matsui DTR 1 digital reciver?

It freezes some times then pixelates then switches its self off
I have soldered the joints in the arial lead
pushed scarts in and out 5 times attempting to clean them
Set for new instalaton unpluged airia lead then run (of cause it found nothing) unpluged power for 5 minutes repluged arial & power then run new instlation it worked for 8 or 9 hours and stared the same problem can any one surgest any thing else please