Security & Fire Protection Systems/DCS PC1550 CONTINUOUS HIGH PITCH BUZZ


Hi Dave,
I read through the responses and couldn't find similar question or response. I hired a contractor to replace the backup battery before therefore I try to give a shot this time. I had a power surge. The alarm was dead quiet and no LED from the keypad. I opened the PC1550. Looks like aux fuse 1A was blown and I replaced with a spare 1A fuse in the box. I have 1 1A and 1 5A spare. After I replaced the aux fuse, I got a continuous high pitch buzz with all zone LED on with red. I found DSC PC1550 installation manuals but couldn't find the possible problem and how to clear it. Please help. Thanks, Dennis.

Hello Dennis, and thanks for writing.

Try this first... unplug the transformer, and then the battery.

Wait a few minutes, and then plug in the transformer and reconnect the battery. This is a "hard re-boot." If this clears the trouble, then you're good-to-go.

On the other hand, if you have the same symptoms as before, then either the control is damaged, the keypad is damaged, or both are damaged.

Probably best to have a technician troubleshoot that for you. The only way you'd be able to troubleshoot the problem is buy a new keypad and try that, understanding that if the control is bad, you'll have to replace that too.

I hope that helps!

Best Regards,


Security & Fire Protection Systems

All Answers

Answers by Expert:

Ask Experts


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.


©2017 All rights reserved.