Beginner’s Principles that I think of the short cut to pass the exam.

>> Drawing [pattern diagram]

1. Minimal jump lines for the short connection.

2. In last, check VCCs and GND.

>> Locating in board

1. Check negative and positive terminals in LED.

2. Check sockets of top position.

>> Soldering

1. Check VCC, GND every IC.

2. Check main point with multi tester.

3. It is important to solder in connected point. If you have not a suspicion, try to again to it.

4. Jump lines are essential, practice many times.

5. Compare connection points against circuit diagram.