Vizio SV422XVT blinking amber/white power light

[What?]

Good day, hope all are healthy and cozy. I could use some help with my malfunctioning Vizio with a blinking power light. I have narrowed the problem to the main board but not sure what to do next. I guess it would be good to start with what I have done.

Problem:
I have no image, no sound, blinking power light. (left it plugged in overnight and it was still blinking the following morning). I tried the Vizio recommendations (hold power button for 30 seconds, press reset button, check the outlet is live)

Power Board:
I am getting 5v only. I have unplugged all connectors between the power board and main board and hooked up a 1kOhm resistor from 5v to PWR-ON and I get the 18v. I also hooked up 5v to backlight and the backlights came on. Power board is working.

Main Board:
I replaced 2 bulging capacitors on the main board in the DC/DC converter on the main board.
I am getting 5v only at the connector J1 on the main board. The 3 fuses at J1 are good. I have checked the smd transistors and mosfets in the DC/DC converter and they seem ok (did not remove from board).
I did Budm's suggestion to apply heat to DC/DC converter with a hair dryer except I used a heat gun and the blinking power light went out and stayed out. I think I overdid it with the heat and damaged the U50 dual mosfet. I had a close replacement so I swapped it out which caused other problems but in the end I am back to the blinking power light.
I went through the DC/DC converter troublshooting Budm posted and the results are:
J1 Pin 10,11,12,13,14 display 5v
J1 Pin 1,2 display 0v (pin 17 displays 0v)
J6 Pin 1,2 dispaly 0v
U1 pin 5,6,7,8 display 3.3v
U5, U7 display 3.3 v U88, U89 display 0v
U50 Pin 1,2,3,4 display 5v Pin 5,6,7,8 display 0v
U71,U94 display 0v
J6 Pin 1,2 display 0v

Any help or suggestions would be greatly appreciated.

[What?]

Re: Vizio SV422XVT blinking amber/white power light

I was poking around with an ESR meter and discovered 3 tiny smd caps close to connector J1 that indicate they are open. Would 3 tiny smd caps keep the tv from working?

[What?]

Re: Vizio SV422XVT blinking amber/white power light

I think I am pretty much screwed on this one, the main board is not available anywhere, I can't locate a schematic, I have no idea what the ratings on these tiny caps are and if someone did have the board they are priced way too high.

[retrorepair]

Re: Vizio SV422XVT blinking amber/white power light

Hi,

"I replaced 2 bulging capacitors on the main board in the DC/DC converter on the main board."

So you replaced the 2 caps that where bulging. If i where you, i would change all electrolitic caps in that board.

[What?]

Re: Vizio SV422XVT blinking amber/white power light

Thanks for the response retro. I checked all the caps with an ESR meter, I am pretty confident they are ok. I think the 2 caps that were bulged was because I overheated them trying to see if heating the board would make something happen.

[What?]

Re: Vizio SV422XVT blinking amber/white power light

I tried to replace the teeny tiny capacitors with standard soldering equipment and buggered the board. The tv is too old to find parts for, just gonna hang it up and go home.

[nomoresonys]

Re: Vizio SV422XVT blinking amber/white power light

On those little caps that read off, remove from board and recheck IF they check bad off board and tested correctly then sure enough it's bad, youtube is your friend for testing tutes if needed.

[What?]

Re: Vizio SV422XVT blinking amber/white power light

Thanks Nomoresonys, I checked them off board and I got no reading at all on the ESR or on the multimeter for 3 of them and dead short for 2 of them. Thanks for your input.

[nomoresonys]

Re: Vizio SV422XVT blinking amber/white power light

Can you replace those with new or donors from a spare board? nothing else shorted or amiss that you can tell?