Vizio VO370M LCD Orange Light Only

[BradBerger]

Hey everyone, new to the forum and having an issue with my Vizio TV.

It's a 42" VO370M model and was given to me by a friend that did not want to fix it. The orange Vizio light would come on, but nothing happened when pressing the power button.

I let it sit for a few months without touching it and decided one day to mess around with it. Miraculously, it powered on perfectly and I've been using it without issue for about a month or two. Well, my luck ran out last night when I went to turn it on and the original problem came back, orange standby light only.

Currently, I have the back taken off and have checked all connections without any success. I have a multimeter handy so I can check what I need. This seems like a common problem with Vizios so hopefully someone can lend some advice!

Thanks again everyone!

[Glitcher]

Re: Vizio VO370M LCD Orange Light Only

I would check the voltage regulators on the main board.

[BradBerger]

Re: Vizio VO370M LCD Orange Light Only

I should mention I am in no way an electronics expert so I may need a bit of an explanation of certain things.

[budm]

Re: Vizio VO370M LCD Orange Light Only

Yes, check the regulator's voltages, also check the fuses on the main board for < 1 Ohm and the voltage readings on both ends of the fuses with ref. to the chassis ground.
http://s807.photobucket.com/user/bud...?sort=3&page=1
Also check the voltage on the output pins of the power supply connectors.

[BradBerger]

Re: Vizio VO370M LCD Orange Light Only

Thanks for the quick responses. Here's what I have gathered so far...

U2
1117
pin 1 = 2.038V
pin 2 = 3.283V
pin 3 = 5.01V

U4
1117
pin 1 = 2.054V
pin 2 = 3.302V
pin 3 = 5.05V

U5
1117
pin 1 = 1.380V
pin 2 = 2.631V
pin 3 = 5.02V

U7
L391
G1084
pin 1 = 2.031V
pin 2 = 3.263V
pin 3 = 5.04V

U8
1117
pin 1 = 0.9mV
pin 2 = 1.248V
pin 3 = 3.254V

U11
7805CT
RAD947 G
pin 1 = 58mV
pin 2 = 0.7mV
pin 3 = 0.7mV

U9
1117
pin 1 = 1.252V
pin 2 = 2.488V
pin 3 = 5.04V

F1 read 0 Ohms but 102 Ohms when I switched the test leads.
F2 read 0 Ohms either way.

F1 voltage 5.04V on both ends
F2 voltage 59.6mV on both ends

Voltage output from power supply on 12V pins all 60.6mV
Voltage output from power supply on ST/+5V pins all 5.04V

Hope this helps!

[budm]

Re: Vizio VO370M LCD Orange Light Only

OK, the 12v will not be at the fuse until the main board sends the PS_ON signal to turn on the power supply board, so the U11 will not be putting out 5V since there is no 12v feeding it.
Otherwise all other regulators are putting out correct voltages (voltage between pin1 and pin 2 should always be 1.25v +/-2%).
So at this point, the main board is not sending out the PS_ON or the power supply is bad, you need to check the voltage at the ps_on pin on the power supply board to verify.

[BradBerger]

Re: Vizio VO370M LCD Orange Light Only

The voltage at the On/Off pin on the power supply is 5.8mV

So is that a sign that the power supply is bad?

[budm]

Re: Vizio VO370M LCD Orange Light Only

I need to see your board, I believe that ON/OFF pin is for the Backlights ON/OFF, there should be a pin with PS_ON (or STBY) on the power supply board. The main board is the one that generates all those signals and sends then to the power supply board.

[BradBerger]

Re: Vizio VO370M LCD Orange Light Only

Snapped a pic for you....I went ahead and tested INV_ON just in case that was it and it came to 13.7mV

[budm]

Re: Vizio VO370M LCD Orange Light Only

Well, the main board is not sending the Inverter on signal or the power supply on signal, so the main board is the problem.

[BradBerger]

Re: Vizio VO370M LCD Orange Light Only

I dont need to be pressing the Power button as I'm testing these do I?

Which pin do you think the PS_ON is, or is it even worth testing it?

If the main board is the problem, would it be easier to just replace it or try to locate the issue?

[budm]

Re: Vizio VO370M LCD Orange Light Only

You do need to hit the power button so the main board will send out the signals to the power supply board, I thought that is what you have done.
ON/OFF is the PS_ON.

[BradBerger]

Re: Vizio VO370M LCD Orange Light Only

Sorry about that, like I said not exactly an expert.

Anyway, went back and tested PS_ON and INV_ON again pressing the power button with no difference at all.

[budm]

Re: Vizio VO370M LCD Orange Light Only

OK, that confirm the main board is not working properly. The main board for this model is not cheap, I fixed the one in my pictures by using the main board from the VL370M, the bad main board that I have has problem with the main micro controller, it runs real hot in a few minutes and blow the fuse for the 5V.

[BradBerger]

Re: Vizio VO370M LCD Orange Light Only

So is there anything I can do to avoid replacing the entire board?

[budm]

Re: Vizio VO370M LCD Orange Light Only

I did not have any luck locating the problem, most Vizio main board failed due to bad regulator, but yours are OK. The price of the main board should come down when the holiday season ended, I would not spend more than $50 on the main board, also prepare for the power supply-inverter board to fail in the future.

[BradBerger]

Re: Vizio VO370M LCD Orange Light Only

Darn, looks like that's my only option. Thanks so much for your great help and information!

[BradBerger]

Re: Vizio VO370M LCD Orange Light Only

Bit of an update here.

I ordered a replacement main board and just installed it with no luck. Only this time, the white Vizio light comes on as well as the backlight. Then it sits there. No Input screen or anything, just backlight. I have a question about the part numbers on these boards. The original board in the TV was labeled 3637-0502-0150(0H) while the board I received has the part number 3637-0502-0150(0I). Does this different designation in the parentheses make all the difference? Or is something else causing the problem now?

[budm]

Re: Vizio VO370M LCD Orange Light Only

Just to be sure, re-seat the ribbon cable between the main board and the T-CON, if still no pictures then you need to check the DC voltage on the fuse in the T-CON board.

[BradBerger]

Re: Vizio VO370M LCD Orange Light Only

No voltage at all at the fuse on the T-CON board. I checked it with both main boards just in case. Nothing. What should I be looking for next?