Originally posted by: ylexus
"I am trying to argue with a retailer that I was unlucky to buy a defective TV set from the beginning (a manufacturer's defect that caused 1 bit of address line to fall off after 4 years of use, for example)."
"You will have to explain this in better terms. "
I think my first paragraph above explains it. If I prove that it's an exceptional event for such a TV to fail within 4 years, this will most likely be considered by a court (if it ever goes to court!) to be a proof of the fact that my TV was initially defective which then according to Sales of Goods Act 1979 forces the retailer to replace/repair it.
The retailer will pass this back to Sony. Sony will state that the MTBF of the design is fit for purpose, but any MTBF will have a distribution curve and your failure is just a point on this curve. Unless you can prove that a high percentage of this model of TV show this failure then I can't see that you have a case.
I disagree slightly with the previous poster, it is not "wear", but it would not be unexpected for a fault to randomly occur after that period of time. I get the impression you are hoping for a "professional statement" here to support your case: I regret to say that no reliability engineer is going to state that any semiconductor component will last for a specific length of time. The fact is that they are subject to random failures, and there's nothing the manufacturer can do about that. You could even generalise and say that more modern equipment will have a tendency to fail in a shorter space of time to 40 year old equipment because it has more (vastly more!) transistor junctions in. It's not quite linear, because manufacturing methods have improved, but 4y8m sounds pretty good going to me for a piece of modern domestic equipment.
But if you are really bothered, I would recommend that you find Sony discussion forums to see if there is a history of failures with this model, then maybe you will have grounds for a group action.
On another issue, that's why I prefer FM radios to DAB: less bits in to go wrong!! (And they draw less power, and turn on straight away...)
Andy Millar CEng MIET CMgr MCMIhttp://www.linkedin.com/in/millarandy
"The aim of argument, or of discussion, should not be victory, but progress." Joseph Joubert