Just assembled Traffic Light Kit MK131. Everything works well except the middle row of red, yellow, green lights don’t illuminate, there is no voltage at the pads of the circuit board for LD1, 2, 5, 6, 9, 10.
Dear,
Recheck the polarised components. And especially transistor T3. This looks the same as T1 and T2 (Same TO-92 housing) but T3 is not the same as T1 or T2. Possibly it has been swapped with T1 or T2.
Check if the LEDs are polarised correctly.
Also check the solder joints. Below is an example of correct soldering:
Best Regards,
Velleman Tech Service