Lg 42ld450

[sordids999]

Hi
This tv picture is fine but it seems to have like wavy lines going horizontal on the screen and the main board seems to be making a squealing sound,the guy I bought it off said the picture would play up so he had the knock the back of the TV where the main board is positioned

Any ideas ?

[sordids999]

Re: Lg 42ld450

Opps forgot the picture

[tom66]

Re: Lg 42ld450

Try changing input source frequency - one easy way is changing the output of a PS2 or PS3 (over composite video cable, yellow white red) from PAL to NTSC (50Hz/60Hz), or by using a computer and changing the frequency. When you do this, do the lines behave differently?

[sordids999]

Re: Lg 42ld450

http://www.youtube.com/watch?v=isQV2UoS6qc
tried changing on my pc tom but no difference ive added a short video showing the waves and the noise

[tom66]

Re: Lg 42ld450

What voltage do you measure across the 450V capacitors on the power board?

[sordids999]

Re: Lg 42ld450

386 volts

[tom66]

Re: Lg 42ld450

Video private?

[sordids999]

Re: Lg 42ld450

Opps public now not sure what happened

[tom66]

Re: Lg 42ld450

Can't see anything wrong with that image myself. The lines do not change with 50 or 60Hz?

[sordids999]

Re: Lg 42ld450

no tom tried 50 and 60 hz the tv has horizontal lines going up and down the video did not really show this but the noise is another thing its coming from the main board

[tom66]

Re: Lg 42ld450

Can you locate where on the main board the noise is coming from?

[sordids999]

Re: Lg 42ld450

hmmm thats going to be hard but ive also noticed to the right of the screen next the the plastic housing blue dotted lines going all the way down and red dotted line going all the way down on the left would have been hard to spot

[tom66]

Re: Lg 42ld450

Try using a toilet-roll tube to locate the source.

[sordids999]

Re: Lg 42ld450

clearer picture

[sordids999]

Re: Lg 42ld450

@tom i just put a toilet roll holder over on this part and it stopped the noise

[tom66]

Re: Lg 42ld450

That looks like a DC-DC converter section. Check the output voltages from the power supply, are they within range?

[sordids999]

Re: Lg 42ld450

Pin 1 nc pin 1 error
pin 2 12v (12.19) pin 2 p.dim (2.48)
pin 3 12v (12.19) pin 3 a.dim (1.70)
pin 4 12v (12.19) pin 4 inv on/off (2.80)
pin 5 gnd pin 5 gnd
pin 6 gnd pin 6 gnd
pin 7 3.5v (3.37) pin 7 3.5v (3.37)
pin 8 3.5v (3.37) pin 8 3.5v (3.37)
pin 9 gnd pin 9 gnd
pin 10 gnd pin 10 gnd
pin 11 20v (20.1) pin 11 20v (20.1)
pin 12 power on (3.0) pin 12 20v (20.1)

[sordids999]

Re: Lg 42ld450

tom if i touch this with my meter leads the noise goes but comes back after 30 seconds

[tom66]

Re: Lg 42ld450

Confirm full model number of your TV, including the suffix e.g. -XA. It might be written elsewhere on the label. Need to get service manual for this set and check main board voltages.

[sordids999]

Re: Lg 42ld450

Model 42LD450-ZA
Product code 42LD450-ZA.AEKWLJG