Vizio VS420LF1A Screen/backlight goes off after awhile

[Blackwolf]

I have a Vizio VS420LF1A that i had previously posted about here in this forum.
The back light and lcd was not coming on at all, yet the Vizio logo at the bottom was turning white. After testing several components i just gave up and purchased a new (used) PSU off ebay. I connected it and the TV worked great for 2 months or so. Unfortunately now Im having a problem where the tv will come on and work fine, but then the back light and lcd will just turn off (vizio logo still white) sometimes after several hours of use, or sometimes after just a few min. If i turn off the tv and let it sit for a few min after this happens, it will work for awhile, sometimes hours, sometimes just mins. Yesterday, the tv was on for several hours and worked perfectly, then towards the end of the night, it started doing it again. Im a bit puzzled as to why sometimes it works fine, then other times it exhibits this issue. I checked for obvious stuff like blown/bulging caps on the psu, but all looks well. I have pics that i took previously for the other thread available here

[tom66]

Re: Vizio VS420LF1A Screen/backlight goes off after awhile

Try unplugging the button panel on the TV.

[Blackwolf]

Re: Vizio VS420LF1A Screen/backlight goes off after awhile

Ok i will try that, but would that cause the backlight/lcd to turn off but leaving the vizio logo white? (not orange like when its in standby)

[tom66]

Re: Vizio VS420LF1A Screen/backlight goes off after awhile

Ok i will try that, but would that cause the backlight/lcd to turn off but leaving the vizio logo white? (not orange like when its in standby)

Probably not - although maybe if the button gets stuck the TV does odd things like that?

[selldoor]

Re: Vizio VS420LF1A Screen/backlight goes off after awhile

Does the sound stay on? Have you checked to see if there is still a very dark picture on the screen when it appears to have gone off - try with a flashlight at different angles.

[Blackwolf]

Re: Vizio VS420LF1A Screen/backlight goes off after awhile

The sound does stay on, and i do see the picture on the LCD when i look closely at it with a flash light, so it must be the back light. I turned it on today and it stayed on for several hours with out going out but then it happened. Is it bad inverter or psu issue perhaps? Why does it sometimes work for hours then other times only a few min? Maybe theres a short or something?

[selldoor]

Re: Vizio VS420LF1A Screen/backlight goes off after awhile

Please post clear pictures without flash of the inverter board and Tcon.

[Blackwolf]

Re: Vizio VS420LF1A Screen/backlight goes off after awhile

Some pics i took before are available here
https://www.badcaps.net/forum/showpo...33&postcount=3

These are the only 2 boards i see, is there another i may be missing somewhere?

[killian6pk]

Re: Vizio VS420LF1A Screen/backlight goes off after awhile

There should be one and possibly two inverter boards probably under a metal cover one on each side of the tv. All of the backlight wires will be plugged into them.

[killian6pk]

Re: Vizio VS420LF1A Screen/backlight goes off after awhile

disregard my previous message looks like your backlights are run off the power board so you want have any inverter boards. Not sure how that is being done though with just two connectors.