LG 60PN5700 Powers on, No Video No Picture

[saintlouis74]

I just acquired a LG 60PN5700 from a friend who didnt know what was wrong with it. The TV powers up and I see a small flash on screen but then it cycles back off then on. It seems to be on but no video or sound. I traced the 5v and 17v around the boards it seems to be getting around to every board.. I tried to use a heat gun on the main board and rework it, didnt have any effect. What should i focus my attention on?

PB P/N: EAX64880001
MAIN P/N: EAX64870004


### P813 ###
M_ON = .61v
PL_ON = 1.22v
5.2V = 5.2v
G
G
5.2V = 5.2v
5.2V = 5.2v
G
17.V = 17.1v
Auto_G = 4.1v
AC_ON = 5.0v
17V_DET = 2.357v
VS_ON = .64v
G
VS_DET = 2.7v
5.2V = 5.2v
G
17V = 17.1v


### J148 ###

VS = 203v
VS = 203v
-
GND
GND
VA = 55v
5V = 5.2v

[R_J]

Re: LG 60PN5700 Powers on, No Video No Picture

If you look at the control board you will see two test points labeled EXT_AUTO_GEN, unplug the tv, disconnect the plug going between the main board and the control board, short the two test points on the control board and plug the tv in, You should get test patterns on the screen, If you do, the fault is likely on the main board

[saintlouis74]

Re: LG 60PN5700 Powers on, No Video No Picture

If you look at the control board you will see two test points labeled EXT_AUTO_GEN, unplug the tv, disconnect the plug going between the main board and the control board, short the two test points on the control board and plug the tv in, You should get test patterns on the screen, If you do, the fault is likely on the main board

Thank you, the self test worked, and some smoke came of a chip on the main board, so its pretty obvisouly the main board it damaged. thank you again for your time

[R_J]

Re: LG 60PN5700 Powers on, No Video No Picture

Doing this test would not have caused a problem with the main board. Which chip on the main board smoked? maybe the board can be repaired.

[saintlouis74]

Re: LG 60PN5700 Powers on, No Video No Picture

Doing this test would not have caused a problem with the main board. Which chip on the main board smoked? maybe the board can be repaired.

this is not the my actual board but a identical one. this is the chip that was burnt on the top and was smoking

[R_J]

Re: LG 60PN5700 Powers on, No Video No Picture

That would be the audio output ic. (STA380BWF), If it is killing one of the voltages you might be able to disable it and see if the rest of the tv works. If the 3.3 volts is being killed, trace that pin and there should be a small smd coilyou could remove to disable the ic, same goes for the P_17v

[saintlouis74]

Re: LG 60PN5700 Powers on, No Video No Picture

That would be the audio output ic. (STA380BWF), If it is killing one of the voltages you might be able to disable it and see if the rest of the tv works. If the 3.3 volts is being killed, trace that pin and there should be a small smd coilyou could remove to disable the ic, same goes for the P_17v

Im sorry, after taking the TV back out of storage and getting the board out, i realized i circled the wrong IC..

[R_J]

Re: LG 60PN5700 Powers on, No Video No Picture

That looks like the hdmi ic, I can't make out the number, look up the number, find the pdf and locate the vcc pin so you can disable the ic in case it is shorting one of the voltages, again the board should work with the ic disabled, just no hdmi.

[saintlouis74]

Re: LG 60PN5700 Powers on, No Video No Picture

That looks like the hdmi ic, I can't make out the number, look up the number, find the pdf and locate the vcc pin so you can disable the ic in case it is shorting one of the voltages, again the board should work with the ic disabled, just no hdmi.

Ok will do thanks again.

IC3303 is the chip location.

i cant make out any numbers on the ic because its burnt

Sil1292CNUC

[saintlouis74]

Re: LG 60PN5700 Powers on, No Video No Picture

That looks like the hdmi ic, I can't make out the number, look up the number, find the pdf and locate the vcc pin so you can disable the ic in case it is shorting one of the voltages, again the board should work with the ic disabled, just no hdmi.

Which one would be the vcc pin?

[R_J]

Re: LG 60PN5700 Powers on, No Video No Picture

In this case it's VDD5, pin10 5v

[saintlouis74]

Re: LG 60PN5700 Powers on, No Video No Picture

ok... It still comes on, and i notice after the 2nd relay click it lights up for a sec then goes dim

[R_J]

Re: LG 60PN5700 Powers on, No Video No Picture

There are other voltages on that ic, see if they are there or are being loaded down, +3.3v & +1.2v, if the ic is badly shorted it could be killing the clock or data lines also
On plasma's you will get that first precharge flash, if the hdmi chip is burnt there may be other damage on the board.

[Pionex2020]

Re: LG 60PN5700 Powers on, No Video No Picture

Ok will do thanks again.

IC3303 is the chip location.

i cant make out any numbers on the ic because its burnt

Sil1292CNUC

Does anyone know where this ic ( SIL1292CNUC ) may be purchased.

[charlesjudd]

Re: LG 60PN5700 Powers on, No Video No Picture

Hi, Do you have a schematic for the SMPS power board (EAX64880001) ?
During servicing the one I'm trouble shooting, I remove a couple of what appear to be tiny diodes on the back of the board near IC801.

The diodes are marked:
33
BE

15
BG

(no way to read them unless under a microscope).

Now I have them pulled off and realise they are different components with different values, I have idea which one goes in which spot, or which way around the diodes should be. A schematic would help out with this.

Any chance you can help with either measurements from your board (OHMS value for each, and Diode test so I can identify the values and placement direction?)

I've marked the read board view attached image with red box and blue box indication their location on the board.

Rookie error

[charlesjudd]

Re: LG 60PN5700 Powers on, No Video No Picture

Hi, Do you have a schematic for the SMPS power board (EAX64880001) ?
During servicing the one I'm trouble shooting, I remove a couple of what appear to be tiny diodes on the back of the board near IC801.

The diodes are marked:
33
BE

15
BG

(no way to read them unless under a microscope).

Now I have them pulled off and realise they are different components with different values, I have idea which one goes in which spot, or which way around the diodes should be. A schematic would help out with this.

Any chance you can help with either measurements from your board (OHMS value for each, and Diode test so I can identify the values and placement direction?)

I've marked the read board view attached image with red box and blue box indication their location on the board.

Rookie error

Should read "I have NO idea which one goes in which spot, or which way around the diodes should be. A schematic would help out with this."

[R_J]

Re: LG 60PN5700 Powers on, No Video No Picture

What is the number on IC801? that might help, I don't think there is a schematic for this board. The two diodes are zener diodes, one is 15v one is 33v, The anode end of each diode likely connects to hot ground.
If it is a L6599a?
I suspect one (ZD804) connects to pin 12 vcc line.
I would think ZD805 (blue) would be the 33v zener and ZD804(red) would be the 12v zener.