Vizio 32 inch (VA320M) Eco 1080p black screen

[KuDaH]

Re: Vizio 32 inch (VA320M) Eco 1080p black screen

U702 -> pcb designation
L161 -> line 1 of the IC
903T63 -> line 2 of the IC
pin 1 = .2 mv
pin 2 = 3.283 V
pin 3 = 4.96 V


U701 -> pcb designation
17809 -> line 1 of the IC
94 34 -> line 2 of the IC
pin 1 = 11.88 V
pin 2 = 8.5 mv
pin 3 = 9.06 V


readings off the two voltage regulators above.. pic below... still trying to look at the data sheet here and see if these readings are good or not.

[KuDaH]

Re: Vizio 32 inch (VA320M) Eco 1080p black screen



reading in the pic but to small...ha ha
Voltage regulators circled in red on board

U702 -> pcb designation
L161 -> line 1 of the IC
903T63 -> line 2 of the IC
pin 1 = .2 mv
pin 2 = 3.283 V
pin 3 = 4.96 V


U701 -> pcb designation
17809 -> line 1 of the IC
94 34 -> line 2 of the IC
pin 1 = 11.88 V
pin 2 = 8.5 mv
pin 3 = 9.06 V

still trying to check the data sheet and see what I have here for these readings. confusing.

[tom66]

Re: Vizio 32 inch (VA320M) Eco 1080p black screen

Both of those regulators are good.

This is not a "typical" Vizio TV which are usually designed by AmTRAN and assembled in Mexico. It is a Unihan TV, an OEM in China.

It is quite possible that it has the common eeprom bug but I believe that only affected the AmTRAN models.

[KuDaH]

Re: Vizio 32 inch (VA320M) Eco 1080p black screen

hmmm .... Ok

maybe a new motherboard purchase? if the problem is on that board...

you took me a long way, kinda fun to investigate this.

Thanks

[KuDaH]

Re: Vizio 32 inch (VA320M) Eco 1080p black screen

One more question, if you don't mind.

We figured out the on/off signal was incorrect for the lights. Due to a signal from the main board via the power supply. If that is correct, how does the "no sound" figure into this? Is the sound enabled after the requirements of the lights are met?

[tom66]

Re: Vizio 32 inch (VA320M) Eco 1080p black screen

Quite possibly the processor crashes after the Vizio logo is shown. Maybe it always blanked the backlights just before then or when it changed modes. Many TVs do this. It's somehow getting stuck on the boot up process. Apparently the system flash gets easily corrupted on these models. And if the processor has crashed, it won't process the sound. These TVs are a lot like computers. They can lock up and freeze too.

[KuDaH]

Re: Vizio 32 inch (VA320M) Eco 1080p black screen

ok, thanks for your help. much appreciated.

[tom66]

Re: Vizio 32 inch (VA320M) Eco 1080p black screen

I just hope you can fix it and save it from going to waste.

[budm]

Re: Vizio 32 inch (VA320M) Eco 1080p black screen

From the look of the power supply board, the 12v is also generated by the same transformer that generates the 24v, you can see two rectifiers mounted on the same heatsink, very common to have 12v and 24v runs by the same transformer. That is why you do not have sound.

[tom66]

Re: Vizio 32 inch (VA320M) Eco 1080p black screen

Bud, in this case, the OP has good 24V and 12V, and they are staying up. The main board is turning the backlight off using the ON/OFF control (not PSON.)

[budm]

Re: Vizio 32 inch (VA320M) Eco 1080p black screen

By the way, there are four switching power supplies on the main board that should be checked also.
I believe there is another thread on this same model.

[budm]

Re: Vizio 32 inch (VA320M) Eco 1080p black screen

OK, I missed that part, it is the BL_on that went away, not the PS_ON.

[KuDaH]

Re: Vizio 32 inch (VA320M) Eco 1080p black screen

I'm gonna have to read a bit to check the swithching power supplies. But I do see them in the picture. Thanks fro the .pdf Bud

The small control board at the top has a voltage regulator on it too. I should check that too.

By the way there is a connector on this tv that goes nowhere... refered to in white outline. this connector just gets taped down under the metal tape. kida strange for just a ground? off the main board.

[/IMG]

[budm]

Re: Vizio 32 inch (VA320M) Eco 1080p black screen

That is strange, I see that it goes under the foil, do you see what is under the foil?

[KuDaH]

Re: Vizio 32 inch (VA320M) Eco 1080p black screen

this is the connection on the other end, under the foil



Also checked the voltage regulator on the small control board (top center)



Values tested with unit turned on, obviously. strange

[budm]

Re: Vizio 32 inch (VA320M) Eco 1080p black screen

There are 3 switching power supplies (three round inductors) that I can see on this T-CON board. There is also a white surface mounted fuse, it should have either 5v or 12v feeding it.

[KuDaH]

Re: Vizio 32 inch (VA320M) Eco 1080p black screen



If this is the fuse you are refering too... I have about 12V on it when the TV turns on then after the cycle with the splash screen the lights go out and the votage drops to almost zero.

[budm]

Re: Vizio 32 inch (VA320M) Eco 1080p black screen

Yes, that is the fuse, there is a MOSFET that is switched on and OFF by the main board. So right now the main board cuts out the signals that turn on the inverter and the T-CON board. At this point, you need to fix or replace the main board.

[KuDaH]

Re: Vizio 32 inch (VA320M) Eco 1080p black screen

Thats great news. well kinda... at least I know which board it is, lol.
Now to find one....fix, ok but kinda tough...replace might be a better option for me. Got a good resource for the parts? just asking.
I am sure I can find it online... thanks.
You guys here are a great source for help.

[KuDaH]

Re: Vizio 32 inch (VA320M) Eco 1080p black screen

Took the main board off and there was another voltage regulator on the back side. Never saw it. I did some readings. Does this look ok?

U103 -> pcb designation
L101 -> line 1 of the IC
G9084-50 -> line 2 of the IC
pin 1 = 5.1 mv
pin 2 = 4.98 V
pin 3 = 9.06 V