[Solved] Samsung BQ1S4T133 Electric Oven - Error E83: Communication Issue between Main Board & Display

Hello dear forum members.
This error has started to appear in the oven for some time (E83 - no communication between the main board and the display electronics). Then nothing works (heaters, fans, backlight), only the clock and function selection work. Unplugging the power cord for a few minutes helps. But unfortunately the problem appears after some time.
I checked the heaters and fans - all working. I pulled out the plugs on the motherboard, cleaned the contacts, checked the continuity of the beams. Maybe someone has dealt with this problem (a very common condition). The service only exchanges plates, the mainboard costs over PLN 400, the other is the display board. Unfortunately, the oven has been in use for over 5 years, so long after the warranty.
Greetings, Grzegorz.

Have you checked the soldering?
Especially on the chips and the connector.

Yes, I checked it, but still prophylactically rewrites the connections.

Hello, I will dig up the topic a little bit, did you manage to fix the oven?

Knock, the oven goes unquestionably to this day, the error no longer pops up. So, cleaning the contacts on all connectors helped.

And unfortunately the problems started again. You can't use the oven at all. Immediately after setting the baking switches off and on alternately, no error pops up. Only when I turn it off the network, after turning on, sometimes E83 will appear and sometimes it will turn on correctly. I have the impression that the main relay control is broken, which separates the phase into the other relays. I have no idea how to go about it, where to start. I checked soldering on processors (both boards), on connectors, they are all ok. Anyone can advise something?

I exchanged six electrolytes on the power module, followed by circuses. The main power relay was the most suspicious to me because it releases and interrupts 230 V which is divided into other relays. The voltage that is fed to the coil of this relay is about 11.8V and when the light in the chambers or the heater is switched on it drops to about 10.9V. And here is a strange thing, when the oven turns itself off during operation (the lights go out, the heaters stop heating, the fans turn off), then the voltage is applied to the coil of this relay and he releases anyway. To check it, I connected a 12V car relay in parallel to check if the main relay was releasing or it would also release. And here I can not check because after such a connection the oven works normally and does not turn off by itself without any reason .. The main relay works properly. I bet on cold solder in the coil of this relay. I will be testing his work tomorrow.

Subject resolved, the main culprit for the oven not working was the power relay (230V power line). Although his coil was still powered by 12V, he let go of the working contact and cut off the 230V power supply to the other relays (heaters, fans, lighting). I connected a second relay in this line in parallel and the oven works without any problems. Interestingly, the damaged relay also works correctly.

Added after 2 [minutes]:

Damaged T9AS1D22-12 relay