Well, I'll try to answer your question with this link (which suggests likely sources):
http://www.sharp.co.u...s-and-accessories.htm
However I feel compelled to ask the question "WHY?"
I bought a really good quality colour portable TV (Sony Trinitron) for a fiver at auction last year. Earlier this year a friend gave me another good portable TV for free, simply because he had no use for it. A charity shop in Stowmarket currently has one for sale for £2.50. The British Heart Foundation has 'Furniture & Electrical' shops, all over the country, which will sell you a good quality colour portable (with a warranty) TV for £5 or £10. It's almost certainly going to cost you more to buy the switch than it is to replace the telly. So I have to repeat my question: WHY?
Chris