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RINGER TEST (Using a Power Supply)
Test Equipment Needed (not provided)
• 9VDC power supply.
Since capacitor C1 blocks the DC voltage, it is shorted for this test (Figure B on page 11).
1. Set the ringer switch to the OFF position (refer to Figure 6-2b).
2. Check to see which modular jack, type A or B, has been included in your kit.
If you have type A, then use Figure 6-5a for testing. If you have type B, then
use Figure 6-5b for testing.
3. Connect the modular jack wires to the terminals on the power supply (as
shown in Figure 6-5a or Figure 6-5b.
9VDC
Power Supply
+
9VDC
Power Supply
+
Perform the following Ringer tests:
4. Turn on the power supply. Set the ringer switch to ON (toward the center of the PC board). You should hear
a 3kHz tone from the buzzer. If no tone is heard, unplug the telephone cord from the modular jack and:
a) Check that the power supply is connected with the right polarity as shown in Figure 6-5a or Figure 6-5b.
b) Check that the buzzer is wired as shown in Figure 6-3. Check that the telephone cord wires are
soldered correctly.
c) Check that transistor Q1 is a 9014 and is mounted with the emitter, base and collector leads as shown
in the assembly instructions.
d) Check that R5, R6 and R7 are the correct values.
e) Check for bad solder joints and solder bridges.
5. Put the ringer switch to OFF (toward the edge of the PC board). The 3kHz tone should stop. Put the ringer
switch back to ON.
6. Turn the power supply OFF. Reconnect the power supply with the wire to the positive terminal and the wire
to the negative terminal reversed. This simulates the negative portion of the ringing signal. Turn the power
supply ON. No tone should be heard from the buzzer.
7. Have your instructor inspect the ringer circuitry and verify test performed.
Instructor's Approval: ___________________________
8. Unplug the telephone cord from the modular jack. Cut the leads from C1 (Figure B on page 11). This
removes the short from capacitor C1.
9. With the ringer switch ON, reconnect the circuit as shown in Figure 6-5a or Figure 6-5b and plug the telephone
cord to the modular jack. Since the capacitor now blocks the DC, no tone is heard from capacitor C1.
10. Turn the power supply OFF and disconnect the power supply from the modular jack wires.
Type A
Green
Modular Jack
Red
Type B
Red
Modular Jack
Green
Figure 6-5a
Telephone Cord
Figure 6-5b
Telephone Cord
-14-
Type A
Type B
Green
Red Red
Green
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