Start mounting the via's on the PCB.

Following by the sockets for the IC's

Then mount the resistors and the condensators + transistors, and so on.

Be aware that the 7 Segment and the keyboard + the 2 LED's + the potentiometer and the 2 push button's shall be mounted on the Rear side of the PCB, see picture below.

Remember to put a cooling plate on the 78s05 , place it on the outside of the box , about 2*10 cm.

Due to a error in the PCB layout, 2 of the resistors for the 7 segment, have to be crossed, se following picture.