what would cause this?

It's almost certainly a board-level problem with the analogue video circuitry. I'm far from the most knowledgeable here about these things, but from my Color Classic modding experience I'd say a failing (or failed) component on the main video board is resulting in insufficient voltage being sent to whatever controls the projection of the horizontal width of the display.

Others more expert than me will have to tell you whether this can be fixed, or if it requires total replacement of the analogue board.

Best,

Matt

That's not quite the same as what my iMac DV was doing, but mine turned out to be a MB problem.

Have you tried an external monitor, and if so, what result?

Finally, if you think it might be the PAV board, I have a good one that would go pretty cheaply.

Tmtomh's on the right track. I think that you will find that it's just a flaky solder joint or poor connector. Your problem of insufficient width means that the horizontal deflection is weak. However, that circuit is intimately coupled with the high-voltage circuitry. The fact that the focus is reasonably good (at least as far as I could tell from the pic), and that the height is more or less correct, indicates that your HV circuitry is ok. That, in turn, implies that the basic horizontal deflection circuits are probably ok, too. That leaves a bad connection as the most likely possibility. There are others, too, but don't worry about that just yet.

I've heard that this problem is quite common with iMacs stored upside down, no idea why. Tmtomh is on the right track here, try out an external monitor and see what happens. If it works fine with external, suspect analog board. If it doesn't, suspect motherboard.

All CRT monitors have problems when stored upside down.

rly?

why?

They have problems of turned on upside down, methinks.

External Monitor works great. I was just wonder what would cause this. I am not really looking into fixing it. But let me know if anyone wants parts from it

I can't see the photo, I simply get your index page, with no CSS.

Dude! how much ram you have in there?

apparantly 1 gig ( i went to his site posted in conquests)

IIRC storing CRT monitors upside down puts stress on the top part of the case which isn't designed to take load, which in turn causes it to twist. That moves the internal components, and can stress those too which can crack any brittle solder joints on the circuit boards. It's not Voodoo, just simple mechanics

Voodoo is better and easier to understand though.

Pfftt, whatever. Since when does 'put weight on weak spot, weak spot bends, internals bend with it, stuff breaks' not make sense?

I'm just going away to stab pins in an effigy if anyone needs me...