Commercial in confidence 85-909
PLB service manual Issue 4 Page
3.2. Functional tests
Self test
1. Slide a finger under the red anti-tamper cover, press and hold down the
OFF/Test button
2. The red LED should come on
3. After approximately 10 seconds the green light must flash 3 times and the buzzer
must sound three times to confirm self-test has passed.
NOTE: If the unit fails self test then:
a. Repeat the test but place the unit on a flat surface (do not hold it) - sometimes the
hand can cause changes in the RF matching of the antenna – consequently self test
may fail.
b. Check that the pin holding the antenna in position is made of black plastic (the early
units had stainless steel pins – these were found to sometimes change the RF
matching of the antenna). Replace steel pins with plastic.
Live test
NOTE: As the tamper cover must be removed for access to the ON button, this test should
only be performed if there is doubt about the result of a self-test.
1. Press the ON button for at least one second
2. The red LED lights continuously
3. Confirm the buzzer sounds regularly every few seconds
4. Without delay, press and hold the OFF button until the red LED extinguishes and
stays off (approx 3 seconds)
This must be done within 120 seconds to avoid a live transmission.
If the red LED starts to flash, a live transmission has occurred –
refer to Section 1.5 immediately
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