vestel 17mb25 - "No Signal"

[Quit]

I have one of these chassis, in the form of a Oki V19a, which is now up and running after an eeprom change, but shows the "No Signal" 5 minute countdown.. even though there's a perfectly good DTV picture showing underneath this message 

We don't have analogue channels here anymore - is this model really so stupid it's looking for an analogue TV signal even when showing Digital??

There doesn't seem to be any obvious option to turn off this timer in the user or service menus.