iMac G5 light sensor problem

[Ih8reno]

I recently bought an iMac g5 1.8ghz 17inch with no hdd in which the seller had told me that before she took out the hd the screen began turning blue. I thought perhaps her hdd was going bad and thought it would be an easy fix. Brought it home and took my hdd from the identical one I already own and connected it and turned it on. The light on the front goes on but the screen stays black and all I hear is a fan. Am I right to assume the logic board is finished? or is there another fix for this.

 

[tigerintank]

when you say it only has a balck screen - has it booted|?

A few random thoughts/q's

do you hear the chime
does it appear on your local network
do you hav an external screen to plug in
since you have an identical model you're in a position to swap hardware - tho others may advise of a risk of damaging a known good part
if you can't get it working then could you return it - after all the screen isn't blue with a known working hdd in

 

[Ih8reno]

Tried booting it and no chime or anything. The fan just comes on after about 30 seconds and then sounds like a vacuum. I swapped the ram and hdd from my other iMac and nothing changed. I haven't tried connecting another monitor however. Bought it for $10 off someone else and I knew it had some problems, just hoped a new hdd would make it boot up again.

 

[Zotaccian]

If it is the first revision those had lots of capacitor problems, if it is the second revisions (ALS) those have ATI which fails more often than the NVIDIA card in first rev. but If I remember corrctly ALS series also had its share of capacitor problems. Symptoms of bad caps range from unstable machine to completely dead machine, these ones in question can be replaced easily (disassembling the machine is bit painful).

There are some diagnostics leds which should lit if all is ok, the red one should not lit (overheat). Try booting without the back cover, google what those leds mean

 

[Ih8reno]

The third one which apparently shows if it is communicating with the LCD isn't lighting up. Gonna do a search on google now but if you have more ideas let me know