Looking for Atari SC1224 monitor schematic - test-drb@ccmp.vtda.org

20 Apr 2004

At 23:49 20/04/2004 +0100, you wrote:
...
   Anyway, the
machine itself works fine, however the Atari SC1224 monitor that
 came with it does not. I can hear it "chirp" when I throw the switch,
suggesting 
What sort of power supply does it use? If it's a switcher, then the chirp 
might be coming from the chopper transformer, indicating, perhaps, a 
short on the output of the PSU. That, in turn, might be the line output 
transistor (HOT to you, I guess). 
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
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.

This is where a set of schematics would really help (anyone ???)

Regards,
-- 
dave04a (at)    Dave Dunfield
dunfield (dot)  Firmware development services & tools: www.dunfield.com
com             Vintage computing equipment collector.
                http://www.parse.com/~ddunfield/museum/index.html