Vizio M3D550SR won't turn on unless....

[DesertRat]

This has been an interesting project. It was given to me DOA with unknown problem. I've diagnosed it down to the dimmer and BL_On or the on/off. I've uploaded a picture of the main board with arrows to the parts I've replaced on the main board. The picture of the power supply is included for reference.

Here's what it's doing at this point since it's no longer DOA. I can do a continuity test to ground on the dimmer and BL-On connectors, and the TV will require a hard reset (holding power button down on TV for 30 seconds) to come on. When it comes on, you can do anything you want, it can be on for as long as you want. But when you turn it off, if you unplug it, you have to do the above mentioned hard reset to get it started again, after the continuity test each time.

That all makes no sense to me either. But I thought maybe someone had run across a similar problem. If so, can you point me in the next direction to look? The voltages on the three LDO's in the picture are within specs.

[DesertRat]

Re: Vizio M3D550SR won't turn on unless....

This is a picture of the TV working today. I left it unplugged overnight and I had to do the dimmer on/off drain mentioned above to get it going again this morning.

Another symptom I discovered last night is, when you turn the TV off the screen will go black, then after about a minute the screen lights up again, but with no picture or anything. When you hit the power button, the LED's dim down to almost out, and it sits there like that until you turn it back on. Almost like a sleep mode, instead of completely shutting down. Is this normal for this model?

[nomoresonys]

Re: Vizio M3D550SR won't turn on unless....

I think not, try a factory reset then a firmware update if the first doesn't work, might not fix it but it shouldn't hurt any.

[DesertRat]

Re: Vizio M3D550SR won't turn on unless....

Thanks nomoresonys, I did a factory reset, but haven't done a firmware update. That might do the trick. Thanks again!