Re: Vizio SV470XVT1A LCD No Picture/No Backlight
I'm going to put in the replacement (unknown condition) main board that the seller provided with the TV on Friday. I will duplicate the tests to see if I get different results.
I am still puzzled why there is no backlight if it has the correct voltage (24v) being fed into it. What other circuits are used to operate the backlight? Is there a way to test the other circuits causing the backlight failure.
tlm387
Member
Last Activity: 06-29-2016, 06:42 PM
Joined: 03-09-2011
Location:
-
Re: Vizio SV470XVT1A LCD No Picture/No Backlight
The identification numbers of the 6 voltage regulators are as follows:
There are 3: (circled in red)
1804
0809BL
The voltages are:
Vi to ground
1. 2.73v
2. 3.91v
3. 2.75v
Vo/Tab to ground
1. 1.250
2. 1.251
3. 1.248
(I can not find a datasheet for these)
There are 2: (circled in blue)
AZ7805T - E1
820J71
The datasheet specifies that these are 5.0 V output
They both measure from Vin to Vout 11.75v to 5.1v
...Leave a comment:
-
Re: Vizio SV470XVT1A LCD No Picture/No Backlight
My apologies for being a novice, but some of these voltage regulators have 3 pins connected and others only have 2 pins connected.
The ones that have 3 are labeled In Ground Out
The ones that have 2 are labeled Ground VO VI with the center pin VO disconnected.
In the picture you can see the center pin of one LDO is not connected. How do I test the ones with only 2 pins?...Leave a comment:
-
Re: Vizio SV470XVT1A LCD No Picture/No Backlight
Here are the pictures
I really appreciate any and all advice. Can anybody figure out why the TV would automatically go from standby to on by itself after being plugged in. That really does not make sense to me.
Also why would the power button only work sometimes and only once or twice at a time?
I do not have a service manual for this TV but I am fairly certain that the main logic processor is on the main board. If it is being under powered that might explain the unresponsive buttons....Leave a comment:
-
Re: Vizio SV470XVT1A LCD No Picture/No Backlight
Pictures are on the way, just as soon as the camera battery charges.
The voltage coming out of the power supply and into the main board is 11.75v. The power button works sometimes, but not consistently at all. And if it does work it only works one time.
The TV came with a replacement main board that was purchased online, I dont have any way of knowing if the replacement board is in working order but the TV exhibits the exact same symptoms with either board installed. I suppose there is a chance that...Leave a comment:
-
Re: Vizio SV470XVT1A LCD No Picture/No Backlight
The voltage going into the main board is less than 12 volts. Could the low voltage cause these problems?
On my main board U33 looks like an IC with 8 pins. Which pins should I test and what should the voltage be?Last edited by tlm387; 06-27-2011, 04:18 PM.Leave a comment:
-
Vizio SV470XVT1A LCD No Picture/No Backlight
I snagged a 47in Vizio LCD that is not working from Craigslist. I have very little background information about why/when it failed and what it did.
When I got it home and plugged it in the power supply clicked once and the amber VIZIO light lit up and then turned WHITE without me pressing ANY buttons. Upon it turning white (powering itself on?) it did not make any other clicks from the PSU.
I could hear the very faint/normal speaker pop. There is no backlight, no picture, and the side panel buttons are completely unresponsive. I have to unplug it to turn it off. ... -
Re: Samsung LN-S4692D Left Side Blur
I pulled the tv all the way apart today and exposed the tab bonds. I tried the trick of applying pressure to the tab bonds, but was unable to get the picture to change at all. I imagine that because the image did not change than all the tab bonds are ok.
I think I am going to source a replacement t-con for this tv first.Leave a comment:
-
Re: Samsung LN-S4692D Left Side Blur
Whoops my mistake, the problem actually occurs on the right side of the screenLeave a comment:
-
Samsung LN-S4692D Left Side Blur
Hey all
I've got another 46 inch puzzle here. This one is a Samsung LN-S4692D. I was told that "when you turn it on no picture is visible. The sound is there and you can cycle through the channels but can't see anything".
However when I got it home it had a picture
However it's not perfect, the left side of the screen is darker with a red hue, and has a lag or blur effect. The images seems to stay on the screen longer than they should. Occasionally there a vertical lines on the far right side of the screen, they tend to appear only if there is a ticker...
Last edited by tlm387; 03-23-2011, 12:09 PM. -
Re: Sony Bravia no Picture
Actually the old t-con board turned out to be fine I'm am running the original. My best guess was a bad fuse from the manufacturer, or a perhaps a power surge at some point in time.Leave a comment:
-
Re: Sony Bravia no Picture
Great Idea!
I am measuring ~.653 DC Amps with the LCD on and a movie playing, and the meter wired in circuit. Now thats less than the 5 AMP rating so all should be well right? Does that sound like a normal reading?
To me that does not sound like enough AMPS to power the entire t-con and LCD panel, but don't really have a working knowledge of electricity so I could be wrong here.
And I assume I measure this on DC current and not AC. Is this correct?
Thanks again for all your i...Leave a comment:
-
Re: Sony Bravia no Picture
Yeah I want to test the current load at that point, but it is on the underside of the main board and will be very difficult to measure with everything plugged in.
I only bridged the fuse so that I could see if that fuse was the issue. I have only tested the tv once and I am not leaving it plugged in unattended. So until the new main board comes in I will not be enjoying this tv.Leave a comment:
-
Re: Sony Bravia no Picture
Well I could be wrong here, but the t-con has a 3A fuse (not sure of it's voltage), which is less than the 5A fuse on the main board. So if the panel or t-con itself was drawing too much current than theoretically should't the 3A fuse blow first?...Leave a comment:
-
Re: Sony Bravia no Picture
I GOT THE SUCKER WORKING!!!!
Apparently I did I bad job on my jumper solder job, when i did it I just did a visual inspection to see that I had bridged blown fuse, being the size of a small bread crumb I should have tested for continuity.
(Among other potential problems)
So going back over the schematics I re tested all the fuses on the main (input) board. There are a 6 fuses listed on the schematics. There is a fuse called F1422 (5A 24V) which powers the TPC8109(TE12L) chip. This chip then runs out to the display....Last edited by tlm387; 03-18-2011, 01:43 AM.Leave a comment:
-
Re: Sony Bravia no Picture
Yeah I spent some time testing the fuses that I could find. I found a 5A 24V micro fuse type 1608 (Sony part #1-576-933-21) that I just could not get continuity from so I thought I found the problem. I jumped the fuse with a dab of solder, but all that happened was a rely clicking on and off until the standby light flashed a main board error.
So i un-soldered the jumper and the tv went back to behaving as it did in my first post.
For the record I have checked the fuse on the t-con and its appears to be fine. ...Last edited by tlm387; 03-17-2011, 11:27 PM.Leave a comment:
-
Re: Sony Bravia no Picture
Just to be certain, does anybody know how much voltage I should expect to see going into the t-con?Leave a comment:
-
Re: Sony Bravia no Picture
UPDATE:
I just found the service manual for this model. And the schematics were helpful. I am a novice at all this so I am probably missing a lot of important details provided by the schematics. I found something important.
I am getting just shy of 12vDC on each of the three 12v leads going into the input board. I suspect this means the power supply is functioning properly.Leave a comment:
-
Re: Sony Bravia no Picture
Ok well I found a pin on the t-con labeled "IN" and it runs straight into one side of the 3A pico fuse. So I took a voltage reading at that point and im only getting .16 volts.
Based on this I'm assuming that the tcon is not getting enough juice to function. So I figure it must be something wrong with the BU input board, or the power supply. Would this be a valid/accurate assumption?
Is there a sure fire way to tell if the power supply is putting out enough voltage to the input board? Where should I test and how much...Last edited by tlm387; 03-15-2011, 10:33 PM.Leave a comment:
-
Re: Sony Bravia no Picture
The LVDS cable runs from the t-con to the main input board. When testing voltage on the LVDS cable where should I place the negative lead of the multimeter?
I get the feeling that there is no power going to the t-con because the tv behaves the same with or without a t-con plugged in.Leave a comment:
No activity results to display
Leave a comment: