Security & Fire Protection Systems/comm error


I have a FBI XL-3 security system with a 7005 lcd keypad.  After a power failure, when the power returned i get a comm failure message on my display and the unit will not arm

Hello Tony, sorry for the delay in responding.

Your panel dates back to the early 90's, so given its age, it's always possible that the motherboard has failed.

That said, there are a few things you can check. First, the COMM Failure means that the control attempted to contact its monitoring center, and failed in that attempt. The most common cause for this is a phone line failure (although these days with people cutting the land-line, it's often a matter the land-line not even existing).

The fact that you can't set the alarm is more troubling, especially so because you did not say that there were faulted zones.

So the best thing to do is to ascertain whether the system is properly powered, and that means both AC power (which I assume was restored) and the backup battery. If you have a meter, measure the voltage on the battery terminals, then remove the AC power and take a second reading. The first reading should be a little above 12 volts; the second right around 12 volts. Leave the AC unplugged for a few minutes -- if the battery is no good, you'll see a rapid dropoff in the battery voltage.

If the battery is bad, you'll need to replace it and the risk here is that if the panel has failed, a new battery won't make a difference. But there's no good way to find out ahead of time.

If the battery is still good, then you can try a system reset. This is done by removing ALL power from the control -- both AC and battery. This is similar to re-booting a computer.

Let me know what happens, or if you have additional questions.

Best Regards,


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Dave Neuweiler


The design and application of burglary and fire systems for homes and businesses. Helping alarm owners understand how their system works. Helping to troubleshoot false alarm problems. Questions about monitoring issues.


Over a quarter century in the industry. Experience in installation, service, and monitoring centers. Training manager for a national protective services company; director of education and training for a national trade organization for for alarm dealers.


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