Riddled TV Repair Forum

zara.engineer1 · Joined: 10 Feb 2016 Posts: 1 Location: lebanon

Hello

I have a problem with screen LED (LG) Model : E1940S

This LED works on 12V but the user have supplied it with 19.5V.
And now there's no signal or any thing on the screen when it's turned on.

The service manual :

http://elektrotanya.com/lg_e1940s-pnt.pdf/download.html

In page 28 there's a 12 to 5 converter but there's no output on zener ZD701.

So I deduced that the smps IC is U705 (MP1584EN) is stop working.

I decided to put external power supply 5V on ZD701 .

the regulator U701 gives 3.5V but I didn't find the other regulator 1.8V U703 because it's not on my board!

so what are your suggestions to help me.

thank you in advance.

I have a good experience in electronics but I'm beginner in repairing.

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