Emerson LF501EM4F turn on then off.

[CapLeaker]

Re: Emerson LF501EM4F turn on then off.

Im trying to jump it with a resistor that I'm reading 1.032 but I'm getting 3.3v at the end but once I touch the p-on_h2 it drops down to 0.57v

Must be a bad resistor. Some resistors go high in value if there is current going through it, but measure fine out of circuit or if the unit is turned off. I've had that happen before.

[erickeri1234]

Re: Emerson LF501EM4F turn on then off.

When doing the above test did the backlights come on and stay on?

I disconnected every from the PS board. But I will plug the backlight in and see.

[erickeri1234]

Re: Emerson LF501EM4F turn on then off.

Must be a bad resistor. Some resistors go high in value if there is current going through it, but measure fine out of circuit or if the unit is turned off. I've had that happen before.

Yea something was up with it. I grabbed a different resistor 1.2xx and I got some readings.

[erickeri1234]

Re: Emerson LF501EM4F turn on then off.

When doing the above test did the backlights come on and stay on?

OK tested it with the backlight connected to the PS board. The back light doesn't come on.
But it does come on when main board is connected. Weird!!!

[CapLeaker]

Re: Emerson LF501EM4F turn on then off.

yeah... you only have PSon jumped to fire up. You would have to do the same thing to BLon (backlights). There is nothing wrong with your PSU.

[erickeri1234]

Re: Emerson LF501EM4F turn on then off.

yeah... you only have PSon jumped to fire up. You would have to do the same thing to BLon (backlights). There is nothing wrong with your PSU.

It's got to be the main then right. It does seem like it.

[erickeri1234]

Re: Emerson LF501EM4F turn on then off.

Ordered the main board today. Will post out come

[erickeri1234]

Re: Emerson LF501EM4F turn on then off.

UPDATE!!!
Git the main board in from SJ, installed it and it is doing the samething. Turns on for about 5 to 8 seconds then right off. So I ordered a PS board samething on then right off... should I RMA the main board??

[CapLeaker]

Re: Emerson LF501EM4F turn on then off.

measure the voltages on the back light led strings.

[erickeri1234]

Re: Emerson LF501EM4F turn on then off.

measure the voltages on the back light led strings.

Hard to measure no diagram on board.
It does it even when everything is unplugged . Just power to main.

[CapLeaker]

Re: Emerson LF501EM4F turn on then off.

So when the TV comes on for 8 seconds the TV acts normal (you can see picture on the LCD) and then the TV turns fully off? That is a main board problem in my book. So verify the PSon pin on the power supply again. If the PSon voltage drops out, it is the main board. PSon is generated on the main board. Try the same thing with the back lights unplugged, then with the Tcon unplugged. Are there 2 ribbon cables going to the tcon?

[erickeri1234]

Re: Emerson LF501EM4F turn on then off.

So when the TV comes on for 8 seconds the TV acts normal (you can see picture on the LCD) and then the TV turns fully off? That is a main board problem in my book. So verify the PSon pin on the power supply again. If the PSon voltage drops out, it is the main board. PSon is generated on the main board. Try the same thing with the back lights unplugged, then with the Tcon unplugged. Are there 2 ribbon cables going to the tcon?

Yea tv will power up I see the Emerson logo then for split second I can see the channel, then the tv goes turns off fully when speakers make like a small popping noise like the board is shorted. It does it with everything connected and when I disconnect everything. I just tested the power supply again samething.
PS_ON-H2 ..... 3.2v then drops to 0.0v when it shuts down
P-ON+21V.... 21v then to 11.5v when it shuts down
All+3.3v..... 3.279v there all the time.

[erickeri1234]

Re: Emerson LF501EM4F turn on then off.

One ribbon going to the tcon.

[erickeri1234]

Re: Emerson LF501EM4F turn on then off.

Pic

[CapLeaker]

Re: Emerson LF501EM4F turn on then off.

Where does that ribbon on the bottom left corner on the main board go? It looks like it goes to the Tcon for me?

[erickeri1234]

Re: Emerson LF501EM4F turn on then off.

Small ribbon goes to the ir board.

[SLK001]

Re: Emerson LF501EM4F turn on then off.

The description sounds like you have bad LEDs in your backlight. There appears to be more than one string of LED power. When you turn the TV on, the working strings will light up until the chip controlling the bad string flags a failure mode, shutting down the entire set to protection mode.

The exact same problem presented itself to me with a VIZIO set. I struggled thinking that it was a PS problem for two days, then finally realizing that the LED FAULT line was being pulled low (indicating a fault). It is very slow to respond (over 6+ seconds), thus giving the impression that the backlights are okay. However, the backlights were NOT okay and a teardown of the panel showed two LEDs out in one of the strings. I am waiting for LEDs to replace them.

[erickeri1234]

Re: Emerson LF501EM4F turn on then off.

The description sounds like you have bad LEDs in your backlight. There appears to be more than one string of LED power. When you turn the TV on, the working strings will light up until the chip controlling the bad string flags a failure mode, shutting down the entire set to protection mode.

The exact same problem presented itself to me with a VIZIO set. I struggled thinking that it was a PS problem for two days, then finally realizing that the LED FAULT line was being pulled low (indicating a fault). It is very slow to respond (over 6+ seconds), thus giving the impression that the backlights are okay. However, the backlights were NOT okay and a teardown of the panel showed two LEDs out in one of the strings. I am waiting for LEDs to replace them.

Yea I understand that but it does it even went I have the back lights disconnected.
I have only power to the ps board and the ribbon from ps to the main and it still shuts down.
And if I jump 3.3v to ps-on the ps board stays on all with correct volts.
It just seems like a bad main board. But it is from shopjimmy.

[SLK001]

Re: Emerson LF501EM4F turn on then off.

Yea I understand that but it does it even went I have the back lights disconnected.
I have only power to the ps board and the ribbon from ps to the main and it still shuts down.
And if I jump 3.3v to ps-on the ps board stays on all with correct volts.
It just seems like a bad main board. But it is from shopjimmy.

You should get an LED FAIL signal with the backlights disconnected, too (open circuit detected).

[budm]

Re: Emerson LF501EM4F turn on then off.

No cable between the power supply board and the main board, LED connector in place, do the resistor jumper for the PS-ON (P-ON-H2) as before, then another resistor between the jumper J106/ BL-SW and the 3.3V to force the backlight on, see if the backlights will stay on.
Pictures provided by shopjimmy.
http://www.shopjimmy.com/emerson-a3a...pply-unit.htm#
Emerson A3AU0MPW-001 Power Supply for LF501EM4 / LF501EM4F