Vizio E471VLE Dead

[Roush2fast]

Hello all and happy New Year, I recently acquired this TV from a friend who stated "it's dead". I have had some success in the past restoring so I figured I would give this a go. I'm not an experienced electrician but I am comfortable using a meter and repairing pcb's. My lack of experience translates into difficulty diagnosing which is why I'm here.

Upon attempted startup the set does nothing but a very short and very faint one time logo flash if even that. Preliminary testing yields the following results.

Power board fuse = good
No bloated or leaking caps
Main cap 168v

Pins with main board disconnected

1 - 5.2v = 5.3
2 - " "
3 - " "
4 - gnd
5 - " "
6 - " "
7 - " "
8 - 12v = 0
9 - 12v = 0
10 -12v = 0
11 - p on/off = 0
12 - blo/off = 0
13 - lamp status = 0
14 - dimming = 0

Main board connected yields
Pins 1 through 3 = voltage rapidly fluctuating from 0 to 2.3v
Pins 4 through 14 = 0

Can hear a small tick from power board every 1-2 seconds from area to the right of main cap

Please advise as to what I can do to determine if this is a power or main board problem. Thanks in advance

[dskall]

Re: Vizio E471VLE Dead

With main board disconnected you can jumper pin 1 to pin 11&12. You should then get your 12vdc and should get backlights. I suspect problem with main board if your standby voltage is fluctuating when connected. Check also your main cap when jumped. It should read around 390vdc

[Roush2fast]

Re: Vizio E471VLE Dead

With main board disconnected you can jumper pin 1 to pin 11&12. You should then get your 12vdc and should get backlights. I suspect problem with main board if your standby voltage is fluctuating when connected. Check also your main cap when jumped. It should read around 390vdc

Thanks for the reply. Can I jump without a resistor ?

[dskall]

Re: Vizio E471VLE Dead

You can use 600ohm to 1k

[Roush2fast]

Re: Vizio E471VLE Dead

You can use 600ohm to 1k

I'll have to dig one up. I'll get back to you in a little while after completing jump and test. Thanks again

[budm]

Re: Vizio E471VLE Dead

You can also try this:
Unplug the power to the power supply board, then use hair dryer to heat up the start-up/running caps C160, C161 for about a minute then power up the board with all the cables connected to see if the Standby Voltage will be steady or not.

Vizio/JVC 0500-0405-1340 Power Supply / Backlight Inverter

[Roush2fast]

Re: Vizio E471VLE Dead

you can also try this:
Unplug the power to the power supply board, then use hair dryer to heat up the start-up/running caps c160, c161 for about a minute then power up the board with all the cables connected to see if the standby voltage will be steady or not.

Vizio/jvc 0500-0405-1340 power supply / backlight inverter

10-4

[Roush2fast]

Re: Vizio E471VLE Dead

With main board disconnected you can jumper pin 1 to pin 11&12. You should then get your 12vdc and should get backlights. I suspect problem with main board if your standby voltage is fluctuating when connected. Check also your main cap when jumped. It should read around 390vdc

Ok jumped pins 1, 11, 12 and have backlights. At this point all voltages across cn201 are correct and stable. Main cap cap value is 383v.

Going to try Bud's suggestion real quick and will post results


Thanks again for assistance.

[Roush2fast]

Re: Vizio E471VLE Dead

You can also try this:
Unplug the power to the power supply board, then use hair dryer to heat up the start-up/running caps C160, C161 for about a minute then power up the board with all the cables connected to see if the Standby Voltage will be steady or not.

Vizio/JVC 0500-0405-1340 Power Supply / Backlight Inverter

Tested and results are the same. Voltages fluctuating rapidly 0-3v

[Roush2fast]

Re: Vizio E471VLE Dead

So where do I go from here ? Do these results indicate a main board failure ?

[dskall]

Re: Vizio E471VLE Dead

I would say you have bad regulator or something on main board loading down standby voltage

[Roush2fast]

Re: Vizio E471VLE Dead

I would say you have bad regulator or something on main board loading down standby voltage

I am having trouble finding the original and revised main board available for purchase. Is it feasible determine exactly what's malfunctioning on the board or is this a scrap ?

[budm]

Re: Vizio E471VLE Dead

Try disconnecting the IR board from the main board to see if the STBY will be steady.

[Roush2fast]

Re: Vizio E471VLE Dead

Try disconnecting the IR board from the main board to see if the STBY will be steady.

Will when I get back to the house. Thanks

[Roush2fast]

Re: Vizio E471VLE Dead

Try disconnecting the IR board from the main board to see if the STBY will be steady.

Same result. Does this pinpoint the main board as the issue ? Is there any way to determine what component on the board is failing ? Looks like servicing the board might be the only hope as I cannot find a replacement.

[budm]

Re: Vizio E471VLE Dead

At this point, something on the main board is drawing too much current so the STBY 5V goes into shutdown/restart cycle.
May be check the resistance between GND and the 5VSTBY pin with all the board connected to see if it may show really low resistance or not.

[Roush2fast]

Re: Vizio E471VLE Dead

At this point, something on the main board is drawing too much current so the STBY 5V goes into shutdown/restart cycle.
May be check the resistance between GND and the 5VSTBY pin with all the board connected to see if it may show really low resistance or not.

Ok I will check this in the morning. Thanks

[Roush2fast]

Re: Vizio E471VLE Dead

At this point, something on the main board is drawing too much current so the STBY 5V goes into shutdown/restart cycle.
May be check the resistance between GND and the 5VSTBY pin with all the board connected to see if it may show really low resistance or not.

I could not get an accurate reading. Resistance jumps from 1 to all over the place.

[dskall]

Re: Vizio E471VLE Dead

You are checking resistance with power off

[budm]

Re: Vizio E471VLE Dead

TV is unplugged from the AC outlet when checking the resistance.