Need some advice regarding a Rev B. iMac

Posted by: Josh K

Need some advice regarding a Rev B. iMac - 02/25/05 12:23 PM

Alright here are the specs. I have a Rev. B iMac that's been upgraded with a Harmoni card, a 40GB HD, and has about 384 MB of RAM. It's running Panther and for basic functions it's still a great computer. Here's my problem:

Recently the screen is slow to come on/doesn't come on at startup. I STFFs and found a lot of talk about the a/v board and how it can go bad. What I've noticed is that unplugging and replugging the USB hub sometimes makes it work. Is this normal? Does that still mean this part is bad?

If so and the CRT will only work by replacing it, I'd rather go about putting a flat LCD in the iMac case a la the iPc mod on this forum. What exactly would I need to do this mod (power supply, etc.) Thanks!
Posted by: krusher117

Re:Need some advice regarding a Rev B. iMac - 02/25/05 12:28 PM

when it does come on, is it dim? I have a monitor with simliar symptons.
it COULD be a flyback, I'm sure whitlock will be responding to this with a more knowledgeable answer
Posted by: whitlock

Re:Need some advice regarding a Rev B. iMac - 02/25/05 12:39 PM

Very peculiar, especially with the USB issue, since they are on different components alltogether. If doing the USB trick makes it work, I may lean a little more towards the logic board at this point. I do have a few questions though

1. When you hit the power button, do you hear the display hit high watt (that monitor thud)?

2. When you upgraded to Panther, did you run the firmware upgrade on the board?

3. Since it is capable, and you have a Rev. B iMac, have you tried hooking up a 15-pin DBA to VGA display adaptor so you can see if the board is putting out display when this occurs?

Such odd symptoms. If you can get more info up, I'll rack my brain on it, but make sure you go through that troubleshooting first. If the video flakes out on an external display, then you have logic board issues. So, pretty much, if your answer is "yes" to all of this, then you probably are looking at the analog board.