Hi @frescard
To check if it is temp related, remove the back cover and use a fan to cool down the boards.
Try placing the fan so that it cools one board at a time more than the other boards so as to try and isolate the problem a bit further.
With a bit of luck if it always seems to be associated with one board then the [https://www.manualslib.com/manual/3349182/Sanyo-Lcd-19e3.html#manual|service manual] will possibly help.