The first thing I did was remove the back panel from the TV. There are many Phillips screws and they're not all the same size so I made sure to keep track of which ones went where. I also had to be careful lifting the panel off because the speakers are housed in there and they are wired to one of the internal circuit boards.
As noted in most, if not all, of the the posts and videos regarding the Toshiba, the problem lies with a chip that overheats and causes the flickering/blinking screen. I noted that some fixes involved replacing the entire board (pictured below) while others focused on desoldering and removing a small plate over the chip and either attaching a small heat sink to the chip or replacing the thermal paste between the plate and the chip. (One commenter claimed that turning the video settings down solved their flicker issue but it didn't work for me).
The plate in question is circled in red in the upper left-hand corner of this image:
If you turn the board over you will see the four points that secure the plate to the board. If you have a soldering iron and are confident that you won't harm the board then I think attaching a small heat sink might be the way to go to achieve a fix. I haven't soldered anything in many years and when my single attempt with a 30 watt iron didn't immediately melt the solder I decided to try a different angle.
Since the problem is with overheating I wanted to see if leaving the back panel of the TV would have any effect on the problem. Sure enough, I was able to leave a video playing at least an hour with no issue. I would feel pretty good about leaving the back panel off if it didn't contain the speakers. If you're using a sound bar or other external speakers you can probably stop right here but my friend needed the TV to have its own sound.
So how to keep the chip cool once the panel is put back in place? I took a cooling fan from a broken desktop PC and found instructions for converting it to USB power so that it could run off the TV's USB port. Next I measured the approximate distance of the plate/chip from the back panel's screw holes so that I could drill some holes in the plastic panel above the chip. I reattached the back panel to the TV and finally I attached the fan, blowing outward, to the panel with some packing tape. If you look closely at this image you can see a couple of the holes behind the fan:
I turned on the TV and left it playing for over two hours and the problem appears to be solved. The next morning I unplugged the fan and the TV again performed without issue. Maybe drilling the holes provides enough additional ventilation and the fan isn't even necessary. I did note that the room temperature was only 73° in the morning. If the ambient temperature rises I think the fan may be necessary so I'm glad it's there.
Final thoughts:
- Packing tape may be an inelegant solution but the fan is behind the TV so no one is going to see it. If you want it to look better you can use epoxy or screws to keep it in place.
- You may not have a spare fan from an old PC but you can purchase one for as low as $4. Keep in mind you'll also need an extra USB cable to cut and attach to the fan (see the link above again for instructions). It might be easier for you to buy a fan with USB power.
- If you need the TV's USB port for a Chromecast or Firestick you probably have an extra USB charger laying around that can power the fan.
