vx37l no picture no sound

[eagle00799]

Hi everyone, a total rookie/newbie here. I plug in and have the amber light and when I turn on I get the white light but no sign of backlight and have to unplug to power down. Checking the power supply the fuse is good and I get the 24v,12v,5v and the A is 72.9, B is 19.6v on both rails. The On is 2.11 and Off is 16.3. I check U2 at 2.05,3.29,5.04. U7 at 23.8,1.11,3.29. U8 at 2.04,3.28,5.06. U33 at 2.05,3.29,5.04. Is the reading on U7 bad? Any suggestions? Also the 2 24v rails are the same but the plugs are different, 1 has 10 wires with the A and B empty and the other plug all 12 holes are occupied with 2 white wires going to the B pin. I might have gotten these 2 plugs mixed up and now am not sure which plug goes to which rail. Again any help would be greatly appreciated.

[budm]

Does you board look like this?
http://s807.photobucket.com/albums/y...37L%20HDTV10A/
Otherwise post the pictures of the boards using attachment upload.
Did you check the components on the two backlight inverter boards? Your 12/24/5v power supplies are wotking per your reading, so the problem can be the inverter boards, or it is not getting the Backlights on signal from the main board.
There are many voltage regulators on the main board that needs to be check also.
What is the P/N of U7?

[selldoor]

Welcome to the forum-

Without part numbers for each voltage regulator, we don't know for sure if they are the right output voltages. So list the part numbers. whitlst it takes more room it is easier to read if you put (as an example)

U2 ST1117 2.05,3.29,5.04.

U7 is 23.8 a typo? if not it does look bad.

Plugs: Just before we spend hours hunting this info can you check the plug & sockets are not labelled in some way.

It has happened before.


We can help a lot more if you please post good clear pictures of the whole chassis, and then pictures of each board, front and back and close up of connectors, (max resolution 2000x2000 and 2MB) using the manage attachments button, which is found by clicking "go advanced" under quick reply.

Please do not post inline and offsite as they slow down the loading of pages.

Examples of what is needed
http://www.badcaps.net/forum/attachm...1&d=1290283049

http://www.badcaps.net/forum/attachm...7&d=1280167246

It will be useful if you can say a bit about yourself - skills tools etc.

Have you been able to find a service manual for it?

[eagle00799]

I have the 1 inverted board on the left and the p/n on U7 is amc1117 f0734f and the 23.8 is correct and not a typo. Ok I can't figure out how to do pictures from my phone so I will have to get out the camera then put them on the laptop then go to the library to connect to the internet.

[eagle00799]

Ok here are some pics of what i am working with,sorry they are not the best but hope they will work.

[tibimakai]

Those pictures are not good at all. You should be able to read the part numbers from those pictures.

[eagle00799]

Your right Tibi and i will get a different camera and try again.

[selldoor]

Are all the regulators the same type. Do any of them state the voltage?

Data sheet attached

[budm]

From the voltage reading for the U2, U8, and U33 at pin 1 (ADJ) and pin2 (OUTPUT) we are seeing, I can tell that they are adjustable 1117 series regulator, you can tell because of the Vref voltage is working, the Vref is 1.25v, so you add the pin 1 voltage reading with 1.25Vref, then that number will be the output voltage if the IC is working properly.
Pin1 is the ADJ pin, it uses external resistor network to set the output voltage on pin2. If they are fixed output, pin 1 would be 0V since it will be connected to ground.

U2 at 2.05, 3.29, 5.04: 2.05 + 1.25= 3.3V (within 3%)

U7 at 23.8, 1.11, 3.29: This one we do not have the P/N, it does not look right.

U8 at 2.04, 3.28, 5.06: 2.04 + 1.25= 3.29V (within 3%)

U33 at 2.05,3.29,5.04: 2.05 + 1.25 = 3.3V (within 3%)

[cashkennedy]

The service manual on these includes a diagram for testing the DC DC regulators, and what voltages are acceptable.

From what i remember hte equivalent to U33 (the one that fails on the 32" models), is U32 / OR U3. (Its one of the 1117 regulators that fails)

Im quite certain you didnt test all the regulators on the board, as most of these have around 5-6 regulators to test.

http://elektrotanya.com/vizio_vx37l_.../download.html is a link to the manual, see pages 9-1 and 9-5.

[eagle00799]

I will have to get the pics tomorrow but these are the readings I have so far. U2-amc1117 f0734f is 2.05,3.29,5.04 U4-amc1117 f0734f is 2.03,3.27,5.4 U7-amc1117 f0734f is 23.8,1.11,3.29 U8- amc1117 f0734f is 2.04,3.28,5.06 U9-k1117s45 736 is 0.3,1.51,3.29 U33-amc1117 f0734f is 2.05,3.29,5.04 Only #9 is a different style.

[cashkennedy]

Based on the order your reading the voltages, you seem to be testing the ground pin / adj pin first. (Assuming obviously that you were consistent in how you measured them, by the way if your going counter clockwise around it (which it seems you are), then it goes top tab (output), first pin (ground/adj), middle pin (output), third pin (input). Once again that is for counter clockwise.

So for U7 you have some crazy crazy high ground voltage. Your problem is probably related to this. I think i heard one person claim these vizios sometimes have issue with the ground screws not connecting well, wouldnt hurt to try unscrewing cleaning and rescrewing all the board screws. Maybe check if you get continuity between that pin and the ground.

[selldoor]

its a small thing but its doing my head in - I have re formatted your post as I asked you to post it
I will have to get the pics tomorrow but these are the readings I have so far.
U2-amc1117 f0734f.. is 2.05,3.29,5.04
U4-amc1117 f0734f.. is 2.03,3.27,5.4
U7-amc1117 f0734f.. is 23.8,1.11,3.29
U8-amc1117 f0734f.. is 2.04,3.28,5.06
U9-k1117s45 736 .... is 0.30,1.51,3.29
U33-amc1117 f0734f is 2.05,3.29,5.04
Only #9 is a different style.

[eagle00799]

Sorry selldoor, i will get this right at some point. Hopefully before i drive everyone insane. I am trying to post pics but am having problems with a security token not being inplace. I will keep trying.

[budm]

U7 sure does not look right. I will look at my chassis to see what this IC is.

[selldoor]

Originally Posted by eagle00799

Sorry selldoor, i will get this right at some point. Hopefully before i drive everyone insane. I am trying to post pics but am having problems with a security token not being inplace. I will keep trying.

Hopefully it because they are too good

Its probably because they are too big file size. Having got good detailed pic you have to downsize them to less than 2mb and less than 2000x2000.
nothing to do with a security token

[eagle00799]

001.jpg

003.jpg

004.jpg

005.jpg

006.jpg

007.jpg

008.jpg

009.jpg

010.jpg

011.jpg

[eagle00799]

Sorry the first one's are running down the page but here are the pics.

[selldoor]

Good effort - I think I have cracked the easy bit with help from budm
http://i807.photobucket.com/albums/y...A/DSC02553.jpg
The top socket appears to have the additional white wires?

[selldoor]

While the set is in pieces I want you to test some parts on the inverter board. By each of the capacitors and one on its own there are fuses. Please test them using 200 ohms setting on your meter. post the result ( should be the same as touching the probes together.)

Next with meter set on 2000 ohms I want you to test accross
both ends of the eight inverter transformers.( i think it is across pins 1 and 8 and 4 and 5.Post results like this
T1 1-8 xxxohms 4-5 xxxohms
T2 1-8 xxxohms 4-5 etc etc etc

Also going back to fuses in pic 17 and 18 just above the left hand side of the bottom socket there is a fuse at F1 marked 3A please check that as above.

Ok - i see a torch in one pic - two simple tests - you say there is no backlight.
Next opportunity when it is all connected up - make sure the grounding is ok - you may have to add some extra ground wires or screw the boards firmly back in switch it on in a dark room to make sure there is absoluetely nothing flashes on the screen.
Next - with a source connected pc or dvd? check with your torch at different angles to see if there is any image at all on the dark screen.