Sharp LC-40LE810UN Zero Power

[xoicorez]

After reading the existing threads on here, I'm still not sure where the problem is exactly. There is no backlight and no standby light when it is plugged in. I don't have much experience working with electronics on this level.

Based on the previous threads (1 , 2) , I've measured these items on the board:

[budm]

Re: Sharp LC-40LE810UN Zero Power

So right now with just power supply board connected to AC. Do you get any DCV on the power supply connector pins that goes to the main board?
The connector has name for each pin so make sure to put down the pin name and follow by the Voltage reading for each pin.

[xoicorez]

Re: Sharp LC-40LE810UN Zero Power

I'm not sure which connector that is? Is it PD?

[nomoresonys]

Re: Sharp LC-40LE810UN Zero Power

Yes PD.

[xoicorez]

Re: Sharp LC-40LE810UN Zero Power

Pin 1 - 1 going down to 0
Pin 2 to 10 - 0
Pin 11 - 4.9
Pin 12 0.1

[dick_barton]

Re: Sharp LC-40LE810UN Zero Power

Are you certain that measurement D was 19 ohms and not 19 Kohms?

[budm]

Re: Sharp LC-40LE810UN Zero Power

Pin 1 - 1 going down to 0
Pin 2 to 10 - 0
Pin 11 - 4.9
Pin 12 0.1

To get 16V (C) for the running Voltage for the SMPS circuit, it means that standby power supply is running, that is why you do have standby 5V on pin 11, no need to check anything in that hot side of that power supply section.

As I indicate, PD connector has pin name so you need to put down pin name follow by the Voltage reading so we can easily see what it has does not have for each pin. Also PD connector has 24 pins, so you need to report them all, the exposed pins you can see from the top side of the board are ODD number pins.

[xoicorez]

Re: Sharp LC-40LE810UN Zero Power

To get 16V (C) for the running Voltage for the SMPS circuit, it means that standby power supply is running, that is why you do have standby 5V on pin 11, no need to check anything in that hot side of that power supply section.

As I indicate, PD connector has pin name so you need to put down pin name follow by the Voltage reading so we can easily see what it has does not have for each pin. Also PD connector has 24 pins, so you need to report them all, the exposed pins you can see from the top side of the board are ODD number pins.

There is only 12 pins on PD?

[budm]

Re: Sharp LC-40LE810UN Zero Power

OK, I just look at the label of the connector below where they print the pin names of the PD connector, I see now that connector is LB, not PD, sorry about that, I have a hard time seeing the pictures clearly.
So at this point since you do have standby Voltage to run the main board, so you need to put connectors back in place and check the PD pin Voltages again then hit the power switch to see if any of PD pins (UR13V, AC_DET, PS-ON, PNL_POW) Voltages change state or not.

[xoicorez]

Re: Sharp LC-40LE810UN Zero Power

.

[xoicorez]

Re: Sharp LC-40LE810UN Zero Power

OK, I just look at the label of the connector below where they print the pin names of the PD connector, I see now that connector is LB, not PD, sorry about that, I have a hard time seeing the pictures clearly.
So at this point since you do have standby Voltage to run the main board, so you need to put connectors back in place and check the PD pin Voltages again then hit the power switch to see if any of PD pins (UR13V, AC_DET, PS-ON, PNL_POW) Voltages change state or not.

The voltages do not change.

[budm]

Re: Sharp LC-40LE810UN Zero Power

So UR13V, AC_DET, PS-ON, PNL_POW all show 0V?

If AC_DET is 0V then that will lock out the other control Voltages, AC_DET should be about 3V for normal operation.

[xoicorez]

Re: Sharp LC-40LE810UN Zero Power

So UR13V, AC_DET, PS-ON, PNL_POW all show 0V?

If AC_DET is 0V then that will lock out the other control Voltages, AC_DET should be about 3V for normal operation.

Sorry, the measurements were incorrect since I didn't connect PD.

UR13V - 12.5 to 0

AC_DET - 0

PS-ON - 2 to 0

PNL-POW - 0.09 to 0.12

[xoicorez]

Re: Sharp LC-40LE810UN Zero Power

I am now reading the old thread and understanding it more. I think I need to replace the optocouplers, PC7703?

Would this work?

They are PC817C but the optocouplers on my board are Cosmo PC817H. They have different CTR based on this PDF?

[budm]

Re: Sharp LC-40LE810UN Zero Power

Sorry, the measurements were incorrect since I didn't connect PD.

UR13V - 12.5 to 0

AC_DET - 0

PS-ON - 2 to 0

PNL-POW - 0.09 to 0.12

I do not understand the reading of XX to YY.
Are you saying when TV is off but plugged into the AC outlet is, I.E. UR13V is 0V when TV is OFF, when TV is on it goes to 12.5V?
Are you also 1005 sure that AC_DET is always at 0V?

[xoicorez]

Re: Sharp LC-40LE810UN Zero Power

I do not understand the reading of XX to YY.
Are you saying when TV is off but plugged into the AC outlet is, I.E. UR13V is 0V when TV is OFF, when TV is on it goes to 12.5V?
Are you also 1005 sure that AC_DET is always at 0V?

Yes, that is correct. When I press the power button when it is plugged into the AC outlet, UR13V jumps to 12.5 but drops to 0. PNL-POW maintains 0.12 then drops to 0.09 when power button is pressed, but goes back to 0.12.

I measured AC_DET again and it is always at 0.

[budm]

Re: Sharp LC-40LE810UN Zero Power

I am now reading the old thread and understanding it more. I think I need to replace the optocouplers, PC7703?

Would this work?

They are PC817C but the optocouplers on my board are Cosmo PC817H. They have different CTR based on this PDF?

Is there CTR marking on the OPTO on your board?

[budm]

Re: Sharp LC-40LE810UN Zero Power

And what DCV do you get when measure between pin 3 and 4 of the OPTO?

[xoicorez]

Re: Sharp LC-40LE810UN Zero Power

Is there CTR marking on the OPTO on your board?

The CTR marking on the opto is H, I believe. It's the bottom letter.

Do you suspect the opto is the issue with those readings on PD?

[xoicorez]

Re: Sharp LC-40LE810UN Zero Power

The CTR marking on my board isn't on the PDF for some reason.