Vizio E371VL won't turn over-orange Vizio only

[tibimakai]

I have this TV which won't turn on, only the Vizio logo turns orange.
I have reheated the U48 IC and replaced U18 and it still won't turn on.
There is only the 5V standby voltage.
I'm not sure, how to turn on this TV without the mainboard connected.
I have tried to jump the standby with the power on, but nothing happens, I'm only getting the 12V at the connector. No backlight at all.
I still have to remove the PS and measure the main caps, I didn't have time today.
Any input would be appreciated.
I have repaired before one of these TVs, but that one had the U18 problem only and by replacing it, it worked as it should. No luck now.
One more thing, which I'm confused about what could that be.
When I was reheating the U48 IC, at one point it appeared a solder blab on the right side of the IC. I'm thinking, that I may have blown out the solder from underneath of this IC?
First my question is, how to forcefully turn on the PS?

[tibimakai]

Re: Vizio E371VL won't turn over-orange Vizio only

On the connector, I have a VBR_B, Status, On/Off, 12V, GND and 5.1VSB.
What could be the VBR_B?
http://www.shopjimmy.com/vizio-0500-...pply-board.htm

[tom66]

Re: Vizio E371VL won't turn over-orange Vizio only

That's the brightness command for the backlight. To turn the backlight on, you need to connect ON/OFF to 5V. Use a 100 ohm resistor in series with that to protect against excessive current.

[tibimakai]

Re: Vizio E371VL won't turn over-orange Vizio only

I have used a 2.2k resistor, but the back light did not turn on.

[tibimakai]

Re: Vizio E371VL won't turn over-orange Vizio only

The 400V comes up for a second, then drops.
It could be inverter transformers or tubes?

[budm]

Re: Vizio E371VL won't turn over-orange Vizio only

I see VBR_B, STATUS, ON/OFF, and ???/OFF. I cannot clearly read the label.
There should be ON/OFF control (PS_ON) to turn on the power supply which will turn on the PFC Voltage booster circuit so the DC Voltage on the two main filer caps should jump from 165~170VDC to around 400VDC as long as the PS_ON is present, then there should be backlights ON/OFF (BL_ON) signal to turn on the backlights.
So if you do not have 400VDC then the backlights inverter circuit will not work until it has enough voltage (400VDC) to run.
You need to feed 3vdc to both of those xxx/off pins and see if 400VDC will be there and stay there and if the backlights will flash on at least.
You need to verify boosted voltage first before going further.

[budm]

Re: Vizio E371VL won't turn over-orange Vizio only

OK, I look at the bottom side of the board: http://www.shopjimmy.com/vizio-0500-...ply-board.htm#

The pin in question is labeled as 'REMOTE ON/OFF' which is the same as PS_ON. So you need to feed 3VDC to this pin and the 'INV ON/OFF' pin as printed on the bottom side of the board to get the PFC and the inverter to start.
This board is cheap.

[tibimakai]

Re: Vizio E371VL won't turn over-orange Vizio only

Thanks Bud. I know usually how it has to be done, but this one is different and I don't know how to command the inverter to turn on.
When I jump 5.1V to On/Off, it turns on the PS for a second, I see the 400V for that second.
That pin is again the same thing On/Off, not sure why it has double On/Off pins.
It would be the VBR_B line, that commands the inverter to turn on?

[budm]

Re: Vizio E371VL won't turn over-orange Vizio only

If you look at the bottom side of the board, it is labeled with better descriptions.
The label on the top side for the 'ON/OFF' is for the BL_ON, the other one 'P? ON/OFF' is the PS_ON.
Look at the bottom side of the board. You always need two signals and sometime the Dimmer signal also.
So when you hit the power switch, those two signals should be >2.5VDC and stay there until the TV is turned off.

Bottom line is, PS_ON and BL_ON must be present, then if the power supply has PFC Voltage booster, then that circuit must be functioning first before going further to inverter section.

[tibimakai]

Re: Vizio E371VL won't turn over-orange Vizio only

I will look for that, now it's to late.
Right now, I'm trying to turn on only the PS+inverter, to make sure that it's working first.

[budm]

Re: Vizio E371VL won't turn over-orange Vizio only

Yes, and Check those two signals on those two pins first so you will at least know if the main board is sending the correct signals or not first. I am going to bed too, it is getting late.

[tibimakai]

Re: Vizio E371VL won't turn over-orange Vizio only

You were right about the On/Off pins. I thought that they are the same, but they are not.
I have managed to turn on the back light.
So I have a mainboard problem.
I have replaced the EEPROM already and it did not change anything.
What else can I check?
Power on signal is not there. It is around 0.6V only, it's not always the same.

[budm]

Re: Vizio E371VL won't turn over-orange Vizio only

I have never do anything more than changing fuses and voltage regulators to fix the main board problem in Vizio. So I really do not have much suggestion.