Vizio M320SR turns off after logo

[Roush2fast]

Re: Vizio M320SR turns off after logo

Does the large capacitor still have 389V DC when the set is squealing and are all the DC output supplies still operating and is there still 13.7V on the IC A6069H between pin 3 & 5.

If you disconnect the Inverter cable does the squealing stop.

Only thing that yields a result is disconnecting the main board when in stand by. The squeeling stops then once reconnected the Vizio lights blinks indicating reset and the squeeling returns when the blinking stops.

As far as your other questions yes everything seems to be performing optimally less the sound. l need the TV to fail again so I can test. I will run a load on it tomorrow and see how it goes.

[Roush2fast]

Re: Vizio M320SR turns off after logo

OK the TV failed again. I have tested everything but the backlight lead. I am a little confused how to test this with the way the connection is labeled. Do I test each lead connected then disconnected when powered on ? Also , do I just test each lead grounded to metal chassis or use one of the NC pins. Another question is why does led 5 have two leads while 1-4 have one? How do I test led 5 ?

[dick_barton]

Re: Vizio M320SR turns off after logo

So when it failed does the large capacitor still have 389V DC and is there still 13.7V on the IC A6069H between pin 3 & 5.?

[Roush2fast]

Re: Vizio M320SR turns off after logo

So when it failed does the large capacitor still have 389V DC and is there still 13.7V on the IC A6069H between pin 3 & 5.?

Yes to both

[dick_barton]

Re: Vizio M320SR turns off after logo

So when it fails you still have 398V DC across the cap, 13.7V between pins 3 & 5 of A6069H, normal sound, picture on screen when using a flashlight to view?

If so can you measure the voltage to chassis on all the pins of CN8501 connector at switch on. It should peak and then may drop very quickly.

[Roush2fast]

Re: Vizio M320SR turns off after logo

So when it fails you still have 398V DC across the cap, 13.7V between pins 3 & 5 of A6069H, normal sound, picture on screen when using a flashlight to view?

Triple confirmed 389v at cap , A6069H fluctuates 13.5 ~ 13.8 , Normal sound and visible picture with flashlight.

If so can you measure the voltage to chassis on all the pins of CN8501 connector at switch on. It should peak and then may drop very quickly.

CN8501 Test Results

LED 1 Peak 9.9v then drops to 0 when back lights turn off

LED 2 Peak 9.9v then drops to 0 when back lights turn off

LED 3 Peak 9.9v then drops to 0 when back lights turn off

LED 4 Peak 9.9v then drops to 0 when back lights turn off

Testing LED 5 yielded different results each time. Voltages were consistent on both LED 5 pins.

Test 1 Peak 93v then drops to 38v when back lights turn off
Test 2 Peak 89v then drops to 38v when back lights turn off
Test 3 Peak 91v then drops to 18v when back lights turn off

What do these results translate to ?

[Roush2fast]

Re: Vizio M320SR turns off after logo

Anything ?

[dick_barton]

Re: Vizio M320SR turns off after logo

Those readings suggest that you have a led problem or led problems. It could also be that the interconnections of the led strips behind the panel need to checked for poor connections.

Your next step is to look for Youtube video's on how to check the leds and led strip connections.

[vinceroger69]

Re: Vizio M320SR turns off after logo

this video may help you strip down the tv to the led strips
https://www.youtube.com/watch?v=NI9wOZKHOVE
and how to test the leds
https://www.youtube.com/watch?v=K_VfM4grw3I

once you get your set stripped down to the led strips post a picture and we should be able to show you the areas to bridge if you need to do it.

[Roush2fast]

Re: Vizio M320SR turns off after logo

I get the same voltages with the led connector unplugged. Wouldn't that suggest a problem with the board ?

Also , the TV works properly for a few days after leaving it unplugged for 24 hours. Is this consistent with bad LED's ? I would think they either work or do not. I just want to be sure before I go through this step.

Thanks for the help Barton and Vince.

[dick_barton]

Re: Vizio M320SR turns off after logo

So when it fails you still have 398V DC across the cap, 13.7V between pins 3 & 5 of A6069H, normal sound, picture on screen when using a flashlight to view?

Triple confirmed 389v at cap , A6069H fluctuates 13.5 ~ 13.8 , Normal sound and visible picture with flashlight.

I cannot guarantee that it is a led / led strip connection problem but all the symptoms you give above are leading me to that conclusion.

[vinceroger69]

Re: Vizio M320SR turns off after logo

intermittant faults are always hard to locate and find, at this point your ruling out possible causes as long as your really carefull with the lcd panel you should be fine but like any tv when disassembling any lcd panel theres a slight risk of damage happening.

[Roush2fast]

Re: Vizio M320SR turns off after logo

intermittant faults are always hard to locate and find, at this point your ruling out possible causes as long as your really carefull with the lcd panel you should be fine but like any tv when disassembling any lcd panel theres a slight risk of damage happening.

I am comfortable with this process so I might give it a go. Is it down to power board or LED strips ? I can get a new power board for $26 off EBAY so I am considering trying it. If it's the strips they run around $65 and at that point I would rather buy a new TV. Well checking the LED's doesn't cost anything so I might as well check. Will post back results.

Thanks again

[dick_barton]

Re: Vizio M320SR turns off after logo

You can wait and see what others may conclude before proceeding.

There are a lot of Youtube videos showing how to connect led strips together (bypassing any poor connections) by soldering wires across the connection points and also how to test leds using your multimeter.

[vinceroger69]

Re: Vizio M320SR turns off after logo

You can wait and see what others may conclude before proceeding.

There are a lot of Youtube videos showing how to connect led strips together (bypassing any poor connections) by soldering wires across the connection points and also how to test leds using your multimeter.

i was trying to find those videos and add links but could see any showing how to actually place the wire bridges but im on a small screen phone so its awkward to search on youtube etc.

[Roush2fast]

Re: Vizio M320SR turns off after logo

I will research and consider my options. Thanks again and I will post back results.

[dick_barton]

Re: Vizio M320SR turns off after logo

Testing leds
https://www.youtube.com/watch?v=K_VfM4grw3I

Diagnosing faulty led/connectors
https://www.youtube.com/watch?v=Bf5T2wwtydY

[Roush2fast]

Re: Vizio M320SR turns off after logo

Testing leds
https://www.youtube.com/watch?v=K_VfM4grw3I

Diagnosing faulty led/connectors
https://www.youtube.com/watch?v=Bf5T2wwtydY

Well thank you sir

[Roush2fast]

Re: Vizio M320SR turns off after logo

Well I was not expecting this configuration. The TV only has two strips at the top. All LEDs illuminate on power up. I tested the TV when it was working and all voltages were copacetic. In failure I have only 38v on led 5 pin and 0v on led 1-4 (cn8501). How do I test these strips and is it necessary seeing that all illuminate on boot before they shut off? Power board problem maybe ?

[dick_barton]

Re: Vizio M320SR turns off after logo

How long do the leds stay on for before going off. Can you turn the backlights all the way down so you can see if any one led is not illuminating.