Instruction manual

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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

55V 5V

65V

7 0V .735V

Q1 Voltage Voltage

Pin No Sound Sound

E0 0V

B 0V .355V

C9V 9V

E B C