My 3 year old Vizio M65 would not power on. No standby light or any indication that I was pressing the power button.
After trying the obvious solutions like making sure the wall plug had power I started advanced troubleshooting.
I took the back of the TV off and checked the fuse. You can’t tell if it is good by visually inspecting it. You have to do an ohm test with a multi-meter. If the fuse is blown you should not get a reading at all. If it is good you will get the same reading as crossing the leads. Fuse tested good.
I applied power and the first thing I noticed was a small flashing blue/purple LED on the back on the main board (the board with the HDMI connectors and such). I spent a good amount of time trying to research what that blinking light meant with no result. (Spoiler, the little LED is supposed to be solid red when the TV is in standby)
I read in some eBay part descriptions that the 12v power connectors on the main p/s were supposed to read 19v at standby (meaning all power supply connectors are unplugged). Using my multi-meter set on 200 DCV I found that the voltage was fluctuating between 18.8v and 19.1v. Not that far off, could be normal (it wasn’t normal). Next step was to measure the voltage under load (connectors plugged in). Under load the 12v pins should read 12v. In my case the voltage was fluctuating wildly from 0v to 9v. Smoking gun indicator of a bad power supply board. NOTE: When testing be sure not to accidentally hit one of the GROUND pins.
I ordered a new power supply board from eBay. 715G6887-P02-001-002 was printed on the board and actual part number on the sticker was ADTVE1835AC8.
IMPORTANT: not all Vizio M65 tvs use the same parts! Make sure the part number matches EXACTLY.
The new power supply measured a solid 19.1v at standby, no fluctuations at all. The mystery LED on the back of the main board was blue for about a second then turned solid red and stayed red. I assume now that the blue/purple flashing indicated a power issue. My TV is now working again!
I had a lot of trouble finding good troubleshooting info for this tv, so I hope this is helpful for someone. Please leave a comment if this helped keep your TV out of the landfill 🙂