LG 50PM670S no image

[dick_barton]

Re: LG 50PM670S no image

You could try Ohms Supplies and see if they can offer a substitute.
http://www.ohmsupplies.co.uk

[tietoharrastelija]

Re: LG 50PM670S no image

Ah, loose ribbon.

What is correct -VY (I got positive Voltage on multimeter) and +VSC?

I know that VA is 55v and VS 205V

[tietoharrastelija]

Re: LG 50PM670S no image

Measured voltages DMM:

-VY = 190v

VSC = 143v

VS = 204v

VA = 54V

VZB = 150V

Are these right? When I plug HDMI cable from computer to TV I heard sound but no picture I touched white square resistor on Y sus board, it was bit warm..

[dick_barton]

Re: LG 50PM670S no image

Disconnect the ribbon cable from the mainboard to the logic board and connect the pins on the logic board as in post #4. Then power on.

[tietoharrastelija]

Re: LG 50PM670S no image

Disconnect the ribbon cable from the mainboard to the logic board and connect the pins on the logic board as in post #4. Then power on.

Tested that but still no picture.. (used small wire and removed LVDS cable)

[dick_barton]

Re: LG 50PM670S no image

Have you carried out the test since you did the last repair in post #17

What is the blink rate of the led on the logic board?

[tietoharrastelija]

Re: LG 50PM670S no image

Have you carried out the test since you did the last repair in post #17

What is the blink rate of the led on the logic board?

https://photos.google.com/share/AF1Q...pQMW81YURORUdR

Link to video where green led blinking. (End of video led blinking better, sorry for background noise)

[dick_barton]

Re: LG 50PM670S no image

The blinking rate I believe should be an equal on/off period which the video shows that it is not.
It looks as though it is blinking 1 long and 2 short blinks and then repeating.

Unfortunately although I know that the blink rate is wrong I don't know what it points towards. Perhaps someone else could offer advice.

Have you tested the Ybuffers?

[tietoharrastelija]

Re: LG 50PM670S no image

The blinking rate I believe should be an equal on/off period which the video shows that it is not.
It looks as though it is blinking 1 long and 2 short blinks and then repeating.

Unfortunately although I know that the blink rate is wrong I don't know what it points towards. Perhaps someone else could offer advice.

Have you tested the Ybuffers?

Tested Y buffers for shorts yesterday. Now VA is stable 55v and VS 205v (adjusted trim).

But -VY and VSC voltage now changes strange and show unrealistic voltages, under 100v and over 200v (I have cheap multimeter). Maybe something causes ripple? Some capacitor?

[tietoharrastelija]

Re: LG 50PM670S no image

Now -vy output about 70v (trimmer not changing) something wierd.. Tested without panel flex cables also (but then Voltage was 0v)

[tietoharrastelija]

Re: LG 50PM670S no image

Tested almost all caps on y sus board:

C204: 25V 330uf 0.35 ohm 346 uf
C201: 25V 330uf 0.37 ohm 343 uf
C102 25V 330uf 0.35 ohm 345 uf
C251: 250V 47uf 0.49 ohm 49 uf
C264: 250V 47uf 0.44 ohm 49 uf
C257: 200V 47uf 0.58 ohm 46.58 uf
C303: 250V 10uf 1.6 ohm 9 uf
C263: 250V 10uf 2.1 ohm 10 uf
C151: 50v 100uf 0.20 ohm 94.07 uf
C213: 50v 100uf 0.19 ohm 91.03 uf
C209: 50v 22uf 4.5 ohm 21.66uf
C101: 50v 100uf (once replaced) 0.28 ohm 102.4uf
C256: 50v 22uf 6.3 ohm 20.75uf (here's something when ohms increases over time while being in the meter?)
C134: 250v 220uf (not tested)
C137: 250v 220uf (not tested)
C137: 250v 220uf (not tested)
C216: 50v 100uf 0.02 ohm 105.3 uf
C210: 50v 100uf (once replaced) 0.32 ohm 102.9uf
C214: 50v 100uf (once replaced) 0.27 ohm 102.7uf
C305: 25v 47uf (once replaced)

What caps needed / is good to replace?

[dick_barton]

Re: LG 50PM670S no image

Here's a guide from an ESR meter table.

[tietoharrastelija]

Re: LG 50PM670S no image

Maybe EAX64300301 burned, looks like one of it ic has bright spot on top when power is on tv..

[dick_barton]

Re: LG 50PM670S no image

Maybe EAX64300301 burned, looks like one of it ic has bright spot on top when power is on tv..

Do you have a picture of it?

[Hamie]

Re: LG 50PM670S no image

Dont think it's the caps. Itll likely be a cold or cracked joint. Check the pins on those transformers.