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Thread ID: 41022	2003-12-27 07:07:00	O.T. Technical	B.M. (505)	Press F1

Post ID	Timestamp	Content	User
203488	2003-12-27 07:07:00	OK here’s the problem. A mate’s little 14” Philips TV stopped dead. No picture, No Sound, No Raster. The nice man at the TV shop advised him it wasn’t worth fixing and promptly sold him a new one. As you’ve probably guessed it has wound up at my place, could be good for spares you know. :D And, as you’ve probably also guessed curiosity quickly got the better of me. ;) Investigative surgery reveals what I suspect is a would be resistor which is now open circuit. Written upon this white cube is the following: Philips RMW L 2R2 5% 5W 834. Question is what was the value of this resistor? I gather it was made by Philips, is rated at 5 Watts, and has a tolerance of 5% but what does RMW L 2R2 834 stand for? I think they’re just trying to make things hard for us old fellows! Compliments of the season to all. Bob	B.M. (505)
203489	2003-12-27 07:15:00	Well, it's a 2.2 ohm Radial Mounted Wirewound resistor, but I dont know what the L stands for. Cheers	Terry Porritt (14)
203490	2003-12-27 07:32:00	Thanks Terry, It's 2meg + now, so as It's in the power supply I might just be onto it? Cheers Bob	B.M. (505)
203491	2003-12-27 07:33:00	It may be that a serious short circuit popped that resistor Bob, so before investing any money in spare parts, if you have the means to do so I recommend that you check for any short-circuit or very low resistance to ground from both sides of that resistor. If using a meter, reverse the probes on each test as some faulty solid-state components may show a short one way only. If you don't have a meter, take an ordinary 75 watt light bulb and connect it in place of the open resistor. If it lights up brightly when you turn on the power to the set then there is probably a major electronic breakdown present. If however it lights up at low to medium brilliance and sound (and'or a dim picture) are present then there is a good chance that replacing the resistor will see the TV burst into life again. This scenario is only valid of course if the supply fuses are still intact. If they have blown the chances of it being a simple resistor failure are somewhat less. :( Cheers Billy *<8-{)	Billy T (70)
203492	2003-12-27 08:09:00	Good point Billy . Yes, I’ve my faithful old Avo 8 and a Dicky Smith Digital . Never too sure which one to use as I’m told the Avo can damage some circuits when measuring resistance . Trouble is, some semi conductor’s won’t even turn on using the digital . Anyway, all that aside, the fuse is 100%, and there is no short to earth, which is a bit encouraging . Oddly, this is the first TV or Monitor I’ve ever operated on that shows absolutely no sign of anything having even been warm . Tomorrow I’ll see if Dick Smith can supply a 2 . 2 ohm resistor and take it from there . Thanks again Bob	B.M. (505)
203493	2003-12-28 01:14:00	And, of course, it was made in the 34th week in year "8" (98, 88?). (The week count starts with the first week in the year which has a Thursday in it. :D) How much more difficult do you want the codes to be? The 2R2 is a very good convention: decimal points disappear in photocopying, and wear off components, so the multiplier is used instead -- R=1, K=10^3, M=10^6. Similarly with capacitors when marked in nano- and micro-farads ... evcen occasionally pico- (though I don't really believe in fractional picofarad capacitors. ;-)).	Graham L (2)
203494	2003-12-28 21:19:00	I'd still do the lightbulb trick before powering up with a new resistor Bob, but all the indications are that it was a simple resistor failure, possibly damaged over time by current surges at switch on. Re multimeter damage to semiconductors, I have never personally seen any semiconductor damaged by application of a multimeter, though I concede that it could happen with particularly sensitive devices with low forward voltage thresholds and very low current handling capability, or Mos type semiconductors that can't handle reverse voltages greater than a volt or so. That risk does not exist in the power & scan circuits of a TV so I'd make resistance tests and see what you get. Digital meters are useless for resistance measurement on semiconductors unless they have a semiconductor test facility built in. When my trusty old Hioki AS100D finally died I bought a cheap & simple analogue meter from DSE (cat Q-1025) and it does the job just fine. Cheers Billy *<8-{)	Billy T (70)
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