Instruction manual

-8-

TEST PROCEDURE - BLOCK 1

Procedure 1

If you do not have an audio generator and

multimeter, skip to procedure 2.

Power Test

Make sure that the power switch is in the OFF

position (handle away from the 2 wired terminals).

Connect a fresh 9V alkaline battery to the battery

snap. Set the multimeter to read on the 20V scale

and connect to the circuit as shown in Figure 10.

Connect the positive voltage probe to the positive

lead of capacitor C4. Connect the common probe to

the negative lead from the battery. Turn the power

ON. The multimeter should read between 4.5V and

5.5V. If not, turn off the power and check that U3 is

correctly installed. Also, check for solder shorts and

unsoldered leads.

Audio Gain

Make sure that the power switch is in the OFF

position. Connect the audio generator and

multimeter as shown in Figure 11. Turn the volume

control fully clockwise (maximum gain). Put the

multimeter in the AC 20V position, turn the

generator to minimum at 400Hz sine wave output,

and turn the power ON. Slowly increase the

generator output until the multimeter reads 2Vrms.

Move the multimeter lead to the generator output as

shown by the dashed lines in Figure 11. Adjust the

multimeter for the best reading and record here:

Input Voltage = ___________________

The gain is the output voltage divided by the input

voltage. Since the output voltage was set at 2V, the

gain is equal to 2 divided by the reading recorded

above. Gain should be approximately equal to 17.

If gain test fails, turn off the power and check the

connections on all external parts. Check for shorts

between pins on IC U2 and make sure that all of the

IC pins are properly inserted in the socket. Replace

the battery with a fresh alkaline battery.

Figure 10

20A

COM

ΩΩ

9V Battery

Temporary Connection