Intercom Problems

http://www.bellsystem.co.uk/contactus.php

Someone came to fix the intercom few months ago. Now, I can hear but I can't buzz in. We should contact Jamie in order to fix this buzzer,

it's kind of an headache ...

http://www.61designstreet.com/

You told us before the intercom uses 12VAC.

You say here "... it is neither a positive or negative and when I put testers on cable it shows less than 12v !?" I'm sorry, but I don't really understand what you are telling us.

What is the distance between the power supply for the (presumably) electric strike? One thing that matters is the length of cable, in total... that is to say, the loop (circuit) formed with the power supply, the switch, and the strike. In addition, are you using this completed circuit to energize (in series) indicator lamps, buzzers...

I am suspecting there is a problem with line loss.

Afterthought: Please tell us
Locking device, manufacturer and model
Power Supply, mfgr and model (might be insufficient amperage)

Everything works fine other than the zero volt negative signal from intercom which releases the door, in this case we want it to create a circuit thus energising the coil on relay, it is about six metres to closest phone, spoke to intercom technical department and they said a faulty relay but the exit button and card reader are in exactly the same terminal and workimg correctly, really stuck as to what to do on this, cannot handover obviously till complete

As Lockduke points out, in your original post (OP) you say magnet (which I did, indeed, miss) which now means to me a bond magnet; that is to say, a magnet that has powerful enough attraction to hold the door secure (unusual for this to be 12VDC). Now you say "...we want it to create a circuit thus energising the coil on relay..." which sounds more like a solenoid in a strike. Please confirm just what you have.

It really doesn't matter. You say "Everything works fine other than the zero volt negative signal from intercom which releases the door...", so the troubleshooting will be clear: the power supply is insufficient, there is an interruption of the circuit (short) somewhere, or there is a faulty or incorrectly selected component in the controlled circuit. That is the long and the short (sorry) of it.

Maybe a little time with Occam's Razor will help.

Is this a new installation ?

If not, did it work in the past ?

When you put your "testers" on the cable, did you test for DC and AC voltage?

If you are measuring onto the relay terminals you will get low/no voltage, most relay terminals on intercoms are for switching and do not produce their own voltage they simply give you either an open(NO) or closed(NC) switch contact. Usually these relay contacts will be put in series with a supply voltage and fed to the door strike.

IE go from the postive 12v supply to the n/o terminal , the from the common terminal to one side of the doorstrike. the negative 12V supply goes to the other side of the doorstrike. When the N/O contact becomes closed ( when you press the unlock button) circuit completes, and door should (fingers crossed ) open...

If it is easier to figure out, the system wiring diagrams are available on net, via google, intercom; type in bell system 801 wiring diagram, card reader is an easiprox stand alone system,, the door magnet is just a positive and negative supply, the relay is a 12v dc 8 pin 2 pole, . I have the supply to mag in n/c with a supply in common, I have the positive permantly on the coil, the exit button switches the negative to terminal 7 and card reader n/o into 7 also, as I understand the z terminal on intercom was to also go in terminal 7, easiest way of doing it as it switches coil when anything is pressed, I hope that can help but will understand if you see wiring diagrams, easy system not complicated just not functioning! Thanks for advice guys

Is this the point-to point diagram you are using?

This is for a fail-secure setup, and is inappropriate for a magnet.

I know you think you are giving us all we need to help, but you are not really telling us the things that are useful.

that is the diagram i am using, it is for a fail safe yes but it is only a signal, if the magnet has a supply on it then the unlock button on the phone only has to interupt the supply, via the relay to fail the magnet no? unfortunately i am an electrician and never attempted electronics before, trial and error! so what is the correct info needed?

There we go! Okay.

Yes, that should work. You have told us everything else is working correctly. When the signal to open is given, does the added relay change state? It might be useful if you can give us the part number of this relay; it may have too large/too small of a coil. In addition, is the supplemental power supply for the magnet putting out AC or DC?

the relay does not change state when the signal is sent from the intercom, however when the signal is sent from exit button and card reader they both activate relay as required, the complete system is dc, part no for relay is 152E12D two pole 8 pin

Okay, we're gettin close to a solution!

Do you have a meter? You need to check the wires coming from the intercom and confirm that DC voltage (acting as a signal in this case) is there. If yes and it is DC, the relay must be traded for another with a smaller coil, and a resistor placed inline with the reader and button.

The 152E/12D is a DC coil. As mentioned, confirm the voltage IS DC. If not, use a full wave bridge rectifier to convert that signal voltage to DC.

If no power from this pair of wires, therein lies the trouble; no signal.

There is only one core from the intercom and this, I am led to believe is a negative signal, I have had the testers on it when activated and of course no power (its negative) however when testers are put across this and positive, when button is pressed (door release from intercom ) it shows 12v dc between that and positive showing a circuit, but not activating coil hence neither a positive nor negative signal

The two cores shown on the point-to-point as going to the lock release 203/204 should run through the coil on you relay. That is the pair of cores mentioned in my comment #26. Be certain the polarity matches your other inputs. Is this what you have done?

yeah this is what i have done, the live for lock is run through the n/c on relay. (negative supply taken straight from power supply) then z on the intercom to the negative side of the coil on the relay as that is "supposed to be a negative signal from phones to unlock the door, there lays my problem as it does not send a negative signal capable of completing circuit to energise the coil, i have even tried to link out "o" on the controller to the negative input on the controller ( making "O" negative)and it still does not work!¬!!!! which is strange because when the unlock button is pressed it has continuity between "O" and "Z" on handset!!! and it is not the run too long as it is far less than 50 metres! no short is on the cable neither (tested),

Where is the relock delay managed for each release component?

That is to say, when you show a credential to the card reader, how many seconds does that particular relay stay altered, and what controls that amount of time? Same question for the other releases involved. I am assuming there are at least two inside releases for this door (required by code in the USA).

This problem has been made artificially difficult. Let's get to the end of this. I am as poor as Job, but not as patient.

Hi doorman, appreciate the reply, the time delay is on the components, so card reader is programmed to keep relay open for 5 secs (internally to reader) and exit button is time delayed switch, (also 5 secs) no battery back up on system so fails when power cut, therfore no em exit break glass, these both work exactly as they should, hope that helps

Okay. If each release component has its own relock delay, we can take this road:

On the coil side of the relay, ONLY the two cores from the system should be used. I think it is established somewhere in this discussion that pair works correctly.

On the controlled side, in one continuous (series) circuit you should have:
Power Supply
Magnet
Relay
Release Button(s) terminals
Card Reader output relay terminals
Each control component should be terminated NC. Opening any contact will deenergize the magnet. This will isolate your lock system from the intercom system, which is desireable anyway.

Been a month and no more chatter. I guess we got to the end of it.

Gentlemen; you missed the part of a magnet strike this unit is energized continuously until the power is removed likely a bad switch to the relay or the relay was wired wrong or it has failed. does the reader activate the strike like it is suppose to, or has it failed also.Duke

reader works good, exit buttons work good, intercom works good other than the one unlock signal needed to activate the relay, thus denergising the magnet

Same will apply with or without a magnet door system, you basically just use the normally closed relay termials on the magnetic system, ie circuit stays closed until the card or prox reader is activated, opens the circuit.. Instead of connecting to a door strike it connects to the mag lock.

Yes but in reverse by killing the current not energizing the circuit you must also take into consideration the aux. exit device that is installed to break power in case of fire or emergency exit needs. there is a lot going on with these systems not common to just a strike, a mag system must include at least two means of egress,a REX/request to exit and or a mechanical break such as a panic bar with a switch to remove the power ,and or a push button/REX next to the door that is back lit in case of smoke in the room. these are national standards but as we all know some municipalities don't care about standard safety measure's, just their ability to be the AHJ/ Authority Having Jurisdiction.And believe you me some cities just don't care.Duke

Also you might find the problem in the phone system, and not in the control system these systems are developed to fit several systems and some times they just don't play well with each other for some god awful reason, until you find the problem part or parts then they will work without any problems until the next catastrophe decides to arise.Believe me I see a lot of these systems and have to figure out other peoples screw-ups and most of the time it is in poor wiring technique or misapplied parts not up to par for these systems. Usually trying to cut costs and it just don't work. Believe me when I say most problems are in the intergrator side of this equipment. when the intergrator says install this part, you install that part sometimes to the customer detriment. Just having done this 46 years and seen it all (well almost all).Duke.

The relay that is your problem is probably in your phone system. I work on these systems all the time and I find that some times the form c relay can't handle the in rush voltage and welds the contacts closed. Then it will not open the circuit, but all other venues of egress will still work. You don't have a low voltage situation you have an open circuit with a partial short someone probably forgot to install a diode across the circuit to keep flyback voltage from killing the relay.There are several systems that use either 12v or 24v. I myself have never seen an AC system, since you would have to rectify and filter to get the magnet to work, It does not make good sense to go to all that trouble to use AC when DC is easier. Duke

"You don't have a low voltage situation you have an open circuit with a partial short someone probably forgot to install a diode across the circuit to keep flyback voltage from killing the relay."

How have you divined from the torrent of information provided here that one of these

is not being used in this application? How many appliances are being energized with whatever power supply has been selected?

"I myself have never seen an AC system..." AC is very common in detention access control systems. We don't really know what this is.

have fitted a suppreser across positive and negative on magnet to prevent the strike backlash

From repairing these systems. He listed the manufacturer and part number. The system he is using is a dc system and the phone system is probably the source of the problem.

We have been told Bell 801. That is a specific handset, not a system. This information really does nothing to help us help him.

A Bell 801 handset can operate (according to the link) on 12VDC or 12VAC. No indication of amperage is give. If each handset individually closes (opens?) the contact controlling the door in question, I would even more strongly suspect line loss.

[M$ Sarcastic Font on]
However, you're prolly right: get some new phone equipment. That will solve it.
[M$ Sarcastic Font off]

have checked continuity on this particular core and have no line loss! bell 801 is a handst but it also comes in the system with phones controller etc

Most of these systems have circuit boards manufactured with a wave soldering process.and sometimes they will leave a fine thread short that is so fine you can't find it without a magnification process not very doable in the field. But very tedious to diagnose and enough to drive you nuts, and sometimes it is not a very long trip after having done the install and then find a problem.Duke