Security & Fire Protection Systems/Trouble Light


QUESTION: I have a DCS PC 1550 security system.  Just changed phone companies & now the trouble light is on showing the trouble to be AC  power problem.  Do not believe the technician did anything to the power source.  Ready light is on as though it is still powered.  I unplugged the phone line to the main control box.  Trouble light did not go off.  I then disconnected the battery.  All lights went off, so it must be powered by the battery only.  I want the alarm to work, but not sure how to get this light to turn off.  Your assistance is appreciated.  Thanks

ANSWER: Hello Paula, and thanks for your question.

There are only a few things to check when there's an AC Power issue. First, you'll have to find the AC Transformer (it's 16.5 volts, so there's not much of a shock hazard). It will be plugged into a wall outlet that's near to the main control panel. It's usually beige in color, and about the size of two cigarette packs.

When you find it, feel it; it should be warm to the touch. If it's cold, then get a table lamp or some other small electric appliance and plug it into the wall outlet to make sure the wall outlet is itself powered.

If the outlet is powered and the transformer is cold to the touch, you'll have to replace the transformer.

If you have a warm transformer, then the only thing to look at is the wiring between the transformer and terminals 1 and 2 in the control. Look at the connections at both ends; sometimes a wire will break right at the screw terminal. If the connections are okay, then there's a cut or break in the wiring between the control and transformer.

If checking these things doesn't locate the problem, write again, and let me know what you did find.

Best Regards,


---------- FOLLOW-UP ----------

QUESTION: Thank you for your fast response.  I do not have a power source next to my control box.  There is a large box in a closet containing lots of wires & the phone jack. The wiring goes thru the wall & seems to go to the fuse box in the garage.  Fuse is OK.  Checked that first.  Does disconnecting the phone service have anything to do with this?  The system worked perfectly until I dropped my land line.  If so, how do I correct this?  The system is now on battery back up & I know. It will stop working completely when the battery dies.  Thanks.

Typical  Alarm Transformer
Typical Alarm Transfo  
Hello again ...

No, changing the phone service would not have an effect on the power, unless the phone technician inadvertently disrupted your power.

You still need to find the transformer; I've attached an image of a typical one to help.

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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