Bad CRT or video board on iMac

[sisibeans]

This is the problem. The iMac (G3, 400MHz, blueberry) boots fine but the display is a deep purple and very high contrast. Just about impossible to make out anything on the screen.
What could be going on? Bad CRT or video board? How would I go about diagnosing the problem?

Thanks for any help with this.

[ElDiabloConCaca]

I remember something like this happening if you didn't install an iMac G3 firmware upgrade before installing some flavor of OS X.

Does this sound like something you're experiencing:
http://www.macintouch.com/panfirmware.html ?

[sisibeans]

Thanks diablo. The link was very helpful. I now suspect that the video board is deffective. eBay has a few listings for these boards. How difficult would be to replace the video board? Are there instructions on how to crack the iMac and replace the board?

Regards

[bobw]

You can download a Service Manual for your machine HERE

[sisibeans]

Thanks Bob. Great manual!!