Thanks for the info faflefevre, every little helps. I had the impression it was going protect mode. I was hoping on some 'knack' on by-passing it, the whole thing 'appears' trip just before the back light has fired, guessing as jordan the previous poster said.
I must try and get the service info.... if only they were all like the old fashioned Grundigs when they tucked a circuit diagram on the inside - going back a bit, can't have it too easy though!
Dave