The main problem is that pressing the power on button don't do nothing visible.
The other monitor is at work (this faulty display is also from work), it was bought for the service at 2018, so it has 2 years on site.
Tomorrow I may open the good one.
When I test the good working monitor, I did some measurements.
Between power supply board and the controller board, there is a 6 wire cable with this sequence:
Red, empty, red, black, black white and brown
Both Black wire is DC ground
Both Red wire as soon as the power AC is connected, stay at 18.56V (working monitor 19.01V)
White wire and brown wire voltages in the voltmeter are varying but in the mV scale (auto), pressing the power button nothing change.
BUT, in the working monitor the situation is different:
Both red wire as soon as power is connect, the voltage is 19.01V
White and brown wires voltage oscillating in the mV scale.
Pressing the power button the led lit white and the brown wire voltage ramp up to 3.3V but the white wire stays oscillating in the mV scale.
The monitor search for video signal and not finding it, suspend.
The led change to amber
Brown wire voltage become mV oscillating, white continues with its voltage oscillating.
The last test I did, connect the video from the computer and with image in the LCD the voltages become:
Brown wire: 1.054V
White wire: 3.170V
Red wire (both): 18.75V
Can someone explain, in simple terms, how after pressing the power button, the LCD power up?
The signal from pressing the power button (The test point voltage is 3.356V, pressing the power button the voltage become almost zero, 0.1mV) is transmitted to the controller main cpu (RTD2525AR) ?
Sorry for this long post...