Loss of Picture

[Gardian]

We have a perfectly conventional setup to receive UK tv & radio here in France: SKYbox, LCD tv, DVD player.  It has all worked fine for nearly 5 yrs, the only change being the new tv a couple of yrs ago.

Two days ago, the tv gave sound, but no vision when switched on. Did a bit of button pushing, but to no avail.  Re-connected using an old portable tv and no problems, so obviously not the scart or aerial leads. Then tried the classic problem-solving technique: switch off, unplug at the mains, leave for a couple of minutes and fire up again.

Sorted !  My question is "Why does it happen?"  Our son said that he experienced the same problem a week or so ago and fixed it as above, so not an isolated occurrence.  Strange - any ideas anyone?   

[Théière]

It could be the switch mode power supply that provides the high power required for the tube, that's the part that usually begins to whistle or produce a pitched tone as they get older (before they fail). Or simply the connector on the back of the tube, or any other connection near something warm. As the tube heats up and cools down it causes the connector to work loose and somtimes cause a slight disconection. Switching it off allows it to cool and the metal contract and make contact once again.

[RicandJo]

On a modern LCD TV it's more than likely just a stuck relay, turning off then on again sends a new power signal to the relay, usually enough to click it over and get it working normally again.  Either that or a start up logic sequence fails, turning off and on starts the whole sequence off again.

Believe it or not it's a usual fix for aircraft avionic boxes - power off and on again, then run a bite test.  Nine times out of ten there's no fault.

 

[Théière]

Oops, sorry missed LCD telly, just what RicandJo said [:$]

[Gardian]

Many thanks all.  At least it doesn't look like a new tv, which I had begun to fear!