Emerson LF501EM5F shuts down right after turning on.

[Malachi]

Re: Emerson LF501EM5F shuts down right after turning on.

With grey and white disconnected no back lights at all.

[budm]

Re: Emerson LF501EM5F shuts down right after turning on.

So I would need to open it up and see if some of the LEDs don't light up.
But I get the same readings when the led connector is disconnected from the psu.
How can it be an open led string?

You have Voltage feeding on string one to the ANODE then the Yellow Cathode return wire is then connected to the MOSFET and the current sensing resistor to GND, since the string is not open because you see 9V on the Cathode.
Same setup for the Blue (Anode) and Grey (Cathode), Black and White: but you see <1V on the return so the circuit has open circuit (high resistance) on those strings.

[Malachi]

Re: Emerson LF501EM5F shuts down right after turning on.

Updated my post also.

[budm]

Re: Emerson LF501EM5F shuts down right after turning on.

I updated post 40.

[Malachi]

Re: Emerson LF501EM5F shuts down right after turning on.

So I would need to open it up and see if some of the LEDs don't light up.
But I get the same readings when the led connector is disconnected from the psu.
How can it be an open led string?

[budm]

Re: Emerson LF501EM5F shuts down right after turning on.

Looking at the readings on the Grey and the White wires, I would say you have two LED strings with open circuits.
You can prove that buy removing the Grey and the White female connectors from the socket and see you will see the backlights come on for second or not, that is what I would do.

[Malachi]

Re: Emerson LF501EM5F shuts down right after turning on.

It says 100v.
Working psu is right around $50 obo.
$50 on shopjimmy.

[budm]

Re: Emerson LF501EM5F shuts down right after turning on.

OK.
Next, can you tell me the Voltage rating as printed on the body of the cap C1305?

[Malachi]

Re: Emerson LF501EM5F shuts down right after turning on.

Grey and white got as high as those voltages.
Is this looking like a psu problem seeing as how the violates are about the same even with the led disconnected?
Because if you feel it's the psu, I'll just order one.

[budm]

Re: Emerson LF501EM5F shuts down right after turning on.

OK we need to trace out the connection on the Yellow, Grey, and White pins top see if they are LED Cathode return wire of the LED strings or not.

Just to be clear on the Grey wire 'grey drops below 0.86vdc' you said it drops below 0.86VDC but how high did it go up too, that is the important info, same for the White wire.
A quick look at the bottom side of the board, it has 3 Voltage boost converters and 3 PWM Controlled power MOSFET.

Red is the Anode, Yellow is the Cathode return of the first LED string.
Blue is the Anode, Grey is the Cathode return of the second LED string.
Black is the Anode, White is the Cathode return of the third LED string.

[Malachi]

Re: Emerson LF501EM5F shuts down right after turning on.

Red stayed the same, yellow below 1vdc, blue about 79vdc, grey no change, black about 60vdc and white no change.

So about the same.

[budm]

Re: Emerson LF501EM5F shuts down right after turning on.

That looks bad.
Disconnect the LED connector and do the same test again.

[Malachi]

Re: Emerson LF501EM5F shuts down right after turning on.

How do I measure the web the backlight goes off? The voltage keeps dropping, they start dropping as soon as the back lights go off.

[Malachi]

Re: Emerson LF501EM5F shuts down right after turning on.

Red 60vdc, yellow got as high as 9vdc, blue got to 80vdc, grey drops below 0.86vdc when turned on, black 80vdc and white 0.8.1vdc

[budm]

Re: Emerson LF501EM5F shuts down right after turning on.

There are 6 wires in the connector. Top to bottom, red, yellow, blue, grey, black and white.

I updated post 29.

[Malachi]

Re: Emerson LF501EM5F shuts down right after turning on.

There are 6 wires in the connector. Top to bottom, red, yellow, blue, grey, black and white.

[budm]

Re: Emerson LF501EM5F shuts down right after turning on.

OK, thanks for the clarification. We should check the DCV on the LED connector next.
Leave the read probe on one pin at a time then turn on the TV and see what you see on the meter when the backlights come on and when it goes out, then do the same thing on the next pin, and so on.
How many wires are there on that LED connector? I see six wires:

Red = ??? V (Backlights ON), XXX V(Backlights go OFF)
Yellow =
Blue =
Grey =
Black =
White =

[Malachi]

Re: Emerson LF501EM5F shuts down right after turning on.

Sorry, I gues by cycling I meant that it was doing the same thing when powered on.
I realize cycling means continually like I router in a boot loop.
Sorry, I'm new at trying to fix tv's.

[budm]

Re: Emerson LF501EM5F shuts down right after turning on.

Here are the pictures.
I unplugged the led leads from the psu same cycling. With a flashlight I could see it doing the same thing.
I disconnected the main board same thing minus the writing on the screen.
Does that help?

OK, I am confused! So you indicated shutdown but then in that thread you indicate 'Cycling'.
When I see the word 'Cycling' I would be looking for Voltage going on and off or cycling up and down but we are not seeing that.

[Malachi]

Re: Emerson LF501EM5F shuts down right after turning on.

The power led stays on, red, nothing on the screen.
If I press the power button, led blinks, Emerson logo comes on followed by the other message, screen goes black and the power led back to solid red.