Mulja tv repair portal
Equipment Repairs => LCD TV forum => Topic started by: SlyAKs on November 13, 2012,03:09:21
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Hi guys.. Newbie here, hoping someone with a little expertise can give me info on a transformer/inductor on the PSU of this tv.. The PSU part no. is 667.L27U25-20 and the part in question looks to me like a transformer yet it is labelled L504 on the board (inductor? ). The part itself is also labelled, Xogego LC305. I am actually looking to replace this component and I have trawlled countless web pages for hours now and cant find any info on it... Hope someone here can help.. If I have left any other vital info out give me a shout.. :c017:
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hi
whats the fault with tv
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Cheers for the reply... I have to turn it on and off maybe half a dozen times before it turns on.. The component in question is buzzing/fizzing a lot and when it's warm, the tv fires up first time.. When tv has been left for any length of time, say overnight, if I then take a hairdryer to the component in question, it turns on 1st time.. Any ideas?
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hi
if there are any caps near by change them first
dave
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Changed a few bad caps and all others tested normal with a capacitance meter.. I am nearly convinced it's this transformer, due to the crackling coming from it, especially when cold. Could it be a loose coil or something?.. There is a similar power board on eBay with a tdk transformer in its place and I have done an internet search of the part number and still no joy.. :41:
I resent forking out £50 on a psu when I think it's an easy fix...
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whats the model number of this tv
thanks
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It's C69LC27W18S0002981... Well that's all I can see on it.. Thanks
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http://m910.photobucket.com/albumview/albums/seanl84/20121111_224040.jpg.html?o=0
The part in question... anybody recognise brand? Cannot find it anywhere..
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yes model is LEXOR LC-27W18S
only trouble i had with 1 of these is inverter transformers
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Decided to test the power board again last night when it was cold.. fizzed and crackled as I turned it on and off half a dozen times until it fired up..
Then this morning I took a hairdryer and heated the inductor and it turned on 1st time.. I just don't know what to search for when trying to find a replacement..
There is no info in the service manual about it, only it's circuit I.d/ref (L504)... about to give up on it to be honest..
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If it is designated L504, one can only assume it's an inductor. A transformer in theory would be designated T504. Cant tell much from your picture, it's cropped too much to decide which area of the PS it's in. It may possibly be for mains filtering in which case it should have 4 pins. If so, it could be removed and wire links put in it's place for test purposes. How many pins does it have, anyway?
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There are 5pins on one side and 3 on the other.. On the side with 5 pins only two are soldered to the board.. One reads 230v the other seems to be off the scale of the multimeter or something.. on the side with 3 pins (there are holes on board for 5) only one pin is soldered to the board with the wire coming from copper wrapped around the ferrite exterior.. Don't know if I have explained this well enough... Can't really say much else about it..
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Cant get my thinking gear around that, partstore.com list that power supply as being used in Prima and Polaroid brands as well. Not in stock but available as a special order.
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Right, took a few photos..
http://s910.photobucket.com/albums/ac310/seanl84/
Hope these photos make my last post a little easier to understand...
Cheers, Sean
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Hi Sean,
Any chance of a full P/S piccy as it's hard to make it out with just a couple of square inches ?
All the best - Chris.
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Sorry, thought I had added the photo of the whole ps.. see link below..
http://s910.photobucket.com/albums/ac310/seanl84/
Cheers Sean
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Well, it's on the primary side and it's not the mains filters which are the toroidals on the left. Still cant make any sense of it but then I'm not a designer. Is there continuity between the 3 pins that have the wire wraps on them....have you considered getting the complete board....should be reasonably priced?
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There is only continuity between the 2 on the same side.. the other side is soldered to a copper strip that wraps around the ferrite (under the blue tape).. only reading 1v when turned on..
Decided to put psu into fridge until REALLY cold and it takes a hell of a lot longer to turn on.. checked for dry joints, fuses etc etc.. running out of options.. Definitely psu but anyone I ask tells me its not this coil in question.. I think it is and until I find a replacement I'll never know.. was looking at a psu for this tv and in used condition they are selling for around £50.. I'm fixing this for someone and the don't want to be spending as much as this on parts alone...
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Does anybody at all know what the component is? If you where looking for this component, where would you look and what exactly would you be looking for?
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Indeed we do. Found schematic on net for your p/supply. L504 is merely an inductor. It is used in series with L503, also an inductor,on the dc side of the bridge diode, perhaps because they use only a 100uF main filter - false economy. You could probably bridge out the 2 pins with continuity for test purposes and check if the set starts without tantrums.
No idea where you'd get a replacement (ebay??) but as it is a filter choke only, you may be able to find a coil that does the same job in your box-o-bits.
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Downunder you are legend.. :13: I'll take another look at it today.. only thing I'm thinking about is the pin on the opposite side.. is it needed? Reads 1v or there abouts.. Need to take a look to see where it's going.. Any ideas? :c017:
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L504 is shown only as a coil in the schematic, so I presume third pin goes to primary ground to allow the shielding to act as a radiation stopper, in which case it shoud read zero ohms to the -ve of the main ripple filter C508 - 100uF.
BTW. There is also a current sensing resistor R531 - 0.15 ohms that goes to pin 3 [i.sens] of IC301 via R521.
I presume that reads fine when unit is cold.
I googled the power supply part number to locate the schematic
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Cheers again... Tried bridging the two pins with continuity and it's blown the main fuse on the ps.. And it just so happens, I'm fresh out of fuses.. will be getting more tomorrow.. I just spotted another ps on eBay for £23 so I think I'm gonna grab it before its sold! Cheapest I've spotted anywhere by £20. Still want to get to bottom of this though.. appreciate your input so far Downunder..
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Well that's taken me by surprise. Ah well, at least with another board, you'll be able to experiment.
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New power supply done the job... Cheers for all your help Downunder.. Much appreciated!