Bad main board or power supply? Vizio E420-a0

[S.gilletly]

Hello Friends,
I have a Vizio E420-A0 and am trying to diagnose what the problem is. I'm getting no power and no sound. This is what voltage I get when I test the power supply.
CN201 with tv off
1. 5.3v stand by
2. 5.3v stand by
3,4,5 zero volts
6. 0.15v or 151mv
7. 0.15v or 151mv
8,9 zero volts
10.1.8v
11.1.8v
12. Zero
When I press the power button I get the same readings. In addition I tested CN301 and get zero volts on vout1&2 and on LED with tv off or on. I also checked where the power button is located and that is also getting voltage. My gut tells me its probably the power supply. I don't have much experience and want to avoid buying the wrong replacement part. Any help would be greatly appreciated.

[budm]

Re: Bad main board or power supply? Vizio E420-a0

1) We need pin names follow by the Voltage reading for each pin.Without the name those readings you report mean nothing.
2) We need good clear pictures of the boards and how all the boards are connected together.
3) We do not have the TV in front of us to look at so the more details you provide the more helps and correct information you will receive.

[S.gilletly]

Re: Bad main board or power supply? Vizio E420-a0

All right thank you. I'll post when I get home from work 👍

[S.gilletly]

Re: Bad main board or power supply? Vizio E420-a0

Okay I have attached pictures and here are the pins names with voltage.
CN301 both on and off
Led1 zero vdc
Vout1 zero vdc
Led2 zero vdc
Vout2 zero vdc

CN201 both on and off
5. 1vsb =5.3vdc
5. 1vsb=5.3vdc
Gnd = zero
Gnd = zero
Gnd = zero
12v = 0.15vdc
12v = 0.15vdc
Ps on/off = zero
Blu on/off= zero
Pwm 1 = 1.8vdc
Pwm 2= 1.8vdc
N.C = zero
Thanks for your help

[budm]

Re: Bad main board or power supply? Vizio E420-a0

Ps on/off = zero
Blu on/off= zero

The main board is not sending the PS-ON to turn on the rest of the power supply, it also does not send the BL-ON ti turn on the backlighst circuits.
Go to shopjimmy.com to see if there is EEPROM that will fix this symptom or not.

[S.gilletly]

Re: Bad main board or power supply? Vizio E420-a0

Will do thank you much budm. I will update after repair.

[CapLeaker]

Re: Bad main board or power supply? Vizio E420-a0

Have you tried freezing the EEPROM with a can of air upside down, then plug the tv in and turn it on?

[S.gilletly]

Have you tried freezing the EEPROM with a can of air upside down, then plug the tv in and turn it on?

No I have not tried that. I'm curious as to what that is supposed to do. Could you elaborate as to what it does to the EEPROM that would cause it to work. Also how long would it correct the issue if it did work?

[R_J]

Re: Bad main board or power supply? Vizio E420-a0

I can't say what actually happens inside the ic but I do know freezing it can work, I have read a faulty ic and when a varify was done it failed. After freezing the ic and reading the data it was slightly different.

[CapLeaker]

Re: Bad main board or power supply? Vizio E420-a0

I have about a 70% success rate with that trick. It doesn't work always. It seems that if you really cool (freeze) an EEPROM or an IC, that some can be made to work again for a short time.

[S.gilletly]

Re: Bad main board or power supply? Vizio E420-a0

Quick update I believe you were correct it was the EEPROM chip. TVs up and running !!!! Thank you all for your help. ��������

[S.gilletly]

Re: Bad main board or power supply? Vizio E420-a0

I replaced a prom by the way. I didn’t even try to freeze the old one