I have a DSC PC1550 that is not monitored and has worked fine until recently. However, a short while ago, the siren simply stopped working when the alarm is tripped. It won't go off, whether in delay mode or not. Everything else about the system seems to work fine, just the siren does not sound. Any ideas on an internal system problem, as I don't think that any wires have been cut, etc...? Also, It doesn't appear to be the bell fuse, as I can visually verify the fuse is intact.

Thanks

 

The siren itself probably failed. It's a 12v powered tone generator board connected to a heavy duty speaker. The output side of the circuit probably went. The replacement will run you about 25-35 dollars. You might have a seperate siren driver card, in which case it could be either the card or the remote speaker it's connected to.

 

Thank you so much for the prompt reply. Is there any way to test and see which it might be? I have a second smaller board mounted vertically inside the main alarm control box, perpendicular to the main board. However, it appears to be the wiring for the individual zones, as the wires feed back to the wiring bus on the main board. Is there any way to test the speaker by bypassing the board, or do they have to work together? If there is a separate remote board, I assume that it would be remote to the speaker and should be mounted in the control box? If it is the speaker, I should be able to simply replace the speaker itself, correct?

Thank you in advance for your help.

 

First, if the wires going to the small board are from the bell output terminals (these driver boards are usually playing card sized), then you have a speaker/driver card system. If the wires go directly from the bell output to the siren, then it's a self contained 12v siren.

Testing the latter is easy. You put a meter on the bell output, and trigger an alarm. If there's 12vdc at those terminals, then the alarm is doing what it's supposed to. If you have 12v at the leads coming into the siren, but no noise, then the siren has died, buy a replacement.

If you have the component system, you check for 12vdc from the panel to the driver board. To check the speaker you use an ohmmeter and look for 8ohm resistance, or simply touch the speaker leads to a 9v battery. If it makes a pop then the speaker is good. It's just a normal 8ohm speaker, they just use a heavy coil. The same speakers are used on PA systems.

 

Thanks again. I'll give these suggestions a shot and see what happens. I appreciate all the help.

 

I grabbed a VM and checked the power across the bell screw terminals in the main alarm box. It read 13.37 VDC when I tripped the alarm, which looked good. However, when I climbed into the attic and cut the wires running to the siren, they read 2.5 VDC. I looked at the wire and followed it back to the box, it doesn't appear damaged. Also, the siren reads 7.5 MOhms and does not pop when a 9V battery is applied to the leads. I bought a new siren with the same rating as the old (12V, 30W). I checked the siren with a battery and it pops as expected. I installed it, but still get no audible alarm. The trouble light is now showing on 3 (blown fuse on AUX or BELL), but the fuses appear in order. I have 12 volts across the bell fuse, but a low reading <1 V across the bell screw terminals when the alarm is tripped, versus the 12 volts I had before replacing the siren. Do I need to reset the system somehow? Any ideas?

 

12volts _across_ a fuse means that it's open/blown. Somehow in what you were doing, you threw a short across the siren output.

 

Wow you were answering questions late. Thanks for the dedication. Now for the mea culpa....if I had been thinking (should have been thinking), I would have realized that the change in voltage meant a blown fuse (even though it visually appeared okay). After all, the fuse should read as a short (0 ohms with no voltage change). Oh well, live and learn. I'll find another fuse to replace this one and see what happens. I'll keep you updated. Thanks again for your dedication.

 

Well, it appears that you were correct. A new siren and a new fuse fixed the problem. The only problem I have now is finding the exact replacement for the fuse. The old fuse was a 5x15mm 5A 125V. I have checked all over town and the only thing I can find that is 5A 125V is a 5x20mm fuse. The larger size works, but is not what I really what I want to leave in the box. I'll see if I can find the correct size and order via the Internet. Thanks again for all your help.

 

Those mini fuses can be a pain to find. _I_ have trouble finding them, sometimes.