Vizio VW42LFHDTV10A - Only the logo light comes on :(

[drpj23]

Re: Vizio VW42LFHDTV10A - Only the logo light comes on

It had a short lived life lol......I am going to shoot this thing.

Anyways, back to the original problem (besides inverters)

So I will retest components and I do not believe I tested the DC-DC converters since it started working so I'll do that too.

Well I at least know the inverters work and T-CON can work.

I'll see too if shorting U20 will work again.

[Y2KEDDIE]

Re: Vizio VW42LFHDTV10A - Only the logo light comes on

I hope this is an appropriate point to jump in your thread:

This past weekend I came across a LED Flat Screen TV, curbside Naturally I could not pass up this opportunity to explore new technology.
It is a model VISO VW42L FHDTV10A. S/N: LQPBYGKO303318, and set # is 10235072022.

The power supply board looks nothing like the one in your postings. There are only 4 connectors on the PS board: CN101(AC Power),CN203,CN204 (Backlight outputs), and CN201 (15 Pin connector).

Experience has taught me when something doesn't power up, no lights, sounds etc., I look to the power supply.

I checked the fuse and some voltages at random points as I have no schematic. I found the incoming line is rectified thru a bridge and this section of the board has un-regulated line voltage rectified.

There is a 15 pin Molex connector labeled CN201.
The board silk screening is a little confusing:
From right to left:

14 Inverter on/off
13 Dim
12}
11} +5V
10}

9}
8}
7} GND
6}
5}

4}
3} +12V
2}

1 PS on/off

I'm trying to test this board as a stand-alone device; not connected to the other circuitry. When connected or not connected I read +5VDC at pins 10,11, &12 with respect to ground (5,6,7,8,&9),but nothing at 2,3,&4, or any other pins.

When connected, I press the power on/off button but no change at any pins.
I surmise when not connected to the rest of circuitry the board is not getting a power up signal. I'm wondering : should I ground pin 1 and /or 14 to start a sequence? I'm afraid of damaging the board further if this is incorrect.

Do you think I should be reading the +12v regardless of in 1 and/or 14 state?
Any suggestions?

The flow chart is not much help, and no schematic on-line thus far. I've looked at everything posted here thus far.

Thanks,

Eddie

[budm]

Re: Vizio VW42LFHDTV10A - Only the logo light comes on

Invereter on/off, DIM, and PS_ON signals are generated by the main board and they will be present when power switch is activated. Please read the basic troubleshooting guide.
PS_ON: <1VDC = OFF, >2.5VDC = ON.

[Shinju]

Re: Vizio VW42LFHDTV10A - Only the logo light comes on

IMO, I would start a new thread with photos of your panel if its a different build with the same model numer..

[Y2KEDDIE]

Re: Vizio VW42LFHDTV10A - Only the logo light comes on

Thanks Budm. I read your excellent guides. First I will get some proper loads for the supplies: Inverter output, 5v and 12V as you suggested. When evereything is connected in the set, I don't get any readings on the ps on/off pin, even when I press the on /off button. I was hoping once I have the loads attached, I could extrenally apply 2.5VDC to see if it will power up. I fear the other (controller ) board may be trhe problem.

[budm]

Re: Vizio VW42LFHDTV10A - Only the logo light comes on

If you are not getting the PS_ON from the main board, then you should start checking the Voltage regulators and fuses on the main board next, very common failure for VIZIO.
You should start a new thread with good pictures of the boards since this model has so many different version.
Try searching the forum using 'Vizio VW42LFHDTV10A' you will see lots of info regarding the regulators problems.