LG 32le4900 issue

[jonny78]

Hi again guys! Got this set and the problem is the set turns on fine but there's no picture! Took the back off and no obvious signs of damage.
But when the cable connecting the mainboard to the psu is connected at an angle like this "/" the backlights come on but there is still no picture! All voltages are correct from the power cable to mainboard except the second to last 24v which sparked when I tested it with my multimeter and has left a slight burn mark... I've posted a pic of the voltage chart and the damaged caused by multimeter on 24v point! Will post further pics soon! There is a thread about this TV but the advice was to resolder some points but I've done this and it hasn't helped!

[dick_barton]

Re: LG 32le4900 issue

Check the solder joints of the connector and it's plug and resolder if necessary. Are any of the connector /plug pins burnt where they connect ?

[jonny78]

Re: LG 32le4900 issue

Solder points look fine but I've resoldered anyway but makes no difference! Like I said the one of the 24v pins sparks when I test it with multimeter! I've attached a couple of photos to show you how the backlights come on when cable put in at a particular angle!

[budm]

Re: LG 32le4900 issue

So what Voltages do you have on all those pins of the connector per Voltage chart?
Can we see the pictures of the bottom side of the board where the connector is?
You have three 24V pins, so only one of the the 3 pin sparks?

[dick_barton]

Re: LG 32le4900 issue

I've put a circle around one of the pins which appears to have some staining on?

[R_J]

Re: LG 32le4900 issue

I've put a circle around one of the pins which appears to have some staining on?

I think he made that mark during testing, shorting that +24 volt pin to ground

except the second to last 24v which sparked when I tested it with my multimeter and has left a slight burn mark...

When that plug is at that angle you are removing the error signal from the led driver board
You could also check if you have 12 volts on the t-con board fuse, the fuse seems to be just left of the lvds cable and marked [P]

[jonny78]

Re: LG 32le4900 issue

I think he made that mark during testing

Yes I did! I think it might have been my fault! Here are the voltages

1..NC ERROR = 0
2.. PDIM=12
3...ADIM=12
4...DV_ON=12
5... GND=0
6...GND=0
7... 3.5v=3.5v
8....3.5v=3.5v
9.....GND=0
10. GND=0
11...24V=24V
12...ON/OFF=3V

PIN 11 24 VAULT WAS THE ONE THAT SPARKED AND CAUSED THE MARK (USER ERROR I THINK) but is now reading 24v

Cheers!

[jonny78]

Re: LG 32le4900 issue

I think he made that mark during testing

When that plug is at that angle you are removing the error signal from the led driver board
You could also check if you have 12 volts on the t-con board fuse, the fuse seems to be just left of the lvds cable and marked [P]

OK will check tcon!

[R_J]

Re: LG 32le4900 issue

There are 2 rows of pins (24 total) on that plug that goes to the main board the pins you labeled 2,3 & 4 are just +12 volts, the PDIM, ADIM, DV_ON are on the other row
On 1..NC ERROR = 0, you are checking the NC (no connection) pin not the ERROR pin

[jonny78]

Re: LG 32le4900 issue

There are 2 rows of pins (24 total) on that plug that goes to the main board the pins you labeled 2,3 & 4 are just +12 volts, the PDIM, ADIM, DV_ON are on the other row
On 1..NC ERROR = 0, you are checking the NC (no connection) pin not the ERROR pin

my mistake! ok will check all voltages and report back!