M420VT will not Power on.. Solved Mainboard

[102mm]

I Just wanted to make this post since i couldn't find this model on the forum. hope this will help someone.

Model: M420VT
Main Board P/N:CBPFTQACB2K010

Symptom:Will not power on; 5VSB low only when attached to Mainboard; Vizio Logo goes from a dim white to brighter white then goes dim again.

Fault: Audio Amp IC (U602) P/N: STA339BW ($5ea @ UTSource.net)

I found out that this part was the problem when the board i purchased from ebay would power up, but had no sound. Upon inspecting the ebay board i noticed the audio amp was burned. I decided to pull the amp off my old board and install it on the new one and got the exact same symptoms.

Also... The vizio logo on this modelis white. it does not turn amber.

[jason123]

Re: M420VT will not Power on.. Solved Mainboard

I have the same model. M420VT works fine 90% of time.. occasionally (sometimes once a week, other times several times a night) it shuts off. I turn it back on, and back to normal. Audio does seem funky, but not bad.
When I contacted Vizio about this.. they wanted to troubleshoot.. so they asked me to do a "System Reset", going to "Help" reset and erase all settings. I attempted that, gives me a confirmation on the screen asking if I indeed want to erase it all.. I say yes.. nothing happens.. the windows goes away, the system goes on playing the current channel.. for that.. they say I need a technician.. Any suggestions?

[keeney123]

Re: M420VT will not Power on.. Solved Mainboard

On Vizo I remember if the remote control is not the original to the TV then it will not have a green color button which actually resets the TV. It has been a year since I repair a Vizo so it is an old memory.

[jason123]

Re: M420VT will not Power on.. Solved Mainboard

Does anyone have experience with the M420VT? An update to my earlier description, it doesn't seem to shut off, but the backlight turns off! Audio still keeps going. I shut it down, then turn back on, and it's happy again.

[colorvision]

Re: M420VT will not Power on.. Solved Mainboard

102mm - do you know if the TV will power up with the audio IC removed?

I have the exact same issue and would like to confirm before going to deap.

Thanks

[102mm]

Re: M420VT will not Power on.. Solved Mainboard

Yes, the set powered up when i removed the chip. It's still running fine today after replacing it.

[ivtec]

Re: M420VT will not Power on.. Solved Mainboard

Yes, the set powered up when i removed the chip. It's still running fine today after replacing it.

I would try to heat up the BGA chip with a heat blower,as this model is famous for main board cold solders on the BGA chip,