Vizio SV420M Yellow Logo and That's All She Wrote!

[KookieProfessor]

Sorry, meant to say Orange Logo, Not Yellow!

I'm trying to diagnose the subject unit and have read all the available posts on this same unit with similar issues. I think it may be the EEPROM on the main logic board, but I'd like to be a bit more sure that I'm barking up the right tree.

I have 5.21 VSB at the power supply board
0V on PS_ON
PS_On wire disconnected at logic board and then when forcing the Pwr Supply on w/5VSB jumped to PS_ON through a 1Kohm resistor, I get 2.96V @ PS_ON, and 12 volts at the 12 V pins, but nothing else on any of the other power supply pins, nor any change using either the ON/Off button or the remote. (Just a constant standby as long as it's plugged into mains power.)

Fuse on Pwr Supply board is good of course, and both smd fuses on main board are good.

Checked the following as well on main board:

U2
In: 5.16V
Out: 3.34
Adj: 2.09

U3
Gnd: 2.03
V Out: 3.27
V In: 5.12

U4
V In: 3.27
V Out: 1.25
Adj: 0.00

U5
V In: 5.12
V Out: 3.30
Gnd: 2.06

U6
V In: 12.26
V Out: 8.17
Adj: 6.92

U7
V In: 5.12
V Out: 3.34
Adj: 2.09

U8
V In: 12.26
Gnd: 0.00
V Out: 5.05

Power Button :0.0V

Any further guidance/suggestions on further testing procedures would be greatly appreciated.

Thanks!

[budm]

Re: Vizio SV420M Yellow Logo and That's All She Wrote!

Can we see the pictures of the whole backside of the TV showing all the boards?
Also the pictures of the button board and also clarify the "Power Button :0.0V"

Notes from Shopjimmy regarding to the EEPROM:
IMPORTANT:
These main boards can have multiple failures, in addition to the EEPROM.
If EEPROM replacement does not repair your board, there are likely additional problems.

Symptoms EEPROM replacement CAN fix:
- Display is frozen on VIZIO logo screen*
- TV won't power on with remote/buttons when plugged-in (VIZIO is lit in orange, but won't turn to white)
- TV turns on when first plugged-in, but it won't turn back on after 30 minutes of being off
- TV shuts off and goes back to standby mode (orange VIZIO lit) after you turn it on

Symptoms EEPROM replacement CAN NOT Fix:
- TV turns on but has NO backlight
- TV turns on AND backlights are on, but has no video display at all
- HDMI issues
- Audio issues

[nomoresonys]

Re: Vizio SV420M Yellow Logo and That's All She Wrote!

Try cooling or heating that eeprom with a hairdryer, see if tv starts up if only for a while.

[KookieProfessor]

Re: Vizio SV420M Yellow Logo and That's All She Wrote!

Thanks Guys!

Couple of things:

1) This is the exact fault, per the Shopjimmy notes:
"TV won't power on with remote/buttons when plugged-in (VIZIO is lit in orange, but won't turn to white)"

2) I rechecked the On/Off switch (the top button of the row of buttons on the right side of the main logic board as viewed from the back of the TV), and got 2.39V at the top hot pin, and 2.31V at the bottom pin when pressing the button, 0.0V off the button. This was while having the jumper in place from 5VSB to the PS_ON pin with the black wire from PS_ON pulled from the Logic board connector.

I've also attached some pics, and will try heating/cooling the EEPROM, hopefully later today.

As far as I understand, the voltage checks I did on all the components previously mentioned prove all those things out, correct?

[R_J]

Re: Vizio SV420M Yellow Logo and That's All She Wrote!

When you freeze the eeprom the tv must be unplugged from ac.
Unplug the tv, freeze the eeprom ic, then wait a few seconds for the ic to freeze, Then plug the tv in and try turning on. You may need to try this more than once.

[nomoresonys]

Re: Vizio SV420M Yellow Logo and That's All She Wrote!

OR pop the board in the freezer for 30 minutes.

[KookieProfessor]

Re: Vizio SV420M Yellow Logo and That's All She Wrote!

I will try the freezer trick a bit later today, thanks!

In the meantime, I did some more homework, so to speak.

I initially missed it, but U9 measures:

In: 3.3v
Out: 1.8v
Gnd: 0.55

so that looks good, correct?

Also, I've attached a pic of all the readings from the Pwr Supply connectors.

I'm not sure I understand the CN202 connections, which thus far all stay at 0v. I'm thinking that based upon CN201 supplying PS_ON to the main board, it should then return an Inverter_On signal to CN202, correct?

Not sure about these pins on CN202:
ACD?
DCR?

Thanks again for all the great insight! I'm learning!

[R_J]

Re: Vizio SV420M Yellow Logo and That's All She Wrote!

The pins on CN202 control the backlight, ON/OFF_INVERTER turns the backlight on and off. DIM controls the brightness of the backlight. LAMP_STATUS tells the main board if the backlight is on or off. The other pins like VBRA,ACD,DCR are not used on this model.
CN201 does not SUPPLY PS_ON to the main board, it is the control line FROM the main board to turn the power supply ON

[KookieProfessor]

Re: Vizio SV420M Yellow Logo and That's All She Wrote!

R_J,

Thanks for mentioning that. I did understand it that way, but got turned around when I wrote the question.

So to clarify further,

• the 5.1VSB from the Pwr Supply board is supplied to the Main board, and

• once the PS_ON signal is sent back to the Pwr Supply board from the Main Board (by activating the On/Off switch or the remote),

• this is the input to the Pwr Supply board to wake up and produce the 12V output, which then is also sent to the Main board, correct?

I suspect that the Mainboard will then signal the Pwr Supply to turn on the backlight by sending a signal to ON/OFF_Inverter, correct?

To prove out the backlight, can I jump 5VSB to the ON/OFF Inverter pin at CN202, through the 1K resistor like I did to get 12V out at CN201?

[nomoresonys]

Re: Vizio SV420M Yellow Logo and That's All She Wrote!

Make sure the cable from powerboard to mainboard is unhooked, when you try it you will need your first jumper in place then your on/off inverter to 5vsb probably also need one from dim to 5vsb, so 3 resistors.

[KookieProfessor]

Re: Vizio SV420M Yellow Logo and That's All She Wrote!

I threw the main board in the freezer for a few hours, and no change. .......

[KookieProfessor]

Re: Vizio SV420M Yellow Logo and That's All She Wrote!

nomoresonys,

Unhook both cables (CN201 & CN202) from the Pwr Supply board to the mainboard?

[nomoresonys]

Re: Vizio SV420M Yellow Logo and That's All She Wrote!

nomoresonys,

Unhook both cables (CN201 & CN202) from the Pwr Supply board to the mainboard?

Yes unhook both, you are self testing the powerboard and backlights.

[KookieProfessor]

Re: Vizio SV420M Yellow Logo and That's All She Wrote!

nomoresonys,

The picture I uploaded at 11:25am shows those measurements at the power supply board connectors.

[KookieProfessor]

Re: Vizio SV420M Yellow Logo and That's All She Wrote!

Sorry, make that 1:25pm

[nomoresonys]

Re: Vizio SV420M Yellow Logo and That's All She Wrote!

Right, the test in post #10 will supply the 5v to inverter on/off to see if the backlights come on and stay on, may need a resistor jumper on dim to 5vsb too.

[KookieProfessor]

Re: Vizio SV420M Yellow Logo and That's All She Wrote!

nomoresonys, R_L, budm,

So jumping 5VSB through a 1K resistor to the ON/OFF Inverter pin in addition to the PS_ON pin lit the backlight up just fine. I did have the harness from the Power Supply board disconnected from the Mainboard, so I assume that's why the orange Vizio Logo was not on. (Previously just plugging in the set illuminates it orange indicating 5VSB is good.)

At this point, knowing that the backlights work and both the 5VSB and the 12V signals from the Pwr Supply board are there, can I assume the Pwr Supply is good? (Should I load the 12 output to make sure it doesn't crash, or does verifying the backlight prove out the 12V rail is good, in and of itself?)

I'm thinking that with all the previous measurements made on the main board regulators, that I can be pretty sure now that it is the U14 EEPROM?

Is this a good assumption, or is there more I can do to rule anything else out?

Thanks Again!

[budm]

Re: Vizio SV420M Yellow Logo and That's All She Wrote!

Power supply board is fine, try new EEPROM, just make sure to get the right one for your main board.

[KookieProfessor]

Re: Vizio SV420M Yellow Logo and That's All She Wrote!

Awesome! Will order one up and report back once it's installed. ........

[KookieProfessor]

Re: Vizio SV420M Yellow Logo and That's All She Wrote!

Well,

I got the EEPROM from ShopJimmy, and finally installed it tonight .......... and no difference. I'm bummed. Any suggestions?

Seeing as though the backlight worked when I forced it on with a resistor from 5VSB, I'm guessing it's the main processor chip on the mainboard, but that's just a guess.

Not knowing enough about proper diagnostics, would that make sense with all the readings I took of the regulators on the mainboard?

Anyone have a mainboard available, if that's the next logical step?