Bad Picture quality when AC powered

Hi,

Based on your post/description, your power supply is faulty.
1. It your 24VAC adapter/power supply is the original one that came with the camera, then most likely a component failure inside. More often it is the filter capacitor.
2. If it is a replacement, then possibly the ratings are not compatible with the camera, specifically the current or power (Amps or Watts).
3. In some instances the built-in regulator might be shot since your source is 24 but your load rewuires only 12.

Hope this be of some help/idea. Post back how things turned out or should you need additional information.

Good luck and kind regards.