LG 39LN5400 no power

[nomoresonys]

Re: LG 39LN5400 no power

I wouldn't mess with the bga chip unless you have prior success with them and the proper equipment, best would be to get the right replacement board.

[nomoresonys]

Re: LG 39LN5400 no power

.

[unimatrix93]

Re: LG 39LN5400 no power

I wouldn't mess with the bga chip unless you have prior success with them and the proper equipment, best would be to get the right replacement board.

Well yes, but the problem is I cannot find any proper replacement board for this TV, at least for a reasonable price.

I think i will try to transfer the lvsd connector and the other components then. Its for the same tv, but for a 32inch, instead of the 39.

[nomoresonys]

Re: LG 39LN5400 no power

None on ebay? : There are individual eBay sites for Belgium, Denmark, Finland, France, Germany, Greece, Hungary, Ireland, Italy, the Netherlands, Norway, Poland, Portugal, Russia, Spain, Sweden, Switzerland, Turkey, and the UK.

[unimatrix93]

Re: LG 39LN5400 no power

I succesfully transfered the connector and the other components to the new mainboard.
The TV is now turning on, backlight works but I have a black screen.

I measured 12v, vgh 30 and lgv -8V on the TCON and when I disconnect the left/right side of the LCD they turn white according to the disconnected sides.

What could be the problem?

[dskall]

Re: LG 39LN5400 no power

You could now have a software problem. Did you check closely for shorted/open connections? You might try probing the double lines on lvds for data going out of main. should get ~ 1.2v

[unimatrix93]

Re: LG 39LN5400 no power

You could now have a software problem. Did you check closely for shorted/open connections? You might try probing the double lines on lvds for data going out of main. should get ~ 1.2v

I'm checking it right now, just have to turn over the TV.

This is how the left side of the LCD looks like when I turn on the TV:

https://1drv.ms/v/s!Ar4hHP2toEdog6Bs...F8eJw?e=3i1VFa

[unimatrix93]

Re: LG 39LN5400 no power

You could now have a software problem. Did you check closely for shorted/open connections? You might try probing the double lines on lvds for data going out of main. should get ~ 1.2v

Here are the values measured on the components top pins from left to right:

3.32V
3.36V
0.5V

1.02V
0.5V
1.06V

1.21V
0.5V
1.07V

1.92V
0.5V
1.02V

1.06V
0.5V
1.20V

1.06V
0.5V
1.20V

0V
3.6V
0V

[dskall]

Re: LG 39LN5400 no power

Its for the same tv, but for a 32inch, instead of the 39.

Looks like you have data coming out. Two different size screens is probably the problem.

[unimatrix93]

Re: LG 39LN5400 no power

Looks like you have data coming out. Two different size screens is probably the problem.

What should I try then? Besides ordering another mainboard?

Which component determines what signals coming from the mainboard?

I have a IC programmer, I could try reprogram the SPI chip If it would help.

[dskall]

Re: LG 39LN5400 no power

Not a firmware guy. I would say ic102. I think LOTAS is into the firmware part. I would message him.

[nomoresonys]

Re: LG 39LN5400 no power

do the alphanumeric digits on the white sticker of both mainboards match, I think 32 thru 47 should be ok if they match.

[nomoresonys]

Re: LG 39LN5400 no power

ok, I forgot you had a different mainboard, I'd say that's the problem, mismatch there, also bad leds right?

[unimatrix93]

Re: LG 39LN5400 no power

ok, I forgot you had a different mainboard, I'd say that's the problem, mismatch there, also bad leds right?

I fixed the backlight, which did not help. After that I narrowed it down to the main board as other guys suggested. The SOC is burned on the original mb so i ordered a new one which turned out to be for the same series of LGs just a smaller one.

I transferred the LSVD connector, so I transferred the lvsd connector and some caps and resistors to match the og board. Everything else is 100% same on the new mobo. ICs, markings, everything. I even checked if the vias are leading to the same points with a DMM and my microscope...

After that the TV turned on successfully but with black screen. Backlight works too. I couldn't find a short on the TCON/Riser either... I was thinking about transferring only the SOC but I never done BGA before and I'm afraid a screw it up

[lotas]

Re: LG 39LN5400 no power

Compare these places and rearrange the resistors, as it was on the native board.

[lotas]

Re: LG 39LN5400 no power

But first, you should find out if your T-con is working (check the voltage at the test points), and there are no short circuits on the matrix bars, some T-cons can be driven into test mode.

[unimatrix93]

Re: LG 39LN5400 no power

Compare these places and rearrange the resistors, as it was on the native board.

But first, you should find out if your T-con is working (check the voltage at the test points), and there are no short circuits on the matrix bars, some T-cons can be driven into test mode.

I found a few differences:

IC1903
OG: HD38D
NEW: HS40C
Should I replace them?


Also there is no resistor on R176 on the OG board.
R226 is on R227 on the OG.

The Tcon panel and the matrix should be okay, voltages were there and the I couldn't find any short either.

[lotas]

Re: LG 39LN5400 no power

I don’t know about IC1903, I need to compare datasheets, what’s the difference. Look at the resistors where it should be, solder it where it should not be, then remove them.

[lotas]

Re: LG 39LN5400 no power

T-CON has its own dc-dc converters for powering the matrix and they must match their rating.

[unimatrix93]

Re: LG 39LN5400 no power

I don't know about IC1903, I need to compare datasheets, what's the difference. Look at the resistors where it should be, solder it where it should not be, then remove them.

I replaced the resistors, still no luck.

I will transfer EEPROM and the SPI now.