System Faults - ADEMCO LST700 Series Insallation & Maintenance Manual

1.3 System Faults

System faults are unique in that they do not automatically clear when rectified. A total of three
different types of system fault can occur - watchdog fault, site memory corruption fault or PLL
(phase lock loop) fault.
■ To find out which type of system fault has occurred:-
1. Remove the Panel's lid using the torx key provided and press the ACCESS LEVEL THREE
FUNCTIONS button on the Main Control PCB to gain access to the panel's engineer functions
(see below). Note: If pressing the ACCESS LEVEL THREE FUNCTIONS button (or any other button)
does not cause any change in state, the Main Control PCB is faulty and must be replaced.
2. Continue pressing the ACCESS LEVEL THREE FUNCTIONS button until the SYSTEM FAULT light pulses.
If there is a Watchdog Fault, Zone 1's fault light will be lit.
If there is a Site Memory Corruption Fault, Zone 2's fault light will be lit
If there is a PLL Fault, Zone 3's fault light will be lit
To escape access level three press the ESCAPE ACCESS button at any time.
For a detailed description of what each fault is and suggested action on how to cure it see below:-
■ Watchdog Fault
This type of system fault occurs when the panel's microprocessor has failed to operate
correctly (perhaps due to excessive electrical interference) and the panel's "Watchdog" circuit
has been unable to bring it back under control. A common symptom of this is the panel's
controls locking-up.
Suggested action:
Press the panel's RESET button and, if still in access level three, the ESCAPE ACCESS button.
This should clear the fault. If the fault persists, the Main Control PCB is faulty and must be replaced.
■ Site Memory Corruption Fault
This type of system fault occurs when site specific data retained in the panel's microprocessor is
found to be corrupt.
Suggested action:
(a) Check all the site specific data (delays, disablements, etc) at user and engineering level.
The System Set-Up Data Chart on page 13 of the User Manual / Log Book will include much of
the information you need to do this.
(b) If errors are found, reprogram the panel accordingly to clear the corruption.
(c) If no errors are found, temporarily change some data. For example, disable zone 1, exit
user mode and then re-enable zone 1 to return to the original settings. This should clear the
fault. If the fault persists, the memory is damaged and the Main Control PCB must be replaced.
■ Program Memory Corruption Fault
This type of system fault occurs when the microprocessor's memory is found to be corrupt.
Suggested action:
Reset the panel. The fault will clear. Wait for 2 minutes, if this fault re-occurs then the memory is
damaged and the Main Control PCB must be replaced. (If the fault does not re-occur, then there
was a momentary disturbance during the microprocessor's self checking routine and no further
action needs to be taken). If the fault persists, the Main Control PCB is faulty and must be replaced.
LST700 SERIES INSTALLATION & MAINTENANCE MANUAL • Approved Document No. DFU7002012 Rev 4
SYSTEM REPEATER
FAULT FAULT
SW8
COINCIDENCE
ACCESS
NONLATCHING
LEVEL THREE
FUNCTIONS
OPEN SHORT
CIRCUIT CIRCUIT
DELAYS TEST
LST700 SERIES FIRE ALARM PANEL
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