Funai (Emerson) LF501EM4F not turning on

[smacko]

Hi all,

I have a Funai (Emerson) LF501EM4F 50" LCD that will not power on

When plugged in:

1. The red light blinks 6 times
2. I hear a buzz from the speakers
3. red light goes constant on

Pressing the power button and I see the same cycle.

I tested the below pins on the power board. The readings were the same when

• The power board was disconnected to the control board
• The power board was connected to the control board but all other connections to the control board were unplugged
• The power board was connected to the control board with the other 3 connectors attached

These results were from plugging the TV in.
all+3.3v -- 3.3 -- stays at 3.3
Amp+137 -- 12.49 -- after about 7 seconds it drops to 6.45
P-on+21v -- 21.1 -- after about 7 seconds it drops to 11.63
P-on_h2 -- 3.17 -- after about 7 seconds it drops to 0

I would appreciate any help. I am not a technician but my wife says I follow directions well .

Thanks,

Doug S

[capwizard]

Re: Funai (Emerson) LF501EM4F not turning on

First test LED screen, to isolate the common LCD screen caused problems.

https://www.badcaps.net/forum/showthread.php?t=59209

[CapLeaker]

Re: Funai (Emerson) LF501EM4F not turning on

The PSU pic is too blurry for me, but see if there is something like protect 3 (the protect line for the LED), measure that.

[smacko]

Re: Funai (Emerson) LF501EM4F not turning on

Hi again,

Sorry for the delay in getting back to this.

Your first question:
First test LED screen, to isolate the common LCD screen caused problems.
https://www.badcaps.net/forum/showthread.php?t=59209

I get 0.0 on each pair copying the setup in your pictures on the referenced thread.
I also tested just the socket and back-probed the plug with it plugged into the socket
Both showed 0.0
** I am not sure about what I am doing, I not sure where the juice is supposed to be coming from

Second question:
I checked protect-3

When the TV is plugged in it shows 0.43
Stays there for 3 seconds then goes to 0.05
At 9 seconds it goes back to 0.43 for a moment and then to 0.0
At the 9 second mark you also hear a distortion from the speaker.

Thanks,

[CapLeaker]

Re: Funai (Emerson) LF501EM4F not turning on

That's bad, if the protect is low. If you plug the TV in and try to turn it on, how much DC volt are you getting on the main filter capacitor?
Attached is a service manual.

[smacko]

Re: Funai (Emerson) LF501EM4F not turning on

I'm a bit out of my skill set here. I went over the service manual but could not find anything looking specifically for 'main filter capacitor'.

I attached a shopjimmy image of the power board. Can you mark a spot?

[CapLeaker]

Re: Funai (Emerson) LF501EM4F not turning on

It's a big high voltage capacitor in the primary. In your case the big black one in the middle of the board.

[smacko]

Re: Funai (Emerson) LF501EM4F not turning on

I took readings at pfc_vout

With the BL and Control Board connected
Both when plugging the TV in and when pressing the on button
I get 217 dcv for about 8 seconds and then a jump down to 171

Without the BL and Control Board connected
I get 171

[petehall347]

Re: Funai (Emerson) LF501EM4F not turning on

buzz from speakers makes me wonder .. see if audio chip is getting hot .. or speakers might be getting hot .

[CapLeaker]

Re: Funai (Emerson) LF501EM4F not turning on

171V while off is correct. 217V DC while on, is wrong. It should be much more than that. You can unhook everything but the back lights on the PSU and force the PSU and the back light on by soldering a 1k ohm resistor from 5V STBY to BLon and another 1k resistor from 5V STBY to PSon. When you plug the PSU in, all voltage rails should be up and the back lights should be on.

[smacko]

Re: Funai (Emerson) LF501EM4F not turning on

Would this be the correct resister?
https://www.radioshack.com/products/...-resistor-pk-5

There is a Radio Shack that I can hit on my way home from work if so.

I would soder this on the top side of the board to the test wires?

[vinceroger69]

Re: Funai (Emerson) LF501EM4F not turning on

yes those resistors are fine to use.

[jayjoesph]

Re: Funai (Emerson) LF501EM4F not turning on

171V while off is correct. 217V DC while on, is wrong. It should be much more than that. You can unhook everything but the back lights on the PSU and force the PSU and the back light on by soldering a 1k ohm resistor from 5V STBY to BLon and another 1k resistor from 5V STBY to PSon. When you plug the PSU in, all voltage rails should be up and the back lights should be on.

Hi i have similar issue with emerson 50 the red light just flashs every 10 seconds I have used resistors to ps -on and -bl -sw and bl- adj leds power up and stay on. red led flashs same with/without ps forced being forced on . I how ever get no voltage reading at pfc_vouts . Can i do a test to check that the leds are fine? I have checked diodes for shorts non open what should i check for next

Have tried no ir board still flashs

all 3volt=3 volt all time
+21 volt jumpers read 11-12 off 21 ON when forced on buttons/remote no effect
protect 3 is under a volt unless forced on

[budm]

Re: Funai (Emerson) LF501EM4F not turning on

Hi i have similar issue with emerson 50 the red light just flashs every 10 seconds I have used resistors to ps -on and -bl -sw and bl- adj leds power up and stay on. red led flashs same with/without ps forced being forced on . I how ever get no voltage reading at pfc_vouts . Can i do a test to check that the leds are fine? I have checked diodes for shorts non open what should i check for next

Have tried no ir board still flashs

all 3volt=3 volt all time
+21 volt jumpers read 11-12 off 21 ON when forced on buttons/remote no effect
protect 3 is under a volt unless forced on

Did you measure the DCV right between the two legs of the main filter cap?
What did you use for GND ref. for your meter?

[jayjoesph]

Re: Funai (Emerson) LF501EM4F not turning on

Did you measure the DCV right between the two legs of the main filter cap?
What did you use for GND ref. for your meter?

DCV? i only I checked pfc_out to a ground (pin/jumper?) near the led 6pin connecter and a pfc_out ground . is that what you mean? I checked the big center cap 400v100uf with a mega tester read 133uf have a fluke meter 85 to use for testing

[jayjoesph]

Re: Funai (Emerson) LF501EM4F not turning on

Sorry ment 400wv . I measured it board plugged in only 172.5v 217v when ps-on

[budm]

Re: Funai (Emerson) LF501EM4F not turning on

The PFC Voltage will not be 380~400 VDC on this power supply board, more likely 250~280 VDC range, that is why the cap is only rated at 400VDC.
BTW, normal condition the PROTECT 3 should around 3 VDC, <1V indicate error in the backlights circuit.

[jayjoesph]

Re: Funai (Emerson) LF501EM4F not turning on

Is my pfc okay being 217.5v? Should PROTECT 3 have voltage with PS off? When i jumped PS_ON and BL-sw and Bl-adj PROTECT 3 shows around 2.6

[budm]

Re: Funai (Emerson) LF501EM4F not turning on

I would say 217.5V is low, the PROTECT3 should be 3V when TV is turn on, look at the schematic.

[jayjoesph]

Re: Funai (Emerson) LF501EM4F not turning on

ill be back in a few hours but can i bypass protect 3 with grounding out the the timer? I dont wanna fry anything tho more