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dougfms · Jan 1, 2006, 03:16 PM

Hello
I am wanting to install a new transformer for my alarm system. The old one was taken out by a friend and was incorrectly installed according to him (an electrician).
It is a 16.5 V transformer which sat at the bottom of the panel. It has 2 black wires coming from it. There is a place to screw the transformer into the panel at the bottom. I am assuming one of the black wires goes into the main ground bar. However, where does the other black wire go? How does the alarm system setup? This is an older type alarm system.

Is there a place where I can find diagrams for alarms? No spam please!

Thanks

HB

labman · Jan 1, 2006, 04:28 PM

The 2 primary wires go to the incoming 120 volts, I guess after any shut off switch, one to hot, and as you said, the other to the ground. Got to have at least 4 wires. Did the secondaries, 16.5 V plug right into the system? Since it is AC, it doesn't matter which wire is which for either pair.

Can't help you much on the other questions. A simple alarm just has a circuit around the area. Break the circuit, and the alarm trips.

authorjoseph · Aug 31, 2008, 08:25 AM

If it is a 16.5 V DC class 2 transformer it should have 1 wire going to the 12v dc + terminal on your alarm panel, and the other wire goes to ground. I am an electrician and can verify that no class 2 transformers are correctly installed by alarm companies, they work with low voltage, and do not check resistance or ground on the transformer. 90 percent of all alarm panels manufactured between 1980 and now will have the 12V power circuit as the first two terminals on the lower left of the main control panel. If you know the manufacture if the circuit board, you can get schematics and user manuals off the internet at the manufacturers website. Good luck.

Stratmando · Aug 31, 2008, 01:01 PM

Many of the Newer panels have an AC transformer(16.5 volts among others)and is AC 16.5 into Panel, It is rectified/filtered regulated and charges 12 volt(usually)battery, all devices will be 12 volts, when ac is lost, Dc is powering all 12 volt devices, a good setup.
What panel and manufacturer do you have. Many times their will be a legend on cover.

stanfortyman · Aug 31, 2008, 02:35 PM

Strat, I can see it from a new guy, but did you notice the date of this thread?:D :eek:

Stratmando · Sep 1, 2008, 06:28 AM

I saw a response from the same day and responded, Once I clicked "post answer", then I noticed the date. Thanks.

stanfortyman · Sep 1, 2008, 06:39 AM

Don't you hate it when that happens? :rolleyes:

I'm just goofin on you. :D :p

Stratmando · Sep 1, 2008, 07:06 AM

Every time. Take care
Plus I wanted to mention, MOST panels use an AC transformer, and besides the 2 or 3 connections for primary, the secondary can have 2, 3, 4, and 5 connections.
2, is low voltage only.
3, is low voltage and ground.
4, is low voltage and data in and out for PLC control
5, is low voltage, the 2 data, and 1 ground.

red345 · Nov 12, 2012, 08:00 AM

Hello ,

I have a universal class 2 plug in transformer for my security alarm system. Once I noticed that it is really hot not warm . I unplugged it and alarm system is off . What should I do now? Try it one more time OR get a new transformer.
Thank you

hfcarson · Nov 12, 2012, 08:54 AM

First, in the future please respond to the main board with a new post... more will see your
Question.
If this is a small transformer it likely won't cost much to replace. The piece of mind
Would be worth it...

Stratmando · Nov 13, 2012, 06:45 AM

If you unplug the AC and your system goes down, the Battery needs to be replaced or you have a bad connection.
The Voltage should be the same, and the VA's must not be smaller, this may be your problem.