Tv issue

jaybee said:
At this point it depends how good you are at soldering and what equipment you have. If you can replace those components, it could be as cheap as pence, to find them online or from china. As above though, instead you could just get a replacement board and it's simple unplugging and replugging things back in? I think it's well worth it for £85 personally.
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iv got soldering iron kit, iv done fair bit of soldering before mostly tiny smd stuff so everything on this board is huge and easy to do from the looks of it. id like to try a fix before getting a replacement though.
got this going on electronics repair forum too so will keep you guys posted if i make some progress.
back to measuring and testing components on it now.
 

Relay controlled PSU thermistor - Badcaps Forums

Relay controlled PSU thermistor General Electronics Technical Discussion
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if you read above suggests the relay which is above the thermistors has failed (the click/pop you talked about) so the thermistors had been taking all the load of the tv.
if you can test the relay you can maybe prove/disprove that .

maybe ask ebayer seller of complete board to confirm what the thermistors are ? nothing to loose.
 
<possible stupid question>
Is that maybe why it's staying turned on, because the relay is staying energised? (because it's failed open?)
</possible stupid question>
 
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Armageus said:
<possible stupid question>
Is that maybe why it's staying turned on, because the relay is staying energised? (because it's failed open?)
</possible stupid question>
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ahh, you may be onto something there. looks like the relay thingy has a cap on it with clips should be removable.
checked the two relays with multimeter and seems to similar. dont think the relay stays energised because when it power cycles off it makes the click noise again when its powering back on which means relay is turning off then on again.
now would those blown thermistors cause tv to turn on by itself?
 
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odd thing is when the thermistors blew why didnt the fuse blow? would this indicate thermistors blew due to over voltage or over current?
also looking form the back of the board it looks like those 2 thermistors are working in series.
 
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Cyber-Mav said:
odd thing is when the thermistors blew why didnt the fuse blow? would this indicate thermistors blew due to over voltage or over current?
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relay could be unreliable/sooted-up (so thermistor got burned-up taking all the load) .. can you get the relay cover off to look , or put 12v across it to see,
or even listen closely when it's 'live' if board is exposed.

(I have previously cleaned blackened mains relay contacts with wet&dry paper on coffee machine 12v relay - that's 1.3kw though)
 
jpaul said:
relay could be unreliable/sooted-up (so thermistor got burned-up taking all the load) .. can you get the relay cover off to look , or put 12v across it to see,
or even listen closely when it's 'live' if board is exposed.

(I have previously cleaned blackened mains relay contacts with wet&dry paper on coffee machine 12v relay - that's 1.3kw though)
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will do, will probably desolder it from board to check
 
removed the relay and checked inside, it looks perfect. however removing was not a waste of time check the pics:

IMG-20231107-152028.jpg

IMG-20231107-152807.jpg

got the part number of the old thermistor, looks like it is same as the other one on the board - SCK 102

also tested the 2 big bridge rectifiers part number D25XB80 and they both tested fine with multimeter, no shorts.
 
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At this point i guess i can start by replacing those thermistors and take things from there. Need to find. Some equivalent ones from rs components etc. Anyone know which ones to get?
 
jpaul said:
what is the resistance of the others .. can you derive spec.

isn't sck 102 fully documented has 20-25 ohm zero load options https://www.es.co.th/Schemetic/PDF/SCK.PDF

can get them on ebay ? cpc&rs threshold for postage a bit high.
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rs components is close to me so i can drive down and get but they dont have the exact one. do you know if they got an alternative that will work? can buy like 20 of these from ali for 3 quid but will take a month to come. cant be without tv for that long.
 
Cyber-Mav said:
lol
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ok twas a compliment that you may have used dimensions of undamaged thermistors to confirm most likely candidate, in addition to close resistance match,

current of just 2x2A is perhpas smaller that what relay suggests or power consumption of tv.
 
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