is my ImacDV 400s motherboard really dead?

[claudiodeviaje]

Hi Everyone!!!

I'm having Problems with my Imac Indigo DV400, I'm not really sure but I think its a summer 2000 model (anyway all DV are the same acording to the manual) .

The problem is that it won't start up..... The power LED just lights green and the HDD make some noises but nothing else. I don't get image in the monitor nor I hear the startup sound.... in sumary I won't boot!!!!!

I got the service manual in the internet and tried everything what I read there.
I changed the battery for a new one. I reseted the PRAM and the Open Firmware and CUDA, I changed the RAM .... but nothing happened.

I took the dust off my multimeter, open the Imac and measured everything posible (acording to the manual), and I got the following:

Battery voltage: 3,61v
Trickle voltage at J9: 4,8v
Downconverter voltage at pin 2: 11,9v
pin 4: 4,9v
pin 14: 3,3v
Fuse in PAV board (F901) is ok.
CDO Voltage in C10 (motherboard) with the computer off: -1,1v
CDO voltage in C10 with the computer ON: 24,8v !!!!!!!!!!

All values are ok, except for the last one. According to the service manual I should get +21v but I'm getting +24,8v. I don't really know if this difference is within spec, but I thought I might just ask.

Does this means that the motherboard is fried?
If this 24,8 are withing specs, What could be causing this problem?

Is there something else I could do in order to bring it back to life?



When I turn the imac on WITHOUT Ram I get one beep.....And if I hook an external monitor I get nothing no image....

Thanks!

 

[DaveGoTech]

Did anyone try updating to OS/X right before this happened? If the PRAM was not updated first, or done incorrectly, it causes this problem. Another possibility is a corrupted hard disk. Try booting from CD (original O/S) and see if it boots.