LG hi-fi system (lol i know ) LCD backlight LED,s not working

[mad1]

Hello and hi all ,looking for a bit of advice/knowledge on a led circuit ,have removed the led pcb board from this old machine ,its a standalone circuit board the protudes through the big board and lights the rear of the lcd with 3 leds in series with a diode on it ,its marked 12v .

i first checked for power and there is a 12v supply and return to the board ,what i dont know is if there is a separate driver elsewhere or if this circuit is supposed to be 12v ....if that makes sense .

de-soldered the leds and they have checked ok on a 3v battery supply .The first sign of trouble was the lcd backlight display flickering ,it flickered continuously on and off for a while and eventually went down ,was not aware it was just the back lights until i disassembled and seen the lcd was functioning ,i was just a case of not being able to see it .

Could anyone point me in the correct direction ,should this pcb with three in series leds be fed with 12v ?

as mentioned it has one other diode in parallel across the circuit ,what is the purpose of this diode is it hi/low voltage protection ...ect ect .It checks on a multi meter as having one directional properties

Was considering buying a 5cm strip of leds and just using that but would prefer to repair it if poss ,the lcd has two lots of backlights ,3 leds in each ,both are not working .


Any help would be appreciated ,cheers for reading .

mad1

 

[poor mystic]

Hi
The problem you have cannot be solved in general terms; you need the circuit diagram for the particular model of equipment which is faulty.
I have no such diagram, and don't even know the model of your hi-fi.
Even knowing the model might not help, because the circuit diagram might not be available as a free download. It might be very difficult to find such a diagram.

I can offer general advice as follows:
Almost all electrical/electronic faults are connection faults. That said, active devices do fail, and no obvious connection is involved. Poorly soldered joints might cause such faults.

You could post a photograph of both sides of the circuit board you're inquiring about, and we might be able to see how to answer some questions.

Mark

 

[mad1]

Hi poor mystic ,cheers for taking the time to reply .

Am just going for the 5cm strip of leds ,will pick up a 12v feed and job will be a good un .

i think it will be for the best