Test 1D: Power supply of IC sockets
+5v
GND
U2 pin 14
U3 pin 14
U4 pin 16
U5 pin 16
U2 pin 7
U3 pin 7
U4 pin 8
U5 pin 8
Figure 2. Measuring power supply of IC sockets in Test 1D.
Test 2A: Buzzer oscillator
With Tests 1A, 1B, 1C and 1D, you have verified that the proper power supply has been
delivered to the IC sockets and there are no severe abnormal conditions of the power
supply. You are ready to energize the ICs. Tests 2A and 2B verify the two oscillators of
LM556.