aapl2c
Member
Hello!
I have a strange failure. One of my Quadra 700 systems won’t boot, turns on but no boot beep, no video, doesn’t try to boot off floppy/SCSI. It behaves the same when all RAM/VRAM is removed and when trying with a different known good CPU or power supply. The board is in very good shape and I don’t see any obvious physical issues on it.
On a whim, I decided to try an Apple PowerPC upgrade card in it, and it booted right away, playing the PPC boot chime (that card had never been installed in this system). It continues to boot and seemingly work fine if that PPC card is installed…
Since the PPC card has it’s own ROMs on it, I’m guessing there may be some issue with the ROMs on this system (no idea why though).
My understanding is that this system will either use the onboard ROMs or automatically switch to ROMs in the ROM SIMM slot if one is installed. So just for kicks, I installed the ROM SIMM from a IIsi to see what it’d do - it behaved like before, no boot beep/no video/etc. I didn’t expect it’d boot, but was hoping it’d at least play the boot crash chime or something.
Anyone ever hear of a problem like this? I have checked voltages while the system is running in the bad state (seems to be ok) and have probed about with a logic probe and it seems like there's activity on the ROM chips, other places. I'm curious if anyone has more info on what parts of this system controls that ROM muxing (I'm not aware of any schematics available for this)
Thanks!
I have a strange failure. One of my Quadra 700 systems won’t boot, turns on but no boot beep, no video, doesn’t try to boot off floppy/SCSI. It behaves the same when all RAM/VRAM is removed and when trying with a different known good CPU or power supply. The board is in very good shape and I don’t see any obvious physical issues on it.
On a whim, I decided to try an Apple PowerPC upgrade card in it, and it booted right away, playing the PPC boot chime (that card had never been installed in this system). It continues to boot and seemingly work fine if that PPC card is installed…
Since the PPC card has it’s own ROMs on it, I’m guessing there may be some issue with the ROMs on this system (no idea why though).
My understanding is that this system will either use the onboard ROMs or automatically switch to ROMs in the ROM SIMM slot if one is installed. So just for kicks, I installed the ROM SIMM from a IIsi to see what it’d do - it behaved like before, no boot beep/no video/etc. I didn’t expect it’d boot, but was hoping it’d at least play the boot crash chime or something.
Anyone ever hear of a problem like this? I have checked voltages while the system is running in the bad state (seems to be ok) and have probed about with a logic probe and it seems like there's activity on the ROM chips, other places. I'm curious if anyone has more info on what parts of this system controls that ROM muxing (I'm not aware of any schematics available for this)
Thanks!