Apartment Building Intercom Troubleshooting


  #1  
Old 05-11-09, 06:01 PM
H
Member
Thread Starter
Join Date: May 2009
Posts: 4
Received 0 Votes on 0 Posts
Apartment Building Intercom Troubleshooting

I am trying to fix the intercom system in my building. There are only 10 units on 2 lines. West and East. My intercom is on the east side and it works fine. The buzzer works, and I can open the door so people can enter the building. On the East side of the building, the buzzer works but the door release doesnt. I have replaced the intercoms in the individual apartments as well as the main system in the basement and the problem persists. Please help!
 
  #2  
Old 05-11-09, 06:14 PM
Tolyn Ironhand's Avatar
Group Moderator
Join Date: Nov 2007
Location: United States
Posts: 14,964
Received 595 Votes on 511 Posts
Not real familiar with these but I'll take a stab - When you hit the buzzer I'm guessing that should activate an electric strike. I would guess maybe you have a bad strike since it buzzes but they can't open the door.
 
  #3  
Old 05-11-09, 06:27 PM
H
Member
Thread Starter
Join Date: May 2009
Posts: 4
Received 0 Votes on 0 Posts
Thanks but the strike is good. 1 because it is new, 2. because it works from my apartment but not on the apartments on the east side of the building
 
  #4  
Old 05-11-09, 07:37 PM
ray2047's Avatar
Member
Join Date: Mar 2006
Location: USA
Posts: 33,575
Received 15 Votes on 13 Posts
Do you have voltage at the strike when a button on the east side. Is the strike on a separate cable from the buzzer?
 
  #5  
Old 05-11-09, 09:21 PM
B
Member
Join Date: Oct 2008
Posts: 1,312
Received 0 Votes on 0 Posts
When did it stop working and who was drilling holes at that time and into which wall? (And drilled a hole into that wire!)

(Follow and test the wires...)
 
  #6  
Old 05-11-09, 09:46 PM
A
Member
Join Date: Oct 2005
Location: Milwaukee WI
Posts: 1,339
Received 0 Votes on 0 Posts
Like any troubleshooting apartment intercoms involve a process of narrowing a diagnosis through elimination. Unless you understand the way things are hooked up, it is a frustrating process. You need a volt-ohmmeter (DMM/VOM) for troubleshooting all but the simplest problems.

Please clarify:

10 apts on 2 lines: You mean two cables? Sounds like this is not a phone-based system and that you have a wall-mounted panel in each apartment unit, a common panel in the lobby, and control unit(s) in the basement.

Buzzer: The "doorbell" signal that alerts a resident that somebody is at the door, right?

Intercom: Are there two separate control units, one for west and one for east? Are they identical? Do you know the manufacturer and model? If not identical, are the strike specs the same? Older units often used a 16 VAC strike. Newer ones might use a 24 V or 12 V AC or DC strike.

Are you able to get the strike to open using the "postal" contacts?

Cables: How many wires are in the cable? Have you checked the cable's "door" or "unlock" wires to make sure you have continuity?

That is, there are usually at least three wires in each unit and coming from the controller: Common, Door, and Signal. From the lobby panel, there is a separate Signal wire to each unit. However the Common and Door wires are shared among all units. These are usually daisy-chained from one apartment to the next, so a break somewhere may affect all units. Here's a typical diagram showing various apartment stations: http://pacificelectronicscorp.com/AF1000.jpg

Has this been a problem for a long time, or did it just quit working recently?
 
  #7  
Old 05-12-09, 02:04 AM
ray2047's Avatar
Member
Join Date: Mar 2006
Location: USA
Posts: 33,575
Received 15 Votes on 13 Posts
Why did you replace the intercoms? Obviously if none work it is not the individual intercoms at fault but some component common to all of them such as a cable or transformer. In fact I think you are miss diagnosing this when you suspect it is an intercom problem. It is instead a problem with the door strike circuit as ArgMeMatey has pointed out.

There are really only two possibilities since the strike does work and it is extremely unlikely that all of the apartment switches are bad. Either the transformer is bad or the wiring is bad. It is unlikely a transformer problem since the same transformer probably powers the strike for both wings and the strike works for one wing. That leaves simple trouble shooting of the wiring.

Do you have power at the buttons on each individual control panel? Then you know the transformer is ok and the cable is ok to the panels.

Does the power go from the individual panels back to the main control unit and then the door strike? If so check that power is returning to the main control unit. If that cable seems dead disconnect at both ends and confirm a problem by twisting the wires together on one end and checking for continuity on the other.

If how ever you found you had power from the main control unit and back to the main control unit then you know the problem is in the cable between the main control unit and the strike. Again you can check by disconnecting at both ends, twisting together at the other and checking for continuity. No continuity it is bad.

One last possibility. Are the buzzer and strike on the same wire? If so since you know the buzzer works then you can assume the power goes first to the buzzer then the strike and the wire between buzzer and strike is bad.

In all cases where a cable has been determined bad if there are no unused wires it is best to just replace.

Great explanation but only based on guess of how such a system would work. I could be very wrong so wait for ArgMeMatey to comment on my post.
 
  #8  
Old 05-13-09, 08:16 AM
A
Member
Join Date: Oct 2005
Location: Milwaukee WI
Posts: 1,339
Received 0 Votes on 0 Posts
Originally Posted by ray2047 View Post
Do you have power at the buttons on each individual control panel? Then you know the transformer is ok and the cable is ok to the panels.

Does the power go from the individual panels back to the main control unit and then the door strike?
Typically the door strike cable is separate from all of the rest, so the lobby panels and apartment wall units never "see" the strike voltage. The controller just watches for a short when the "unlock" button connects the intercom wire to the common.

The easiest way to troubleshoot strike problems is to wire a toggle switch directly across the controller postal contacts and when you close that switch, check for proper voltage and delay timing on the strike contacts. If that is OK, have somebody press an apartment intercom button while you check the strike contacts. So start there and report back.
 
 

Thread Tools
Search this Thread
 
Ask a Question
Question Title:
Description:
Your question will be posted in: