2nd monitor keeps blanking out.

[GavinBKK]

I bought a Samsung SyncMaster S23B550 to go with my existing Samsung E2020 on a newly purchased Mac Mini. The E2020 is connected to the Mini from the Thunderbolt port, using the Mini-DVI adapter and functions normally.

The S23B55 is connected to the Mini with a separately purchased HDMI cable.

Here in provincial Thailand, voltage can be variable. When I hear the aircon unit click (is this a voltage drop?) the S23 screen blanks out briefly. The E2020 is fine. At first, I thought this was an issue of drawing too much current from the socket, so I connected the S23 to the UPS. No change. Still blanks out when the aircon clicks. Got a sparks to come and fit additional plug sockets, wired direct from the fuse panel and powered the S23 direct from there. No change, the S23 still blanks out when the aircon clicks. Just to add some spice, the S23 will occasionally blank out without the aircon clicking!

Has anyone got any idea what is happening and why??

TIA