Lg 47lk520 no start pulsing led

[Thin film]

Should I consider .70 volts at the error output of the power supply board low? Or hi. I obtained this with the logic board connected and power button pressed and Led pulsing Red.

It should be low by the service info I have.

[budm]

Re: Lg 47lk520 no start pulsing led

We have no idea what the error output of the power supply board is.
How about uploading the pictures of the whole back side of the TV so we can see how all the boards are connected together and the pictures of the power supply connectors so we can see the label names of each pin?

[Thin film]

Re: Lg 47lk520 no start pulsing led

The output from the power supply error line is to be digital low if there is no errors.
It is to be digital hi if there is some type of error.

So again should I consider .70 volts digital low in an Lg model indicating no error. Or should I consider it digital hi indicating an error.

I want to know what the limits are to set digital hi or low in the error line from the power supply.

[budm]

Re: Lg 47lk520 no start pulsing led

I do not see the pictures of the boards so I cannot tell what that pin is on the power supply board, if it is an input pin or out put pin. Per diagram, pin 24 on the main board for ERROR pin has 0 Ohm resistor R475 connected to that pin to GND, I do not know if that pin is connected to the power supply ERROR pin or not, no pictures see. There are more than just one Voltages that need to be checked.
Do you have that page of your service manual to tell us what is that error signal is for? 5V logic >2.7V = HI. Do you know if this is 5V logic or 3.3V logic?

https://learn.sparkfun.com/tutorials/logic-levels

[Thin film]

Re: Lg 47lk520 no start pulsing led

Attempting to post photo. Need to switch between three devices to do so give me a minute or so.

[Thin film]

Re: Lg 47lk520 no start pulsing led

I think its 3.3 logic but im not 100%

First photo overall 2nd photo at power supply.

I guess I could fire up the power supply by itself and read the error volt at the power board.

Could not post the photos from where i was earlier.

[budm]

Re: Lg 47lk520 no start pulsing led

Check the resistance between the ERROR pin of the power supply board and the ERROR PIN 24 of the main board to see if it has direct connection. Also check the the resistance of that pin 24 of the main board and GND to see if it shows < 1 Ohms. At this point I am not even sure if the diagram matches your board or not.

[Thin film]

Re: Lg 47lk520 no start pulsing led

R475 does not exist on my board. Hi resistance it ground. Also verified that r475 missing. Spot exists but not populated. I've looked at these boards a lot thats how I found it so fast.

Pin 24 to pin 24 direct connection ,
continuity.

[Thin film]

Re: Lg 47lk520 no start pulsing led

Oh and pin 24 at main board is hi resistance to ground.

[Thin film]

Re: Lg 47lk520 no start pulsing led

The drawing you have appears to mimick the one it have. Not 100% accurate, but fairly good lots of options. Most of the majors exist and are as shown.

[budm]

Re: Lg 47lk520 no start pulsing led

R475 does not exist on my board. Hi resistance it ground. Also verified that r475 missing. Spot exists but not populated. I've looked at these boards a lot thats how I found it so fast.

Pin 24 to pin 24 direct connection ,
continuity.

OK, if you at this diagram:
https://www.badcaps.net/forum/attach...2&d=1433288508

You can see the Collector (output) of Q405 has resistor R415 (100 Ohms) to goes to the pin 18 INVERTER_ON (output) for turning on the inverter board, then you can also see resistor R425 (100 Ohms) which is also connected to the Collector of Q405, the other end of this resistor is connected to pin 24 (ERROR pin).
Q405 is normally on so the Collector DCV will be < 1VDC, when the power switch is activated then the processor will turn off Q405 which will cause the Collector to go high toward 3.3V (>2V = HI).
So check and see if that how those resistors are connected and in place or not.