|To change DST requires the information need to be stored internally which is quite a lot for all the different times zones and it is information that is likely to change. It also requires some processing to calculate the necessary dates as the changes take place on a different date each year. |
Another way is to reference an external source such as a TV tuner. Does this video recorder have an analogue TV Tuner that is no longer operational. If this is the case you will have to change the time manually as I have to do with mine,
If you have a digital tuner, makes sure that the tuner is correctly set up. There were some changes recently to UK digital TV channels.