Hello everyone,
I am currently trying to troubleshoot a 55 Vizio LED tv and need some guidance as I feel that I am out of my league on this one. I've scoured the threads trying to find my exact problem, but have been unsuccessful thus far.
The Symptoms:
1. Most importantly, the LED backlighting will not turn on, but the audio works just fine.
2. Upon plugging into the receptacle, the VIZIO emblem flashes Amber/White for approximately 1 minute or so, then ends on Amber (may be irrelevant, but wanted to throw in, just in case).
3. TV can be turned on via remote or control panel, all buttons seem to work fine, just can't see anything.
4. One last thing, it seems that after an extended period of time, the TV will shut off on its own.
My troubleshooting attempt:
The first thing i did was take the back panel off the TV and put power to it in order to check if the LED backlights attempted to come on, even if just briefly. Every start-up yielded the same results, no signs of light, not even a flicker. I checked both from the front of the TV and the pinholes from the backside of the panel and saw nothing.
Next, I did the flashlight test to see if there was an image on the screen. Lo and behold, I could see the video playing, just extremely faint. So at this point, I've got audio and image, just no backlighting.
Here's where i decided to start checking voltages on the Power Supply. My PS has 5V, 12V, 18V, and 24V. All of the voltages were fine, except there was practically 0V on the 24V output...which runs directly to the LED Driver Board (I've seen it called LED Driver Board and Backlight Inverter Board, not sure what the correct terminology is to be honest, I apologize if incorrect). This led me to believe that my LED Driver Board just wasn't receiving the 24V input it required to power the LEDs. Easy fix I thought, just focus on the PS.
Next, I combed over the PS searching for blown capacitors, burn marks, anything, but everything looked good visibly. Just to double check that the culprit was the PS, I wanted to try and isolate it from the circuit as best i could and re-check the voltages. I unplugged the LED Driver Board and checked my PS voltages and my 24V output was back from the dead, and all other voltage outputs were good as well. Therefore, at this stage I believed that my power supply was not the problem, but the LED Driver Board. When i reconnected the LED Driver Board, the 24V output on PS disappeared. Disconnected from LED Driver Board, it reappeared, which is a bit baffling, to me anyways. Maybe the LED board is malfunctioning and a feedback loop isn't allowing it to turn on for safety reasons? Just a shot in the dark?
Another thing that i noticed that has me intrigued is the "on/off" voltage that is supposed to turn on the LED Driver (I believe) seems to be dropping in voltage when the LED Driver Board is connected to the PS. With the PS isolated, the "on/off" output reads 3.3V, but as soon as I plug the LED Driver back in, the "on/off" outputs drops to 1.2V(along with losing the 24V as previously stated). This makes me think that the LED Driver board isn't receiving the proper voltage to tell it to turn on, which would make sense due to the fact that I haven't seen any spark of life on that board as of yet.
That brings us to now. I'm not sure how to determine where my problem lies...in the LED Driver Board or possibly my MB or PS not telling it to turn on. I would like to troubleshoot and fix this at the component level if possible. I'm no EE, but have always enjoyed dabbling in electric circuitshttps://www.badcaps.net/forum/images/smilies/icon_smile.gif.
Any guidance, ideas, or constructive criticism would be greatly appreciated.
If I need to post pics of the Boards or P/N's just let me know.
Thanks fellas
I am currently trying to troubleshoot a 55 Vizio LED tv and need some guidance as I feel that I am out of my league on this one. I've scoured the threads trying to find my exact problem, but have been unsuccessful thus far.
The Symptoms:
1. Most importantly, the LED backlighting will not turn on, but the audio works just fine.
2. Upon plugging into the receptacle, the VIZIO emblem flashes Amber/White for approximately 1 minute or so, then ends on Amber (may be irrelevant, but wanted to throw in, just in case).
3. TV can be turned on via remote or control panel, all buttons seem to work fine, just can't see anything.
4. One last thing, it seems that after an extended period of time, the TV will shut off on its own.
My troubleshooting attempt:
The first thing i did was take the back panel off the TV and put power to it in order to check if the LED backlights attempted to come on, even if just briefly. Every start-up yielded the same results, no signs of light, not even a flicker. I checked both from the front of the TV and the pinholes from the backside of the panel and saw nothing.
Next, I did the flashlight test to see if there was an image on the screen. Lo and behold, I could see the video playing, just extremely faint. So at this point, I've got audio and image, just no backlighting.
Here's where i decided to start checking voltages on the Power Supply. My PS has 5V, 12V, 18V, and 24V. All of the voltages were fine, except there was practically 0V on the 24V output...which runs directly to the LED Driver Board (I've seen it called LED Driver Board and Backlight Inverter Board, not sure what the correct terminology is to be honest, I apologize if incorrect). This led me to believe that my LED Driver Board just wasn't receiving the 24V input it required to power the LEDs. Easy fix I thought, just focus on the PS.
Next, I combed over the PS searching for blown capacitors, burn marks, anything, but everything looked good visibly. Just to double check that the culprit was the PS, I wanted to try and isolate it from the circuit as best i could and re-check the voltages. I unplugged the LED Driver Board and checked my PS voltages and my 24V output was back from the dead, and all other voltage outputs were good as well. Therefore, at this stage I believed that my power supply was not the problem, but the LED Driver Board. When i reconnected the LED Driver Board, the 24V output on PS disappeared. Disconnected from LED Driver Board, it reappeared, which is a bit baffling, to me anyways. Maybe the LED board is malfunctioning and a feedback loop isn't allowing it to turn on for safety reasons? Just a shot in the dark?
Another thing that i noticed that has me intrigued is the "on/off" voltage that is supposed to turn on the LED Driver (I believe) seems to be dropping in voltage when the LED Driver Board is connected to the PS. With the PS isolated, the "on/off" output reads 3.3V, but as soon as I plug the LED Driver back in, the "on/off" outputs drops to 1.2V(along with losing the 24V as previously stated). This makes me think that the LED Driver board isn't receiving the proper voltage to tell it to turn on, which would make sense due to the fact that I haven't seen any spark of life on that board as of yet.
That brings us to now. I'm not sure how to determine where my problem lies...in the LED Driver Board or possibly my MB or PS not telling it to turn on. I would like to troubleshoot and fix this at the component level if possible. I'm no EE, but have always enjoyed dabbling in electric circuitshttps://www.badcaps.net/forum/images/smilies/icon_smile.gif.
Any guidance, ideas, or constructive criticism would be greatly appreciated.
If I need to post pics of the Boards or P/N's just let me know.
Thanks fellas
. The 24V still drops when I disconnect the ribbon cables that connect the LEDs to the LED Driver.
Let me know if something is still fuzzy and I'll try my best to explain.
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