Vizio VO37L power problem

[ronm6962]

Re: Vizio VO37L power problem

So, while waiting for our time differences (EDT/PDT) to catch up, here's a recap of the problem and some additional testing for your consideration. When I plug in the TV, there is a click from the PSB, and the Vizio light on front is amber. Then when I press the Power button, another click is hear from the PSB, the Vizio light turns white, and the backlights come on. I think this is all normal at this point. Now the screen is lighted with a blue/gray tint, but no evidence of any video. No response from the Menu or Input buttons.

Wondering about your comment re the T-Con board, I decide to disconnect one of the ribbon cables that go from the board to the screen somewhere underneath the cabinet. Here is the results.....
Both cables connected give the lighted blue/gray screen as noted above.
CN6 disconnected gives a lighted blue/gray screen on the left, and a bright all white lighted screen on the right....half and half.
CN4 disconnected gives a lighted blue/gray screen on the right, and a bright all white lighted screen on the left....half and half.
Both CN4 and CN6 cables disconnected gives the same lighted blue/gray screen as with both cables connected. (I would have expected to see the whole screen white here, based on above.)???

So, does any of that help determine the functioning of the T-Con board?

[budm]

Re: Vizio VO37L power problem

Blue screen means when cable connected and gray when cable disconnected, that means the blue on the screen came form the main board to drive the panel, and grey when the T-CON is not getting the power (cable disconnected) is normal.
So I at this point there are two possibility, but at this point it is pointing to the main board. Where does this main board come from, EBAY? But I sure like to try new T-CON also. You will need an Oscilloscope to really verify if all the signals are present at the LDVS cable.

[ronm6962]

Re: Vizio VO37L power problem

OK, I need help understanding your last post. "Blue screen means when cable connected and gray when cable disconnected" I don't really get a "blue" screen anytime. I get the bluish gray (dim lit) screen or the bright white screen, as noted in my last post.

I don't have an oscilloscope or the knowledge to use one. Is there no other way to determine if the T-Con board is working?

[budm]

Re: Vizio VO37L power problem

OK, if you disconnect the cable to the T-CON, then you should see just light grey glow of the screen (similar to this but not as bright as shown here: http://s807.photobucket.com/user/bud...ml?sort=3&o=27), when you connect the cable back in and see color on the screen, that means the T-CON/Main board is doing something.
We can check the Voltage at the test points and the 3-pin regulators on the T-CON to see if they are present or not.

[ronm6962]

Re: Vizio VO37L power problem

Ok, that helps...thanks. When I disconnect the ribbon cables (CN4 and CN6) one at a time, I get half screen dim blue and half screen bright white (as in your picture). When I disconnect them both, I get the whole screen dim blue, same as when they are both connected. I will now try disconnecting the wired cable between the Main Board and the TCon Board and see what I get.

[ronm6962]

Re: Vizio VO37L power problem

So, when I disconnect the wired cable going into the T-Con Board, there is no change in the display....backlights on, dim blue/gray screen. Should there be a difference here?

[budm]

Re: Vizio VO37L power problem

Yes, so it looks like the the TC-ON is dead, or main board LVDS signals are dead.
Let take the voltage readings on the T-Con board test points next.
Take really good pictures of the board.

[ronm6962]

Re: Vizio VO37L power problem

Is this picture good enough for your purpose? I tried several settings and this was best of the lot. Also, what points on the board should I be probing for voltage? In a previous post we tested the only fuse I could find (F1) and it showed 12v.

[ronm6962]

Re: Vizio VO37L power problem

Here are some voltage readings from around the board. Label on the left is what was on the board, voltage reading on the right.
EXTVBR 0v
UBROUT 0v
DACOUT 3v
UCC 3.3v
1.8v 1.8v
2vs 1.6v
VGL -5v
VGH 20.9v
VDO 16v
SOE .2v
POL 1.6v
GSP 0v
GSC 1.8v
GOE .4v
US2 (voltage regulator) left to right 0v, 1.8v, 3.3v
Pin2 of CN1 connector reads 12v

[budm]

Re: Vizio VO37L power problem

I believe VGL should be in the -10V range, I will have to let TOM66 gives you the info on that.

[ronm6962]

Re: Vizio VO37L power problem

OK, thanks. Should I contact him, or did you do that?

[budm]

Re: Vizio VO37L power problem

He does not do PM, so hopefully he will see this thread.

[ronm6962]

Re: Vizio VO37L power problem

Oh, OK. I haven't seen him in this thread. Does that mean you are signing off?

[ronm6962]

Re: Vizio VO37L power problem

budm....just need to know if you are finished with this thread, so I can seek other help. I do appreciate all your help thus far. Thanks.

[vinceroger69]

Re: Vizio VO37L power problem

from a post from tom
T-con points AVDD, VGH, VGL, etc. (AVDD=14~18V, VGH=20~30V, VGL=-5~-10V)

[ronm6962]

Re: Vizio VO37L power problem

vinceroger69....thanks for your input on my problem. It appears the voltages I have (listed below) are OK based on your input above.
EXTVBR 0v
UBROUT 0v
DACOUT 3v
UCC 3.3v
1.8v 1.8v
2vs 1.6v
VGL -5v
VGH 20.9v
VDO 16v
SOE .2v
POL 1.6v
GSP 0v
GSC 1.8v
GOE .4v
US2 (voltage regulator) left to right 0v, 1.8v, 3.3v
Pin2 of CN1 connector reads 12v
One thing I'm still a bit confused about is the result of my diagnosis in Post 61. Given I get a dim blue/grey screen whether of not I have the LVDS cable connected or not, makes wonder about the T-con board. Any thoughts on that? Thanks.

[vinceroger69]

Re: Vizio VO37L power problem

I have only fixed a handfull of lcds too be honest and still learning so im not sure im sure budm or tom will be along to advise more.

[ronm6962]

Re: Vizio VO37L power problem

OK, thanks. I too am learning from this forum, and appreciate the willing nature of you folks to share your knowledge. I probably should have junked this TV a week ago, but it has become a challenge I really would like to resolve. (-:

[ronm6962]

Re: Vizio VO37L power problem

Ugh!! I ordered a replacement T-con board and installed it, in hopes that was the problem. Unfortunately, I get the same results. So now I have replaced all 4 boards (PS, Main, T-Con, and Inverter) with supposedly good working boards, and still get no video.

One last question before I throw in the towel.....should I get a Menu on the screen, (by pressing the menu button) without any input cables connected? Or put another way, what should a working screen look like when powered up and no input cables connected?

[tom66]

Re: Vizio VO37L power problem

To your second question, yes, you should.