Old Vizio E470VA, new problem

[EMD_Driver]

Hello everyone,

I did a job for someone and she gave me a Vizio E470VA. She said lightning had struck and the TV no longer worked. Before throwing it away, I decided to test it and see what I could find.

When the set is plugged in, the word Vizio below the screen lights up. It will then go off again. I can turn the set on with the remote, but I can see the entire screen flashing. It will go light and immediately dark. The flashing is very rhythmic and alternates about every second. I did an extensive search and could find no similar conditions. Also, while the screen is flashing, the Vizio logo below the screen does a very similar type of alternating between light and dim.

I pulled the PSU and tested it today. I got proper voltage on each of the pins, but they fluctuated a bit. I also noticed a faint clicking around the lower corner of the board. That clicking has the exact same rhythm as the flashing I described before. I'm attaching two pics of the board, in the hopes that someone might be able to help me figure out where the clicking is coming from and whether I should replace the entire board. If I can replace a component, I would rather do that.

Thanks!
Gary

Edit: I also uploaded a pic of the sticker on the board. The center pic is of the corner of the board where the faint clicking is coming from.

[budm]

Re: Old Vizio E470VA, new problem

https://www.badcaps.net/forum/attach...2&d=1503435331
We need to know what the DCV for all those pins of the two white connectors on the left side of the board. Make sure to put down the pin name first and follow by the Voltage reading for each pin, take the two sets of readings: one set when the TV is plugged in another set when the power switch is activated.

[EMD_Driver]

Re: Old Vizio E470VA, new problem

I'll be happy to get those measurements for you tomorrow.

One question..

Would I get the voltages you need with the PSU out of the set and the PSON jumpered to one of the 5v terminals, or should the readings be taken with everything hooked up?

Gary

[williej]

Re: Old Vizio E470VA, new problem

Test it out of the set,5vsb to pson and read the voltage.

[attainteddragon]

Re: Old Vizio E470VA, new problem

you need everything hooked up as normal. we need to see if you have command signals.

[EMD_Driver]

Re: Old Vizio E470VA, new problem

I took the measurements both ways. With the PSU installed and on the bench, with the PS_ON jumpered. For the purpose of this post, I flipped the image and cropped it to highlight the connectors.

The upper connector is labeled: CN903
I will list the pins and the voltages obtained beside each one, while the board is installed and the power on.

24v - 24.32-24.34v fluctuating.
24v - 24.32v
24v - 24.32v
24v - 24.32v
24v - 24.32v
Gnd
Gnd
Gnd
Gnd
Gnd
ENAELE - Unused
On/Off - 0.11v
Din - 3.37v

The lower connector is labeled CN905.
Same as above.. Board installed, power on.

On/Off - 0v
Dim - 0v
12v - 11.89v
12v - 11.89v
Gnd
Gnd
Gnd
24v - 24.32v
24v - 24.33v
PS_ON - 4.75v
5v - 5.2v
5v - 5.2v

With the board on the bench, I got the following voltages:

Connector CN903

24v - 23.02-24.03v
24v - 23.61-24.03v
24v - 23.51-24.06v
24v - 23.8-24.02v
24v - 23.4 - 24.03v
Gnd
Gnd
Gnd
Gnd
Gnd
ENAELE - Unused
On/Off - 0v
Dim - 0v

Connector CN905:

On/off - 0v
Dim - 0v
12v - 12.02-12.04v
12v - 12.02-12.08v
Gnd
Gnd
Gnd
24v - 23.8-24.09v
24v - 23.4-24.02v
PS_ON - 0v
5v - 5.2v
5v - 5.2v

With the board on the bench, the fluctuating voltages corresponded to the clicking heard on the board. Could this be due to the lack of a load? If these voltages all look good, should I suspect the inverter, or the main board next?

Thanks for the help!
Gary

[EMD_Driver]

Re: Old Vizio E470VA, new problem

I made a little 5 second video of what the TV is doing when powered on. Perhaps this will explain it a bit better than I could.

Gary

[budm]

Re: Old Vizio E470VA, new problem

On/Off - 0.11v
Din - 3.37v

Those two above signals are from the main board, they are fed into one connector and out to another connector to go the Inverter board.
Right now you do not have ON/OFF (BL-ON) signal from the main board to turn on the backlights circuit. You should verify that DIM signal again because you do have 3.37V on the input connector but not at the output connector that goes to the inverter board. You have problem on the main board some where, you can start by checking the Voltages of the Regulator ICs first.

[maxvalutech]

Re: Old Vizio E470VA, new problem

I have a couple of sets not same but similar make and note that at turn on the backlights come on bright then dim right down until picture time. Perhaps your set caught in this early bright/dim loop.

[EMD_Driver]

Re: Old Vizio E470VA, new problem

On/Off - 0.11v
Din - 3.37v

Those two above signals are from the main board, they are fed into one connector and out to another connector to go the Inverter board.
Right now you do not have ON/OFF (BL-ON) signal from the main board to turn on the backlights circuit. You should verify that DIM signal again because you do have 3.37V on the input connector but not at the output connector that goes to the inverter board. You have problem on the main board some where, you can start by checking the Voltages of the Regulator ICs first.

Thanks for the tip! I'll get those ICs checked and report back!

Gary

[EMD_Driver]

Re: Old Vizio E470VA, new problem

I finally got to test the voltages on the ICs and here's what I got.. I checked each terminal twice, to be sure. I also attached two pictures of the ICs in question. I only found four on the board.

U103
M271
G9084
3.80
5.04
9.57

U608
17089
06 11
11.87
0.7
9.02

U704
M272
1117-18
0.8
1.794
3.301

U706M-153
1117-33
0.8
3.3
5.14

Hopefully, one of you guys will be able to decode all this and help me out.

Thanks for looking!
Gary

[Th3_uN1Qu3]

Re: Old Vizio E470VA, new problem

Readings on U704 and U706M look fine. Unsure on the other two, i'm too sleepy and inebriated to look them up, wait for assistance from other members

[EMD_Driver]

Re: Old Vizio E470VA, new problem

Guess I didn't hit enter hard enough..

U706M-153
1117-33
0.8
3.3
5.14

Should read:

U706
M-153
1117-33
0.8
3.3
5.14

[attainteddragon]

Re: Old Vizio E470VA, new problem

i don't know what u608 is, but all of the other ldo's are good.

[EMD_Driver]

Re: Old Vizio E470VA, new problem

i don't know what u608 is, but all of the other ldo's are good.

Sorry about that..

U608 is a 17809

[attainteddragon]

Re: Old Vizio E470VA, new problem

found the data sheet, and the output is good.

[EMD_Driver]

Re: Old Vizio E470VA, new problem

found the data sheet, and the output is good.

So if all four mainboard ICs are showing good, where should I look next? What would cause the On/Off of CN903 to read 0.11v?

Thanks,
Gary

[attainteddragon]

Re: Old Vizio E470VA, new problem

it could be a bad cap, bad solder joint under the bga processor, or potentially any other surface mounted device.

you know for sure that you have a main board issue, so you can replace it, or you could trace back from the bl/on signal pin and try to find what may of failed. main boards are not easy.