The zone input board

The following series of steps will test the zone board, which the alarm system will use to talk to detect changes in the outside world.

Power check

Now that we have completed our visual check of the board and fixed the errors, it is time to apply power to the board.

1. Apply 13.5V DC supply to either J1 or J2 of the board.

2. Connect the negative lead of the multimeter to pin 2 of either J1 or J2.

3. Measure the voltage at the anode (end without the stripe) of D4 or D5, depending on which connector you chose.

4. Make a note of this voltage.

5. Measure the voltage at the cathode (stripe) end of the diode. The voltage should be about 0.7V less than the voltage on the anode. (This is because there is about a 0.7V across the PN junction of most rectifier diodes.)

6. Apply 3.3V (or 3V if you are using batteries) to pins 1 and 6 of J6. Be CAREFUL because there is no polarity protection on this connector. Pin 1 is the positive terminal and pin 6 is the negative or the ground terminal.

7. You should measure...