It can only be a bad connection or one of the 'new' boards you put in was faulty. Start swapping back the old boards one at a time. Make sure any ribbon cables are properly seated.
This Tip I wrote a while back explains the problems you face.
https://www.fixya.com/support/r29790007-repairing_own_television
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There could be a few possible issues causing the black screen on your Vizio M3D550KD. Here are some troubleshooting steps you can try:
Make sure all cables (HDMI, component, etc.) are securely connected to both the TV and the source device (e.g., cable/satellite box, DVD player, gaming console).
Try using a different HDMI cable to connect your source device to the TV, as the cable may be faulty.
If possible, test the TV with a different source device to see if the issue is with the TV or the original source device.
Unplug the TV from the power outlet, wait for a few minutes, and then plug it back in. This can sometimes reset the TV and resolve temporary issues.
Check the TV's menu settings to ensure the input source is correctly selected. Use the remote control to navigate through the TV's menu and adjust settings if necessary.
Perform a power cycle by turning off the TV, unplugging it from the power source, and holding down the power button on the TV for about 10 seconds. Then, plug the TV back in and turn it on.
If none of the above steps work, there may be a hardware issue with the TV itself. In this case, it is recommended to contact Vizio customer support or a professional technician for further assistance.
If you have replaced all the boards in your Vizio D50u-D1 TV and you are still experiencing no sound and a blue screen, it's possible that the issue lies with a different component or a configuration setting. Here are a few troubleshooting steps you can try:
1. Check the audio settings: Go into the TV's menu and verify that the audio settings are correctly configured. Make sure the volume is not muted and that the audio output is set to the appropriate option (e.g., internal speakers or external audio system).
2. Check the input source: Ensure that the correct input source is selected on the TV. Sometimes, selecting the wrong input can result in a blue screen and no sound. Use the remote or buttons on the TV to cycle through the available inputs.
3. Test with different sources: Connect different devices (such as a DVD player or game console) to the TV using different cables. This will help determine if the issue is specific to one particular source or cable.
4. Perform a factory reset: Resetting the TV to its factory settings can sometimes resolve software-related issues. Refer to the user manual or Vizio's support website for instructions on how to perform a factory reset.
5. Update firmware: Check if there are any available firmware updates for your TV model on Vizio's official website. Updating the firmware can potentially fix bugs or compatibility issues that may be causing the problem.
6. Contact customer support: If you have exhausted all the troubleshooting steps and the issue persists, it's recommended to contact Vizio's customer support or seek assistance from a qualified technician. They may be able to provide further guidance or arrange for a repair if necessary.
Remember to exercise caution when working with electronic devices and consider seeking professional help if you are not comfortable performing the troubleshooting steps yourself.
If you have already replaced all the boards in your Vizio D50u-D1 TV and are still experiencing the same issue of no sound and a blue screen, it simply indicates a internal deeper underlying issue with the TV's internal components or firmware that requires a professional repair or assistance by any professional.
Turn on the TV or device you want to use with the universal remote.
Press and release the TV button on the RCA Universal Remote. (The red light on the remote will begin to flash)
Now simultaneously press and hold the Power and TV buttons on the RCA Universal Remote. The on/off button will be illuminated and then turn off. After a moment, the button will relight, it should remain on.
Aim the RCA Universal Remote at the TV. Release both the on/off button and the TV button on the RCA Universal Remote simultaneously.
Next, press and release the Play button on the RCA remote. The TV or component should turn off after about five seconds. If there is no response, continue to press the Play button until the TV or other device you are programming turns off.
Now press the reverse button. If the TV or device does not turn back on, continue to hit the reverse button until it does.
Press the stop button once the TV has turned back on, this will save the programming settings.
try taking batteries out of remote then unplug tv then plug back in then put batteries back in remote then try to turn on with button on bottom back left side of tv
Hi Anna, this set has local dimming so one strip can fail and the rest remain lit, also it only has 4 strips, one out will make that section quite dark, more so than a set with 10 or 12 strips, new lamps should fix it but replace them all not just the bad one(s).
Not sure what you're talking about when you say "I did test the replacement t-con board after replacement and via the drain, source and gate diode and it tested bad". What exactly tested bad? Where are you finding a MOSFET you say you tested? Also what is a "gate diode". As far as a panel being bad, there are ways to test it but you will need some kind of costly test gear to test it. One thing you can do is remove one flat ribbon connector at a time that goes to the panel boards and see if you get half a picture, if you do the panel is bad.
