Vizio E291-A1 No Power

[thrasherx]

Symptoms:
-No standby lights
-Power button works (verified voltage drop on the output of the board from 3V to lower)
-Mainline fuse near A/C inlet of power supply is good
-Power supply output voltages are as follows:
ON/OFF: 0V
DIM: 0.051V
+12V: 12.62V
+12V: 12.62V
GND: 0V
GND: 0V
GND: 0V
24V_B: 24.05V
24V_B: 24.05V
PS_ON: 4.69V
+5.2V: 5.164V
+5.2V: 5.164V

Main board model: 715G5661-M01-000-004K
Power supply model: 715G5721-P01-001-002M

I haven't been able to find schematics or the service manual.

Thanks!

[budm]

Re: Vizio E291-A1 No Power

http://www.shopjimmy.com/catalogsear...=Vizio+E291-A1
Your main board is not sending out the command signals.
BTW, are yo sure you do not have any DCV on the PS-ON pin? No PS-ON = No switched 12V/24V output but you are showing 12V/24V. Does PS-ON Voltage Toggle HIGH/LO?

[thrasherx]

Re: Vizio E291-A1 No Power

http://www.shopjimmy.com/catalogsear...=Vizio+E291-A1
Your main board is not sending out the command signals.

Thanks. I removed the EMI shield/heatsink and found a small piece of copper bridging two legs of the main processor. Is there more troubleshooting that can be done, or do I have to replace the main board?

I re-measured and modified the original post.

[budm]

Re: Vizio E291-A1 No Power

I do not have any info for the main board, lots of Vizio failed due to Voltage regulator or bad EEPROM.

[thrasherx]

Re: Vizio E291-A1 No Power

I do not have any info for the main board, lots of Vizio failed due to Voltage regulator or bad EEPROM.

I saw the symptoms of bad EEPROM and most of them still result in the standby light being on. Since I'm not getting any power at all, I figured it's more likely a voltage regulator.

Being somewhat inexperienced, I was hoping someone could point out components to check.

[thrasherx]

Re: Vizio E291-A1 No Power

What should the ON/OFF voltage be at the power supply? Can I manually apply a constant 3V to get the TV to turn on and bypass the main board? If so, will the video processor be off, thus no picture?

I'll probably just replace the main board.

[budm]

Re: Vizio E291-A1 No Power

That ON/OFF pin is for accepting Backlights ON (BL-ON, INVER-ON) command from the the main board.
For ACTIVE HIGH: <1VDC = OFF, >2VDC = ON, same for PS-ON signal.
To force on the power supply you must disconnect command signal wires going back to the main board first and then use the 1K resistors (1 per signal pin) between standby power supply pin and the command signal receiving pins on the power supply board.