Vizio XVT3D650SV - Help

[newpey]

Re: Vizio XVT3D650SV - Help

The probe wires are soldered on to the meter. Battery is fine as well. If I am reading the pins correctly then they go like this..

back side
16, 14, 12, 10, 8, 6, 4, 2

front of plug that is facing me
15, 13, 11, 9, 7, 5, 3, 1

[bammbammfran]

Re: Vizio XVT3D650SV - Help

Well then back at it!

Tested the wires and pins from main board and on power board:
1 0
2 0
3 0
4 0
5 -5.18
6 -5.18
7 -5.18
8 -5.18
9 -5.18
10 -5.18
11 -5.18
12 -5.18
13 -5.14
14 -5.13
15 0
16 -5.13

5 volt fuse -5.13 on both sides
12 volt fuse 0.02 on one side and 0 on the other

On the 2 voltage regulators, regardless of how I ground the black probe, I see the same or very similar volts across the pins minus ground.

Well, I don't know how to say it but, this looks all wrong
1through4 should be +5
5-9 should be grounds
10-12 should be 12 but may show zero
and on the voltage regulators are you still saying that all the pins are showing 5 volts ??

are the batteries in your tester good ?
Maybe you have the red and black lead plugged into the tester backwards ?

what do the pins at the power supply show with the main board wire disconnected ?

[newpey]

Re: Vizio XVT3D650SV - Help

The regulator 7805 5V regulator is not going to show any input (12V) voltage because you do not have the 12V output from the power supply since the 12V/24V power supply is not working right now.
You should download that datasheet and look at the pinout of the 1117.

Gotcha. That makes sense

[newpey]

Re: Vizio XVT3D650SV - Help

What do you use for the black probe? Is the reading showing minus 5.23V (-5.23) reading?

"R310A: -5.17 on both sides" that will indicate open Base-Emitter junction of that transistor, unless I am wrong, the Emitter is connected to Ground from what I can see on the traces of the board.

Yes it shows minus.. I have the meter set to 20DCV I dont understand what that means as it is not possible to have negative volts?

I either put the black probe on pin 1 for ground or use the chassis.

[budm]

Re: Vizio XVT3D650SV - Help

OK, my board looks a little different from your picture. Please see picture

R310A: -5.17 on both sides

A: -5.23
B: -5.23
C: 0
D: 0

What do you use for the black probe? Is the reading showing minus 5.23V (-5.23) reading?

"R310A: -5.17 on both sides" that will indicate open Base-Emitter junction of that transistor, unless I am wrong, the Emitter is connected to Ground from what I can see on the traces of the board.

[budm]

Re: Vizio XVT3D650SV - Help

The regulator 7805 5V regulator is not going to show any input (12V) voltage because you do not have the 12V output from the power supply since the 12V/24V power supply is not working right now.
You should download that datasheet and look at the pinout of the 1117.

[newpey]

Re: Vizio XVT3D650SV - Help

Do Not get too excited yet ! That center pin is not supposed to reach the board like the other 2 pins do
So if you think that is what is wrong ?? Sorry !!

Well then back at it!

Tested the wires and pins from main board and on power board:
1 0
2 0
3 0
4 0
5 -5.18
6 -5.18
7 -5.18
8 -5.18
9 -5.18
10 -5.18
11 -5.18
12 -5.18
13 -5.14
14 -5.13
15 0
16 -5.13

5 volt fuse -5.13 on both sides
12 volt fuse 0.02 on one side and 0 on the other

On the 2 voltage regulators, regardless of how I ground the black probe, I see the same or very similar volts across the pins minus ground.

[bammbammfran]

Re: Vizio XVT3D650SV - Help

OK, I started testing away. THEN I noticed the ground pin is burned through on one of the voltage regulators on the main board when I was testing ohms

I am excited to see an actual issue!

Do Not get too excited yet ! That center pin is not supposed to reach the board like the other 2 pins do
So if you think that is what is wrong ?? Sorry !!

[newpey]

Re: Vizio XVT3D650SV - Help

I just read https://www.badcaps.net/forum/showthread.php?t=22231 Great thread! Now I understand how to test them.

How do I find the part number / replacement for the voltage regulator in question? I can't find that info anywhere

[newpey]

Re: Vizio XVT3D650SV - Help

OK, I started testing away. THEN I noticed the ground pin is burned through on one of the voltage regulators on the main board when I was testing ohms

I checked the fuses around it and they all seem to be working fine.

Writing on it is: 7805CG RKA07. Do I just order one and replace it? IS there an actual part number? Could anything else be messed up from this guy?

Also, I am really unsure how to test the voltage regulators correctly. If I use the ground wire from the 16 pin plug OR if I use the metal on the TV, my dcv appear to be about the same on all pins and tab. I would like to understand how to correctly test these.

I am excited to see an actual issue!

[newpey]

Re: Vizio XVT3D650SV - Help

OK, my board looks a little different from your picture. Please see picture

R310A: -5.17 on both sides

A: -5.23
B: -5.23
C: 0
D: 0

[bammbammfran]

Re: Vizio XVT3D650SV - Help

As I mentioned, your voltage regulators should have a ground pin so you should not get voltage on all 3 pins and of course they should not be almost the same voltage.
You can confirm the ground with an ohm meter.

on the voltage regulators
If you look at them with the largest tab to the left
On the 1117 adjustable smaller one top pin would be input, center pin and large tab would be output and the lower pin would be ground
On the larger one, the top pin would be output, the center pin and large tab would be Ground and the lower pin would be input

While you are retesting the 2 voltage regulators.
I would remove the wire from the pin 13 out of the 16 pin plug at the power board side and check that wire separately for voltage and then check the actual pin of the power supply too
To remove the wire, lift slightly on the white tab of the plug at that pin with something pointy and then slide the wire out

also check pin 1 on one of the larger connectors for voltage at dim-pwm-signal

[newpey]

Re: Vizio XVT3D650SV - Help

OK you guys officially have my head spinning. I need to go take some electrical engineering classes to fully understand what is being said above lol!!

Let me test the pins you want. I will also re-test the voltage regulators. I will make sure I use the ground wire/pin

[budm]

Re: Vizio XVT3D650SV - Help

OK, this is not going to be easy, you will have to get access to Q301 which is the transistor that receives the PS_ON signal fro pin 13, this signal is fed to R310A (1K) to the BASE of Q301. We need to find out what DC voltage we have at E and B, we know that one end of R310A that is connected to pin 13 of CN202 has 5VDC on it, so I expect to see about 0.6~0.8Vdc between E and B. Th hard will be that you will to work with the board powered up which can be dangerous.
Q301 when it is turned on by ps_on, it will then turn on Q302 which will turn on OPTO, then the Photo transistor inside the Opto is turn on which it then turn on the transistor to supply the B+ to run the PFC controller IC and the SMPS IC for the 12V/24V section.

[budm]

Re: Vizio XVT3D650SV - Help

I am not worried about that right now, it is the PFC circuits that have me concerned since it is not going up like it should, the PS_ON is also at 5V I expect it to be less than 5V due to the bias resistors and the Vbe junction voltage. I have a feeling the ps_on is not getting all the way to turn on the Transistor or the Opto. It is hard to trace out that REMOTE_ON/OFF line to see where it goes. I will have to zoom in more to see. My be you have better eyes than I do.

[bammbammfran]

Re: Vizio XVT3D650SV - Help

Thanks bud
Helps to have a good one shot picture to work with
I now see the 5-12-18 & 24 source transformers

Still, those two voltage regulator readings have me confused ?

[budm]

Re: Vizio XVT3D650SV - Help

The 12V and the 24V are generated by the same power transformer T601 and is turned on by the ps_on, the 5vsb and the switched 18V (also turn on by PS_ON) is generated by T901. The 12v/24v SMPS runs on boosted PFC voltage. Also see post 21.
His V readings do look right at all, not sure what he used for GND. REF.

[bammbammfran]

Re: Vizio XVT3D650SV - Help

OK I did some testing on the main board:

Voltage Regulator on bottom right (7806cg rka07):
Pins:
Top 5.17
Middle 5.18
Bottom 5.17
Out 5.18

Voltage Regulator on bottom left: (m462 g1117)
Pins:
Top 5.17
Middle 5.16
Bottom 5.17
Out 5.16
8

These do not look correct considering that the one tab should be a ground.
For instance: on the 7806 ? which I think is a 7805-- it should be the center small pin and the large tab

Are you sure you are using your tester correctly and using a proper ground ?

I have a feeling that the 12 volt supply where I pointed out that F1 fuse that looked questionable should be probably on at the same time as the 5 volts.
Can you post a bottom picture of the power supply board

[newpey]

Re: Vizio XVT3D650SV - Help

That worries me....

So the history of it...

It started to not turn on unless unplugged for hours (overnight) while trouble shooting it, I drained the 3 caps you had me test by shorting them (learned later there are better ways to drain them). This kept the TV turning on while I waited for new caps to come in for the power board as I thought one was swollen. At some point the TV never turned on again. I replaced those caps but still no luck. I figured I fried something somewhere. I ordered a brand new power board and installed it but same issue.

So now I am stuck with it busted and no clue what the issue is other than what you just said (which is more info than i had!)

Soooooo i prob caused it and at least i admitted it but still sucks!

[budm]

Re: Vizio XVT3D650SV - Help

OK, so the PS_ON (ON/OFF) control line is stuck on and you do not have PFC voltage function to run the 12V and 24V power supply and turn on the switched 18V power supply. Not good.
Did the problem just happen by itself or the TV was hit by any power surge, etc, or worked on by some one else before?