Dead LG42PT353K

mechanic

Active Member
I have recently been given an LG 42PT353K television.
The problem is it is dead.
When plugged into the mains the standby led comes on but then fades out.
There is no response to remote commands either.
Just wondering if there is someone who knows this set?
Can anyone help with any pointers before i open it up?
 
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JayCee

Distinguished Member
The vast majority of this forum's members will never have taken the back off a TV so that'll be the reason no one has replied.
 

Clabs

Active Member
If you are handy with a screwdriver then I would take the back off the TV and check for bulging capacitors on the power supply board. You are looking for bulging on the top silver section.

Here is generic example of bad electrolytic capacitors.

repairing-switching-power-supply-3-jpg.210049
 

mechanic

Active Member
Since my original post ,
i have removed and checked the value of every electrolytic in the PSU.
They are all in spec.
But thanks for the suggestion Clabs.
 

Clabs

Active Member
Ah - that's a shame as that can often be a relatively simple fix.

Have you looked to see if there is a service manual to download? That might give you some pointers.

The only other thing I can offer is that there might be another fault with the power board. Are there any test point voltages on the board to check? Failing that, I suppose it might be worth taking a punt on a used board from ebay - these only seem to sell for £25-30. The problem with that is that it can be a real rabbit hole as you never really know that any used boards you might buy are actually working properly in the first place! I went on a similar journey with a 60" 3D LG plasma but ended up skipping it.

Good luck with it and hats off to you for trying.

Cheers, Mark
 

mechanic

Active Member
Thanks for the reply Mark.
There is no voltage markings.
Thought of a replacement psu but as you say its a gamble.
Tried to find a circuit diagram but no luck.
Looks like a skip job as well, pity.
 

Clabs

Active Member
No worries.

Just another thought - and depending on how determined you are, I just noticed this power supply repair kit on Ebay:


They mention the following components included: R927 / R929 / IC301 / D3** R103 / R104 / R105 / R106 / R107 / R108 + 5 other components. Heatsink Compound.

Probably worth checking the resistors/diode that they do identify. I guess you could always give them a call and see if they recognise your symptoms as a failed power board or if they point to another board.

Cheers, Mark
 

mechanic

Active Member
Thanks for the link Mark.
I have had a look at the PSU and have located most of the components they list.
The fault conditions this kit cures is the one i have.
Some of the components are surface mounted, not my favourite to be honest.
But after some thought i have decided to order the kit.
The reason is i repair this stuff, if reasonably cheap,is that i then donate to the Dementia Charity.
So hopefully i will be successful.
If not its only £20 quid!
 

Clabs

Active Member
Which components are the surface mounted ones? I can't say I am a fan of surface mount when it comes to repair either - I must be getting too old!

If you are based anywhere near Watford, Herts then I have a hot air rework station you are welcome to borrow. It does make life a bit easier.

Anyway - what a great charity - hats off to you :)
 

mechanic

Active Member
The ones i can see surface mounted are resistors.
There is what appears to be a voltage regulator but that is mounted on a heatsink -easy peasy.
What others are i don`t know.
Thanks for the offer of the station.
But i am in Edinburgh!
 
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