crack the case and remove its hard drive, when I thought, what the heck, it's good as dead already... why not try one more thing? So, I held down the Programmer's button on the side of the iMac while starting it up.. and bingo! It didn't shut down this time! The screen was black, but it was up and running to some extent. I hooked up a PC monitor to the iMac and saw the Open Firmware screen. This was pretty exciting, until I realized that it was not accepting any input from the keyboard or mouse. What now? I stuck my OS 9.2 CD into the slot, did the "3 finger salute" reboot, held down the C key and prayed harder than I have in a while.... and eureka! The CD booted the iMac successfully! I was able to do a clean install of the OS to upgrade it from 9.0 to 9.2, restart the Mac and then upgrade its firmware."

Have you tried this? Else you know what to do

Yep, held programmer's button during boot multiple times. No dice.

======

Also executed everything from simple to advanced in this following doc on page 7 to beginning of 9 including pulling the video cable. No dice.

http://mrjcd.com/gileskennedy/iMac_firmware_problem_v1_2.pdf

Only thing I didn't do is switch CRT type on PAV board. Not sure if I've got V2 of the board and didn't see a switch.

Anyhow, looking for info on how to hotwire PAV/logic board to stop triggering shutdown.

Thanks

 

[howardc64]

An update. Apparently removing the current memory and putting in a 64MB PC100 DIMM allow the iMac to start again. But through various reboots went back to PAV shutdown. Was able to resume booting again by some combo of removing all memory, boot with no memory, put 64MB in 2nd slot.

Now to rescue video. It appears all the remedy requires a OS9 bootable HDD + remote control app such as Timbuktu + firmware image. Pretty much need another G3 to create an OS9 bootable HDD so will have to wait for that.