Tutorial with component identification for UCH N1 / N2 / N3
Its based on my repair experience with this units
Some procedures:
1 - Check for all marqued diodes (cold joints, burned diodes, etc)
these are simple 2A SMD diodes like 1N400x series but rated at 2 amps
2 - Check for solders on the 40 pin black connector (reverse side)
3 - Check marked power supply capacitor as well its diode and 5V regulator IC (TLE4269)
4 - Very important resolder each Array IC ULN2003 ( can be other reference)
5 - Very Very important Resolder MCU / CPU with hot air or a very small iron tip with flux. Remind you this is a dangerous step as pins could solder each other! Use a magnify tool to check and re-check!
6 - Search for other cold joint over the main board
PS - I ve repaired dozens of this units without replace one relay. they apear to be very solid and reliable.
