logik 808 dvd recorder loosing signal?

How can I fix my dvd recorder. Been ok but now keeps loosing signal, have checked all wires and scarts , seem to be ok. Tv working fine so not the ariel but when dvd plugged in tv goes off as well. On dvd chanel comes on showing full signal strenghth and then after few seconds signal strenghth decreases and looses chanel My recorder is a logik LDVR808 DVD RECORDER any sugestions much appreiciated thanks