Author Topic: adventures repairing LCD power supply  (Read 914 times)

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Offline WacKEDmaN

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adventures repairing LCD power supply
« on: August 10, 2017, 11:39:17 am »
Hey peeps..long time eevblog youtube viewer..first time poster here! Please be gentle! :P
Im not a electronics tech but i do have a limited electronic knowledge with DC stuff.. caps and inductors throw me!  :-//

A few weeks ago my TV decided to release the magic smoke.. before shutting down completely..it was having issues starting up for quite some time.
I took the TV apart an instantly noticed the largest cap had melted/flaking plastic and discoloration on the board where it vented..
I looked around the net at various repair vids and found i should be able to just replace the bad capacitor (nothing else looked damaged..other caps look fine, no swelling or leaking)
I received the replacement cap today and went about installing it. Powered up the TV and still nothing. checked the fuse and it was blown, so i replaced it with the only other one i had, luckly it was the same amperage and also slow-blow. Powered up the TV again...and BANG!..circuit breaker blew, fuse blown, and it took a resistor with it..

Im wondering, if its blowing the fuse and the resistor, there must be another component thats bad right? possably a Fet or rectifier?..
Im struggling to read the resistor color code..both my limited color perception, and the fact that the resistor is damaged, are giving me trouble! can anyone help?!
I dont know where to go next..ive tested the fets in circuit but im not entirely sure they can be tested in circuit..

Ive looked for a replacement power supply board...but it seems theres none in stock anywhere...

Ive attached pics of the board and the resistor..
The cap that blew is the one in the middle at the top...
The resistor is the one to the right of the transformer in the middle..

Any help would be greatly appreciated!
 

Offline sasa

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Re: adventures repairing LCD power supply
« Reply #1 on: August 10, 2017, 01:19:00 pm »
The first image is from here, I suppose:
https://www.amazon.it/GENUINE-POWER-ROADSTAR-LCD-3280KLN-RL05PD04/dp/B00WLSUZAE

I have found several still on sale on ebay...

It is hard to distinguish exact colors from your second image, as well as from first one due flash and shadow.

Always is the best to change all caps if main was blown/melted, as then all suffers hard beating instead. It is unclear now what is damaged, maybe the whole board is unusable.
« Last Edit: August 10, 2017, 01:38:57 pm by sasa »
The 30+ years professional desktop software designer and software engineer
 
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Offline WacKEDmaN

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Re: adventures repairing LCD power supply
« Reply #2 on: August 10, 2017, 02:05:50 pm »
yep that first image is from the amazon link..
i did look on eBay but couldn't find one for sale, at least on eBay Australia..
Im guessing one of the mosfets or rectifiers has failed..but im not knowledgeable enough to diagnose them..

i guess im just gonna have to bite the bullet and buy a new TV   |O  :palm:
 

Offline sasa

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Re: adventures repairing LCD power supply
« Reply #3 on: August 10, 2017, 02:33:39 pm »
Maybe the long shot is to visit or call local TV services and ask for this specific board. Maybe they practice to buy old TVs for spare parts... However, the board probably may not be cheap and with no warranty, then buying new TV with fresh warranty is perhaps the best solution.
The 30+ years professional desktop software designer and software engineer
 

Offline WacKEDmaN

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Re: adventures repairing LCD power supply
« Reply #4 on: August 10, 2017, 02:49:10 pm »
re new tv..exactly what i was thinking..
i may end up keeping this one and eventually get around to getting the board fixed or replaced

thanks for the replies...
 


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