Vizio E3D420VX No picture, Power light blinks on then no power

[tannenbaum]

A neighbor put this on the curb for trash yesterday, but I want to take a chance at fixing it. It didn't rain yesterday, so I don't chalk my current problem up to weather damage.

When I press the power button, two things happen:

1. The white power indicator light in the lower right of the front bezel blinks on for a second, then turns off.
2. A strange sound comes from the power board. It’s a click followed by a short, high-pitched sound. I recorded the noise and included it as a ZIP attachment. There are 3 noises in the audio clip: pressing the power button, a click from the power board, and a high-pitched sound from the power board.

I have limited knowledge when it comes to troubleshooting these things, but I took hi-res photos to aid you all as much as possible. Based on what I’ve read in other threads, I think you all may need some more data to reach a conclusion, so please let me know what you need. Thank you for your help!

-Andrew

[budm]

Re: Vizio E3D420VX No picture, Power light blinks on then no power

So what kind of tools do you have? Good at soldering, especially the surface mounted devices?
Your power supply/inverter board:
http://www.shopjimmy.com/vizio-0500-...pply-unit.htm#

The section you are hearing the noise from are the PFC Voltage booster circuit and the Inverter circuit.

[tannenbaum]

Re: Vizio E3D420VX No picture, Power light blinks on then no power

My friend who is much more handy with electronics offered to help me, and he has a variety of tools. I know he has a multimeter and soldering iron; are there other tools I should ask if he has? He's had quite a bit of experience with soldering, but I'll have to ask if he's done anything with surface mounted devices.

Thank you for your insight. Given my comments, do you recommend doing any testing, or do you conclude I should replace the power supply/inverter board entirely?

[budm]

Re: Vizio E3D420VX No picture, Power light blinks on then no power

You will need to do real close visual inspection of the power supply board, look at both sides of eh board for damaged parts, bad solder joints, etc.
Then you will need to do DCV testing on the connectors of the power supply board, the pin of the connector (the one that goes to the main board), you need to test them when TV is plugged in but not turned on, then when the power switch is activated.
Write down the Voltage readings, follow by the pin number and the pin names so we can see what they are.
Pictures provided by shopjimmy.

[tannenbaum]

Re: Vizio E3D420VX No picture, Power light blinks on then no power

Didn't see any bad solder joints or damaged parts. We tested the 14 connectors of the power supply board, CN201 according to the power supply board photo you provided.

Plugged in but not turned on:
Pin 1 (+5.1VSB): 5.28
Pin 2 (+5.1VSB): 5.28
Pin 3 (+5.1VSB): 5.28
Pin 4 (SGND): -0.001
Pin 5 (SGND): -0.001
Pin 6 (SGND): -0.001
Pin 7 (SGND): -0.001
Pin 8 (12V): -0.001
Pin 9 (12V): -0.001
Pin 10 (12V): -0.001
Pin 11 (PSON): 0.098
Pin 12 (ON/OFF): 0.006
Pin 13 (LAMP): 0
Pin 14 (DIM): -0.007

Plugged in and turned on:
Pin 1 (+5.1VSB): 5.16
Pin 2 (+5.1VSB): 5.16
Pin 3 (+5.1VSB): 5.16
Pin 4 (SGND): -0.019
Pin 5 (SGND): -0.019
Pin 6 (SGND): -0.019
Pin 7 (SGND): -0.019
Pin 8 (12V): 12.3
Pin 9 (12V): 12.3
Pin 10 (12V): 12.3
Pin 11 (PSON): 1.3
Pin 12 (ON/OFF): 0.026
Pin 13 (LAMP): showed 2.1, then 3.0, then 0; jumped around
Pin 14 (DIM): showed 2.1, then 3.0, then 0; jumped around

[budm]

Re: Vizio E3D420VX No picture, Power light blinks on then no power

"Pin 12 (ON/OFF): 0.026" The main board is not sending the BL-ON (Inverter ON) sinal turn turn on the backlights circuits.
You need to check DCV between the two legs of the main filter cap to see if it has close to 400VDC or not.

[tannenbaum]

Re: Vizio E3D420VX No picture, Power light blinks on then no power

Readings for the main filter cap, what I assume is the biggest cap, C804.

Plugged in but not turned on:
Neg terminal to ground: -62.7
Pos to ground: 97.3
Neg to Pos: 163

Plugged in and turned on:
Neg terminal to ground: jumps to -54
Pos to ground: 331 at its highest, then goes down
Neg to Pos: 392, for a second

[retiredcaps]

Re: Vizio E3D420VX No picture, Power light blinks on then no power

Readings for the main filter cap, what I assume is the biggest cap, C804.

Plugged in but not turned on:
Neg terminal to ground: -62.7
Pos to ground: 97.3
Neg to Pos: 163

Plugged in and turned on:
Neg terminal to ground: jumps to -54
Pos to ground: 331 at its highest, then goes down
Neg to Pos: 392, for a second

On the hot side , the negative leg of the large filter capacitor is your ground.

[budm]

Re: Vizio E3D420VX No picture, Power light blinks on then no power

My post 6 instruction:
You need to check DCV between the two legs of the main filter cap to see if it has close to 400VDC or not.

[tannenbaum]

Re: Vizio E3D420VX No picture, Power light blinks on then no power

My post 6 instruction:
You need to check DCV between the two legs of the main filter cap to see if it has close to 400VDC or not.

I apologize for not understanding.

What do you mean by checking the DCV between the legs? I understood that to mean "make contact with both legs and measure the voltage," but I'm sure I misinterpreted what you wrote. Are you saying that the multimeter shouldn't make contact with the legs? Just looking for clarification before I take another reading. Thank you.

[budm]

Re: Vizio E3D420VX No picture, Power light blinks on then no power

Black probe on the negative leg of the cap, Red probe on the positive leg of the cap then check the DCV when the power switch is activated, make sure not to let the probes slip on you and do not touch anything withe your hands/body, you are working in the deadly side of the circuit.

[tannenbaum]

Re: Vizio E3D420VX No picture, Power light blinks on then no power

Thanks for clarifying! The DCV for that reading is 392.

[budm]

Re: Vizio E3D420VX No picture, Power light blinks on then no power

OK, the PS-ON from the main board is OK otherwise you will have the boosted Voltage to run the backlights inverter section, but the main board is not sending the BL-ON signal to turn on the backlights inverter circuit.
You can force on the backlights by remove the wire of the pin 12 (ON/OFF) pin first (you must do this because we do not want to back feed the forced Voltage back to the main board) then use a 300~1K Ohms resistor 1/4 W between the 5.1VSB pin and the pin 12 on the board. Plug the TV into the outlet and see you can get the backlights on and see the pictures on the screen if the main board and the T-CON boards are OK.

[fzabkar]

Re: Vizio E3D420VX No picture, Power light blinks on then no power

Readings for the main filter cap, what I assume is the biggest cap, C804.

Neg to Pos: 392, for a second

Doesn't this mean that the PFC circuit is going into protection shutdown?

If so, could this be due to the low (?) PSON voltage?

[budm]

Re: Vizio E3D420VX No picture, Power light blinks on then no power

Doesn't this mean that the PFC circuit is going into protection shutdown?

If so, could this be due to the low (?) PSON voltage?

OK, I re-read his reply again and understand his measurement now.:
Plugged in and turned on:
Neg terminal to ground: jumps to -54
Pos to ground: 331 at its highest, then goes down
Neg to Pos: 392, for a second

Now we need to find out if the PS-ON did jump up higher than 1.2V first or not.
The switched 12V should also drops out since the same PS-ON is used to turn on the 12V switched MOSFET Q910.

[tannenbaum]

Re: Vizio E3D420VX No picture, Power light blinks on then no power

PS-ON did jump higher than 1.3V at first.

What other info can I provide you with?

You can force on the backlights by remove the wire of the pin 12 (ON/OFF) pin first (you must do this because we do not want to back feed the forced Voltage back to the main board) then use a 300~1K Ohms resistor 1/4 W between the 5.1VSB pin and the pin 12 on the board. Plug the TV into the outlet and see you can get the backlights on and see the pictures on the screen if the main board and the T-CON boards are OK.

Do you still want me to do this test?

[tannenbaum]

Re: Vizio E3D420VX No picture, Power light blinks on then no power

Thread bump. What's the next step I should take in this repair?

[budm]

Re: Vizio E3D420VX No picture, Power light blinks on then no power

PS-ON did jump higher than 1.3V at first.

What other info can I provide you with?



Do you still want me to do this test?

Yes.

[robhink]

Re: Vizio E3D420VX No picture, Power light blinks on then no power

I'm having the exact same problem with my E3D420VX. Was a solution ever found? Should I just replace the main board or power supply board?

[tannenbaum]

Re: Vizio E3D420VX No picture, Power light blinks on then no power

Okay, I did the test as described. The backlight came on for about a second when I pressed the power button, but then it shut off. No pictures or images showed.