VIZIO VL320M Dark Screen,has sound

[geraposi]

Vizio VL320M Has sound with cable input but screen doesn't light. Vizio LOGO turns white at turn on. Power board voltages are below. I saw on another thread that they wanted to know about 24v, I don't see any 24v feeds on this board. Voltage across 47ufd 450v caps is 387v. Not sure on higher voltage going to back of screen. I would appreciate any help I can get..Thanks, Geraposi

DIM, 2.8v
INV-ON, 3.3v
VBR-A, .6v

ON-OFF, 3.2v
12v, 12.1v
12v, 12.1v
12v, 12.1v
GND
GND
GND
GND
GND
ST/5v, 5.1v
ST/5v, 5.1v
ST/5v, 5.1v

[tom66]

Re: VIZIO VL320M Dark Screen,has sound

Picture of the power board?

[geraposi]

Re: VIZIO VL320M Dark Screen,has sound

Hope this is clear. Thanks for the quick reply,

[budm]

Re: VIZIO VL320M Dark Screen,has sound

The power supply-inverter board is getting correct signals from the main board for the backlights. Pictures of the bottom side of the board?
http://www.shopjimmy.com/vizio-0500-...t-inverter.htm

[geraposi]

Re: VIZIO VL320M Dark Screen,has sound

I hope you were talking about the back of the power board...

[tom66]

Re: VIZIO VL320M Dark Screen,has sound

Using that photo these resistors highlighted appear to be for fusing the inverter feed. Test them on an ohm-meter - they should show very low ohms (<10 ohms, I'd guess.)

[geraposi]

Re: VIZIO VL320M Dark Screen,has sound

The resistors you circled are color coded, red red orange, 22k. They are in parallel with each other and measure close to 11k.

[tom66]

Re: VIZIO VL320M Dark Screen,has sound

D'oh - that's my error. Try this resistor instead.

[geraposi]

Re: VIZIO VL320M Dark Screen,has sound

That is F601. It is good. You may be talking about R608 and R618, two resistors thatare hooked in parallel and connect to the negative terminals of the two 47ufd 450v caps, they are very low resistance and measure less than ohm

[budm]

Re: VIZIO VL320M Dark Screen,has sound

That F601 (Fusible resistor) is for feeding the B+ to the whole circuits (inverter and the rest of the power supply), at least the power MOSFETs for the inverter is not shorted out. It can be the PWM circuit that is not driving the Gate drive transformer.

[geraposi]

Re: VIZIO VL320M Dark Screen,has sound

budm, Did I have the back side of the correct board?

[budm]

Re: VIZIO VL320M Dark Screen,has sound

Yes. The board is only $34.

[geraposi]

Re: VIZIO VL320M Dark Screen,has sound

Do you recomend buying a board over fixing and you do mean the power board don't you.

[budm]

Re: VIZIO VL320M Dark Screen,has sound

You can try troubleshooting down to components level which very time consuming due to no schematic disgram, by the time you buy proper tools for SMD repair and parts, that can be closed to the price of the new board. The bad thing is that we do not know if you have bad lamps problem or not.
This board is power supply-inverter combo board.

[geraposi]

Re: VIZIO VL320M Dark Screen,has sound

what is the voltage going to the lamps?

[Alastair E]

Re: VIZIO VL320M Dark Screen,has sound

what is the voltage going to the lamps?

1500-2500, AC high frequency.....

DO NOT attempt to measure!

[geraposi]

Re: VIZIO VL320M Dark Screen,has sound

BIG BIG Thank you. You probably just saved my meter... What is the likelyhood of the problem being a bulb? Which is the more common failure the bulb or board?

[geraposi]

Re: VIZIO VL320M Dark Screen,has sound

What is the more likely to be the problem causing no backlight, the power/invertor board or bulbs?

[budm]

Re: VIZIO VL320M Dark Screen,has sound

This is just speculation: if some of the lamps/or lamp are bad, you should be able to see at least some of good the lamps flash on long enough for the error detection circuit to kick in and shut down the inverter circuit, but if you do not even see the lamps flash on once for sure, then more likely the inverter circuit is not working.

[geraposi]

Re: VIZIO VL320M Dark Screen,has sound

That is very good reasoning budm, I have never seen enen a flicker. Thank you for your help, I will order a board today...