Vizio VL370M Screen problem

[mu2]

Hi,

I have a Vizio VL370M with a screen issue. This problem occurred just after an intermittent power outage that also took out the cable box.
The screen looks similar to this photo in a recent post (https://www.badcaps.net/forum/showth...ghlight=vl370m) but jsog replaced the t-con without any change.
The t-con in the set is an LG 6870C-08247A and the main board is 3637-0552-0150 (5E).
I doubt that the panel is bad since the image changes if I change the menu or input. All the fuses and fl's on the t-con and main board are ok. The 1.8 volt regulator on the t-con is correct and all the voltage regulators on the main board are good. No bloated caps anywhere.
Has anyone seen this problem?
I hate to buy a main board first and then find out it's the t-con.

Thanks,
Mike

[retiredcaps]

Re: Vizio VL370M Screen problem

The 1.8 volt regulator on the t-con is correct and all the voltage regulators on the main board are good.

We have had 2 people in the last 3 months say that the voltage regulators were good only to find out they were wrong. I'm not saying you are wrong, but if you want us to verify, post your findings like so

U100 -> PCB designator
AL1117 -> part number
pin 1 = 2.0V
pin 2 = 3.25V
pin3 = 5.00V

PS. This is especially important with Vizios as many of them have problems with voltage regulators on the main board.

[selldoor]

Re: Vizio VL370M Screen problem

Remove clean and reseat ALL connectors.

Did you have a source connected when taking the pictures.

Is the sound ok?

[mu2]

Re: Vizio VL370M Screen problem

Update on the screen problem.
I hooked up an hdmi input and got sound and a very squashed picture - maybe 1/2" at the top. The longer the set was on it began to show a good image then fade to white.
Currently the set has been on for about 20 minutes and the picture has completely filled the screen and quality is great. Everything seems to be working. Menu, input selects, volume, etc.
I have to cycle the set on and off and see what happens.
Not quite sure what to think now - I don't know if it's a thermal problem or not.
Regarding the regulators. I'm pretty familiar with the 1117 regulators. I measured the two resistors and calculated the voltage output. My measurements confirmed the calculation.
I think the main board is used in 4 different Vizio models.

Thanks,
Mike

[mu2]

Re: Vizio VL370M Screen problem

Hi,
Here's the latest on the Vizio with the screen issue. I was able to get a manual with voltages for the main board. All voltages are correct and the t-con 1.8 volt fixed regulator is good. The blue led on the t-con board comes on initially and then goes out. Vizio logo changes to white and back lights come on normally.
I've heated the power supply board, t-con board and main board and I cannot change the following sequence. Cooling components also seems to have no effect. The following sequence is repeatable.
Once the set is on for about 13 minutes all is well.
When first turned on there is a blue 1/2" band of video at the top of the screen - shown in the photo t=0. The rest of the screen gradually gets brighter and brighter. At about 4 minutes the video band gets larger - as shown in t=4. Roughly 10 minutes after being turned on there is the "no signal" present with the bad band at the top of the screen (t=10). Finally, at t=13 all is well.
Everything works at this point, hdmi, tuner, menu, sound, etc.
It's hard for me to believe that the panel could be bad - but I'll leave it to the experts.
I think it's either t-con or main board and would welcome some opinions before I purchase a board.
Thanks
Mike

[selldoor]

Re: Vizio VL370M Screen problem

Did you clean and reseat all connectors on the Tcon? Also cant really tell from your picture but you have checked the fuse and voltage at the regulator, are there any voltage test points and is the board scattered with components marked flxx - if so these may be fusible links and should be tested as fuses?

[tom66]

Re: Vizio VL370M Screen problem

That looks a lot like a loose or intermittent LVDS cable problem.

[mu2]

Re: Vizio VL370M Screen problem

Hi,

I did clean and reseat the lvds cable but not the ribbon cables from the t-con to the display. I've tapped on various areas of the main and t-con boards and wiggled the lvds cable - doesn't seem to be intermittent.
Also checked the fuses and fusible links on both the t-con and main boards.
Thanks
Mike

[tom66]

Re: Vizio VL370M Screen problem

In which case I would consider the panel as being a possible fault. Seems more and more common nowadays.

[ben7]

Re: Vizio VL370M Screen problem

Hi,
Here's the latest on the Vizio with the screen issue. I was able to get a manual with voltages for the main board. All voltages are correct and the t-con 1.8 volt fixed regulator is good. The blue led on the t-con board comes on initially and then goes out. Vizio logo changes to white and back lights come on normally.
I've heated the power supply board, t-con board and main board and I cannot change the following sequence. Cooling components also seems to have no effect. The following sequence is repeatable.
Once the set is on for about 13 minutes all is well.
When first turned on there is a blue 1/2" band of video at the top of the screen - shown in the photo t=0. The rest of the screen gradually gets brighter and brighter. At about 4 minutes the video band gets larger - as shown in t=4. Roughly 10 minutes after being turned on there is the "no signal" present with the bad band at the top of the screen (t=10). Finally, at t=13 all is well.
Everything works at this point, hdmi, tuner, menu, sound, etc.
It's hard for me to believe that the panel could be bad - but I'll leave it to the experts.
I think it's either t-con or main board and would welcome some opinions before I purchase a board.
Thanks
Mike

Its very weird. But it kinda sounds like a bad capacitor somewhere, b/c you say that it gets better after a few minutes. I would check the voltage regulators on the mainboard, and t-con.

[kevinm34232]

Re: Vizio VL370M Screen problem

I had an LG with a similar problem, when first turned on picture would be good but then picture would freeze in "thirds" horizontally. It would stay frozen for awhile then after several minutes it would start working normally. Tried a new T-Con board same results. Sold the LCD panel to someone and they said it worked fine so concluded it was problem with video IC on main board.

Also had a Vizio with which displayed a white screen, new T-Con board same results and the voltage regulators tested good on the main board, guessing the same problem on that one.

[ben7]

Re: Vizio VL370M Screen problem

Actually, a nice way of figuring out which components could be bad is to turn the set on, and use a hairdryer to heat up areas of the board. Don't heat it up too hot, or some caps might explode. If you heat it up in one area, and the picture goes back to normal, then you know something in that area is bad!

[mu2]

Re: Vizio VL370M Screen problem

The video on the screen does freeze before it works normally. As time goes on the lower portion of the screen freezes then eventually all works. The sound is not affected during the warm up period.
I did use a hair dryer to try to narrow the problem to a board or area. Also tried cooling spray. Couldn't find a sensitive area on any of the boards.
The original owner said that the problem happened after a intermittent power outage. Her cable box died in the outage.

[ben7]

Re: Vizio VL370M Screen problem

The video on the screen does freeze before it works normally. As time goes on the lower portion of the screen freezes then eventually all works. The sound is not affected during the warm up period.
I did use a hair dryer to try to narrow the problem to a board or area. Also tried cooling spray. Couldn't find a sensitive area on any of the boards.
The original owner said that the problem happened after a intermittent power outage. Her cable box died in the outage.

Maybe you should try to replace the big fat capacitor in the power supply.

b/c you said her cable box died, most likely there was a power surge.

[kevinm34232]

Re: Vizio VL370M Screen problem

I actually tried freeze spray and hair dryer on mine, seemed to point to the tcon board but that wasn't it. I guess having an oscilloscope would help in this case see if waveforms going to tcon board?

[ben7]

Re: Vizio VL370M Screen problem

Both of you, try measuring the voltage on both of these capacitors. DC and AC too. If there is a lot of ripple on the capacitor(s) it will show up as AC.

[killian6pk]

Re: Vizio VL370M Screen problem

In the picture in Post 16 on the lower right side there is a silver box that the cable hooks into. Not sure what its name is, but I am wondering if that might be bad or causing some of these problems. I would not know how to go about testing it. It may be a crazy idea, but it is one of the few components on Vizio Boards that are the same across all models. My vizio has all the power rails working with correct voltages, my backlights work, but I can't get a picture on the set. Like I said might be a crazy idea.

[ben7]

Re: Vizio VL370M Screen problem

In the picture in Post 16 on the lower right side there is a silver box that the cable hooks into. Not sure what its name is, but I am wondering if that might be bad or causing some of these problems. I would not know how to go about testing it. It may be a crazy idea, but it is one of the few components on Vizio Boards that are the same across all models. My vizio has all the power rails working with correct voltages, my backlights work, but I can't get a picture on the set. Like I said might be a crazy idea.

Did you check the voltages on the capacitors?

Most people only check the voltage on the linear regulators, but if a capacitor fails on a switching regulator, it might go unnoticed. The capacitors I circled in red are situated next to a small chip, and a big inductor, which suggests a switching regulator.

If the regulator and caps are good, then you should check the eeprom's on the board.

[killian6pk]

Re: Vizio VL370M Screen problem

Did you check the voltages on the capacitors?

Most people only check the voltage on the linear regulators, but if a capacitor fails on a switching regulator, it might go unnoticed. The capacitors I circled in red are situated next to a small chip, and a big inductor, which suggests a switching regulator.

If the regulator and caps are good, then you should check the eeprom's on the board.

Thanks for the reply. My board is a a little different as it comes from a 32" model. But I will check my main board for those caps & voltages. What voltage should I expect to find?
My eeprom was replaced.
All the 1117 regulators were replaced. I don't want to hijack this thread as I have one started on my tv: Vizio E321VL If you don't mind I will post there, what I find.

[ben7]

Re: Vizio VL370M Screen problem

Thanks for the reply. My board is a a little different as it comes from a 32" model. But I will check my main board for those caps & voltages. What voltage should I expect to find?
My eeprom was replaced.
All the 1117 regulators were replaced. I don't want to hijack this thread as I have one started on my tv: Vizio E321VL If you don't mind I will post there, what I find.

Okey, here is the link for others.