Hello, new user and I have a question

2 replies [Last post]
Joined: Feb 14 2007
Posts: 2


Maybe someone might be able to help? At work I have an Apple iMac 15" 700MHz "Lamp". The problem I am having with it is the lcd backlight does not come on, the drives do not spin up, and the fan does not spin. When I press power I hear the Boooong sound and I can see by reflection only the finder faces and alternating question mark in the lcd panel.

Replacing the power supply with a brand new one from welovemacs.com did not help, much to the irritation of my boss Sad I also reset the PMU which did not help either. The battery measures voltage of about 3.65v. When I tested the molex connector that I disconnected from the cd-rom drive, I am getting +5v on the red lead and nothing on the yellow lead.

I tested the hard drive and the cd rom drive on a Compaq Evo that I have here and they both work perfectly.

Any thoughts?

Would be appreciated!


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Dr. Webster's picture
Joined: Dec 19 2003
Posts: 1688
Sounds like you have two prob

Sounds like you have two problems: your LCD backlight is dead, and you're missing your +12V line (you should get 12 volts on the yellow wire you tested). Did you test the new power supply you bought?


Applefritter Admin

Joined: Feb 14 2007
Posts: 2
I did actually test the new p

I did actually test the new power supply as well, and oddly enough it behaved exactly as the old one did. +5v on red, nothing on yellow. I am thinking that something has gone horribly wrong with the logic board or the PMU circuitry Sad

If I had known two weeks ago what I know now about the way Macs work, I would not have been so quick to order a new power supply. I am really very new to Macs, but I have been working on PCs for some years now. I have had similar problems in PC power supplies where one of the rails fails (heh) usually the +12v.. replacement of the unit fixed it and that was that.

So as an aside I will ramble further and say that I bought my first very own mac recently. I went to craigslist and picked up a unit in chicago last week. It is a B&W G3 400MHz with a rev 2 motherboard (the seller made it a point to tell me that). It was configured with 192MB ram and a 12GB hdd. It also had a SCSI card installed in one of the PCI slots, which looked lonely so I removed the 12GB ATA drive and installed a Quantum Atlas 36GB SCSI HDD, and installed 512MB more of SDRAM bringing it up to 704MB. I also threw in a CDRW/DVD combo drive to replace the 24x cd rom.

The machine (plus keyboard and puck mouse) was $100, the extra RAM was $72, and I had the other components. I think I did pretty good!

Now I have to find a copy of OSX Tiger and I'll be all set with a slow mac lol But it will let me poke around in OSX and get a feel for how things work, and try out some software, etc..