Looking for Atari SC1224 monitor schematic

From: Tony Duell <ard_at_p850ug1.demon.co.uk>
Date: Tue Apr 20 23:26:58 2004

> Hi Tony,
>
> It would appear that you are correct. Once I removed the cover, I could clearly
> tell that the "chirp" is coming from the switching power supply. There appears
> to be no activity from the rest of the monitor, including the fact that even
> with the lights off, I could not observe filaments lighting. The power LED does

It's not unheard-of for the CRT heater to run off the flyback
transformer. So if the horizontal output stage is dead, there will be no
heater glow.

> light, however it's fairly dim - I don't know how brightly it would normally
> light.
>
> The final filter capacitor in the supply is rated at 180v DC. I powered the
> supply briefly under no-load and the output rose to 140v. With all the
> connections in place, it is producing about 55v - I have no idea what the
> normal requirements of the monitor are.

I would guess around twice that voltage at least. Does the PSU have one
output or seceral ? Have you checked if any of them are stuck at 0V?

-tony
Received on Tue Apr 20 2004 - 23:26:58 BST