Advertisement
DIALER TEST (Using a power supply)
1. With the power supply OFF, reconnect the test circuit as shown in Figure 6-12. Position the PC board so
that the hook switch is not depressed (off hook).
2. Set the voltmeter to read 48VDC. Turn the power supply ON and adjust it for 48VDC on the meter.
3. Switch tone/pulse switch to the tone position.
4. Put the receiver to your ear and push the "1" button. You should hear a click. This is the result of the loop
current being turned off and then back on.
5. Push the "2" button. You should hear a click.
6. Press each of the remaining numbered buttons including the " * " and "#" buttons to verify that each is
operational.
The automatic redial function doesn't work for the tone position of tone/pulse switch.
If any of the above tests fail, then unplug the telephone cord from the modular jack and:
a) Check that the keyboard buttons are seated properly on the contact pad.
b) Check the HM9102 IC. Be sure that it is installed with the alignment notch as shown in the assembly
instructions.
c) Check that diodes D5, D6 and D7 are installed with the polarity markings as shown in the assembly
instructions.
d) Check the ribbon cable for broken wires, check switch S3.
e) Check for bad solder connections and solder bridges. Look closely at the IC and the ribbon cable. The
pads on these components are very close.
7. Switch the tone/pulse switch to the pulse position.
8. Put the receiver to your ear and push the "1" button, you should hear a click.
9. Push the "2" button, you should hear two clicks.
10. Press each of the remaining numbered buttons (from "3" to "0") to verify that each is operational.
11. Press the redial button. You should hear nothing. The phone must go on hook before the number will be
redialed.
12. Press and release the hook switch. Now press the redial button. You should hear the numbers you pressed
in steps 8, 9 and 10 being dialed.
If any of the above tests fail, unplug the telephone cord and check switch S3 and the IC.
13. Have your instructor inspect the dialer circuitry and verify tests performed.
Instructor's approval: ________________________
14. Turn the power supply OFF. Disconnect the power supply and unplug the telephone cord from the modular
jack. Leave the resistor. It will be used again for the final tests.
-25-
Advertisement
