Chosen Solution

Video: Yesterday my TV decided to stop working and I’m having trouble diagnosing the issue. Here’s a video of the issue: https://youtu.be/F8IWaukZyHg Description: The TV will work properly for around 30-60 seconds. Then the sound will briefly slow down before the TV “crashes”. It stops responding to the remote (normally a light below the TV flashes when a remote command is received) and a whining noise can be heard at the rear. After this happens, unplugging/replugging the TV in will cause the power LED to light, but there’s no picture, sound or responses to button presses/remote. Disconnection from power for 10 minutes or so is the only way to get it to show an image again, followed by the usual crash. I’ve opened it up check cables and capacitors but all seems fine. Thoughts: Due to the slowing of sound just before it crashes, I feel it may be a lack of sufficient power to the TV, either the fault of the external PSU or the power board in the TV itself. This is simply based on how other devices react to low power though, I’m not an expert by any means! If you have any ideas then please let me know! I’d like to figure out the cause before I start randomly buying replacement parts in an attempt to repair it. EDIT: As requested, here are some pictures of the TV’s boards. Inverter board;

Inverter board Caps:

Side Main Board:

Main Board:

TCON:

TV Overview:

@oldturkey03 I thought you may be interested to hear what happened! Trying to find/replace the defective part, I ordered a new mainboard from eBay in the hopes that replacing it would fix my issue. But the board I received turned out to be from a different model (the 52" instead of 42").This turned out to be a blessing in disguise, as putting it into the TV prevented it from booting up normally, and it instead flashed an error LED indefinitely. Under normal circumstances the TV would attempt to boot, then crash shortly afterwards. As this happened so quickly, the TV wouldn’t take commands from the remote. Thanks to the wrong mainboard, the TV is able to take commands from the remote while it’s in it’s error mode! This allowed me to send the Factory Reset command (Hold UP on the remote while pressing the TV’s power button). When I did this, the TV froze and required me to pull the power. I put the correct mainboard back inside, and it refused to even turn on. I was sure I’d killed it for good. But I left it disconnected from the power for a few hours, reconnected it and it FINALLY booted up, with it’s settings completely reset. Since then it’s been on for about 24 hours instead of the usual 1 minute! It did crash once, but instantly reset itself instead of the usual freeze. Googling around I found someone else with the restarting issue who recommended turning Wifi off, which I’ve now done. I’ve had 0 issues since doing so and am happy to have my TV back :) So after all that, it all seems to have been a software issue. For anyone else with this issue, attempt a factory reset and disable Wifi!

@hellsplumber the soldering of caps on the LD board look odd.Your LD board is a14STM4250AD and that is where I would start. Check the connector CN4001 against the image. On the image it is listed as 2001 but should be the same connections and voltages as your board. Let us know what you find.

Update (01/17/2018) @hellsplumber does this look like your TV’s board layout? If not, any chance you can post an image of it with your question?

Update (01/17/2018) There should be a T-con board T420HVN06.2 somewhere

hi first. up date new version give from site sony . second . test out pot complat voltage from power bord and test dont riple on voltage .