LG 47LV5400 no backlights, voltage present

[AcGeorgiegirl]

Hey guys,
I found this exact problem here https://www.badcaps.net/forum/showth...light=47LV5400
but the person posting it stopped the repair with a choice to bake the main in an oven for reflow, etc, and just when you guys were getting to what I think I need to do...I stopped at ( I think? ) Budm's advice to check voltage of the filter caps. I can't remember how that is done.

I have the following voltages at P201:

1 N.C. ERROR
2 12v 11.92 *labeled as should be 12v
3 12v 11.92 "
4 12v 11.92 "
Gnd
Gnd
7 3.5v 3.55
8 3.5v 3.55
9 24v 24.2
10 Pwr.On 3.4v *labeled as should be 24v

A note on pin 10...the blue(top) wire is 3.4v, but the bottom wire is 24v. I don't know how this works, with some psb's, because most I've worked with don't have 2 wires per pin. The actual pin measures 3.4v, but the wire-in area has 2 different measurements.

Also, I did remove the p201 connector to main, which promptly shut power off. I then reconnected p201, which brought power back. I then unplugged tv from power and disconnected p201. Replugged power, but no juice.

[dskall]

Re: LG 47LV5400 no backlights, voltage present

So can you explain your problem. No backlights? The legend for your connector is like looking at it from wire end. Top row is probably odd numbers. You check main caps across pos and neg of cap in dcv

[AcGeorgiegirl]

Re: LG 47LV5400 no backlights, voltage present

Yes, no backlight. Powers on fine.
When you guys say, "across both pins" of the caps, do I just put neg to neg and pos to pos(probes to pins?). Is this while the tv has power plugged in and power switched on?

[dskall]

Re: LG 47LV5400 no backlights, voltage present

yes. What is voltage at drv_on pin? You have image on screen with flashlight?

[AcGeorgiegirl]

Re: LG 47LV5400 no backlights, voltage present

Sorry, I forgot to include the labels. Pin # 4 is the Drv_On, and it's 11.9v.

Yes, I've tried the flashlight test with nothing showing.

[budm]

Re: LG 47LV5400 no backlights, voltage present

https://www.badcaps.net/forum/attach...8&d=1497457531
P201 looking at the top side of the board you can see the expose pins, those are ODD number pins.
Pin 1 is PWR-ON
Pin 3 is 24v
Pin 5 is GND
Pin 7 is GND
Pin 9 is 3.5V
Pin 11 is 3.5V
Pin 13 ....
Pin 15 ......

To get to the EVEN pins you have to get to the bottom side of the board or the wire entrance side of the connector, that said, DRV-ON pin is Pin 18.
You read the wrong pin (you were reading the 12V pin) that is why you report the reading of 12V.

[dskall]

Re: LG 47LV5400 no backlights, voltage present

Don't think your pins are correct.

[AcGeorgiegirl]

Re: LG 47LV5400 no backlights, voltage present

Ok, I understand how that works now. The pin 18 has no voltage.

[AcGeorgiegirl]

Re: LG 47LV5400 no backlights, voltage present

No voltage for DRV_On, and the filter caps read at most 398(fluctuates from 390 to 398).

[tvtimmy]

Re: LG 47LV5400 no backlights, voltage present

Read this thread LG 55LV9500 LED TV Black Screen

[geeforce]

Re: LG 47LV5400 no backlights, voltage present

Read this thread LG 55LV9500 LED TV Black Screen

How long do your fixes last? Not sure how comfortable I feel selling it after just blowing hot air on the processor for a minute lol

Any rate of return on these?

[neilc6]

Re: LG 47LV5400 no backlights, voltage present

Ive baked a PS3 board and a laptop logic board and both had the problems come back after weeks. Proper repair is to have the BGA reballed.

https://ebay.us/LkWohl