Some Grundig model have a well known Poser Supply fault that causes exactly the problem that you describe. If you can solder (IT IS SKILL that can't be picked up in five minutes.) it is possible to repair the PSU by replacing all the capacitors in it for ones with higher ratings.
Alternatively I believe that Sky will swap your box out for a recon for about £65.
You can use your Sky card in any Sky branded box. If you have premium channels (Sports and Movies) you need to get Sky to 'Pair' the box an card but that only takes a telephone call to them.
t
August 2007