Every home in Wales should have a digital television signal by March 2010
The digital switchover in Wales is continuing with signals to Denbighshire and Flintshire changing.
Analogue BBC Two was switched off at the Moel y Parc transmitter, serving north east Wales, at midnight.
A stronger digital signal was switched on instead, allowing some 85,000 viewers to receive a digital signal via relay transmitters for the first time.
The remaining analogue signals are to return on Wednesday but are switched off permanently on 25 November.
Freeview viewers using the transmitter and its relays will need to retune to find some channels.
Every home in Wales should be digital by March 2010. Digital UK says 90% of homes in Wales already have digital TV.
Digital UK said terrestrial television services in north east Wales will be off air for some viewers until the first stage of switchover is completed by around mid afternoon on Wednesday.
Freeview, BT Vision and Top Up TV should retune their equipment once services are back on air.
On 25 November, the second stage of the switchover takes places when the remaining analogue channels are switched off permanently.
Relay transmitters will offer further Freeview channels from ITV, S4C, Channel 4 and Five for the first time.
Emyr Byron Hughes, the national manager for Wales for Digital UK, said: "Switchover means many people can receive Freeview channels for the first time.
"We're encouraging viewers who still don't have the necessary equipment to get ready in time for 25 November, when all the analogue channels will be permanently switched off.
"Anyone who needs advice during this period should contact Digital UK."
Digital TVs or analogue sets converted with a digital box will be able to receive BBC One, BBC Two, ITV1, S4C and Five, plus additional digital channels such as BBC Three, BBC Four, BBC News, ITV2, More 4 and digital text and radio services.
Swansea was the first city in Wales to go totally digital when the analogue television signal was completely turned off in September.