Elenco Motion Detector Kit - Manual (Page 15)

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4. Measure the voltages at IC1 when activated.
A. Incorrect voltage readings:
1. Check resistors R3 - R12 for correct value.
2. Check diode D1 polarity.
3. Check C3 and C4 polarity.
4. IC1 may be defective.
SOUND GENERATOR
Measure the voltage at the following pins on U2, as listed in the chart below.
A. No voltage at pin 3:
1. Check R13, R14, SW1 and C5.
B. No 5V at pin 5:
1. Check SW1 solder connection.
2. No 5V at pin 6.
3. Check C9.
C. Outputs two short tones:
1. Check C5.
Pin Voltage
1 0 - 3.8V
7 0 - 3.8V
8 0 - 3.8V
14 1.5 - 3.8V
U2 Voltage Voltage
Pin No Sound Sound
3 0 0 - 4V
5 5V 5V
6 5V
7 0V .735V
Q1 Voltage Voltage
Pin No Sound Sound
E 0 0V
B 0V .355V
C 9V 7 - 9V
Q1
E B C