Vizio e550i-b2 won’t turn on, standby 4.97v

[Mmatt]

Working on a Vizio e550i-b2 tv that won't power on. I have 4.97v standby with or without the main board connected. Based on some (bad) research this led me to replace the main board. Still won't power on. I'm getting 0v at the smaller connector above the larger connector where I measured standby voltage. The smaller connector is marked 28v. Also, there is no white light coming on under the power button. I resoldered the connector between the power board and board next to it (led board I think it's called). This is my first attempt at television repair and would appreciate any help.

[dick_barton]

Re: Vizio e550i-b2 won't turn on, standby 4.97v

Some power supplies require 0V to bring them out of standby.With the mainboard disconnected use a 1K jumper resistor (or close to that value) connected from standby to ground and check what secondary supplies you have then.

[R_J]

Re: Vizio e550i-b2 won't turn on, standby 4.97v

If you want to check the power supply, disconnect the cable between the power supply and main board, then connect 5VSB to PS-ON, You can use around a 1k resistor

[Mmatt]

Re: Vizio e550i-b2 won't turn on, standby 4.97v

All I have is a 4.7k resistor. I’ll get a 1k tomorrow and check. Where am I checking for secondary supplies and what will I be looking for. Am I checking voltage at the 28v smaller connector above the large svsb connector? This is all new to me, but I’d like to learn.

[handsworth]

Re: Vizio e550i-b2 won't turn on, standby 4.97v

E550i-B2 has a common soldering fault between the led driver and the power supply connector. Remove both boards together. Disconnect them after removing. The solder joints on the bottom of the power supply of this connection may (probably) are old and loose. Resolder this connector. I have bought this model at least 10 times from people who said no power. At least 9 had the bad solder joints. Everyone fired right back up after the repair.

[Mmatt]

Re: Vizio e550i-b2 won't turn on, standby 4.97v

I had already resoldered and got nothing. Tonight I shorted between standby and ps on and got fluctuated voltage at the 28v connector. Checked continuity on all wires between psu and main board. All were good. Reconnected all connectors and tried to check voltage at power button. When I pressed power button the set came on. It is working fine now. I have no idea what the problem was, although I did put in a new main board. If anyone has an idea what fixed it, I would sure be interested to know.