Door Entry System Fault

[Daljit]

Hi there

I have just bought a flat that has a very old door entry system that isn't working properly. The following functions work fine: buzzer rings when visitor arrives; visitors can hear me speak; i can let people enter the building; and privacy switch works. However, visitors can't hear my voice.

I had a look at a neighbour's entry phone which works perfectly and i found it had a small black box (about an inch square) with two wires in the casing. The box seemed to be added-on (perhaps as a result of a repair or modification) as is wasn't securly fastened. The two wires were hooked to the system.

Other than this box, the wiring in my phone is identical to my neighbour's.

I know this description is really vague, but does anyone have any suggestions what this little black box does, and more importantly, what it's called?

thanks

Daljit

[Owain]

I would suspect a broken wire or high resistance joint, or if it uses carbon transmitters (older BSTL / Bell System ones do) the capsule's gone phut.

Pass.

Any chance of any photos?

Owain

[Bob Eager]

Some internal battery died (carbon mic?) and they attached a supplementary external one?

[Keith]

In message , Daljit writes

Gonna run that past us again ......

[Daljit]

Oops,

I meant i can hear visitors, but they can't hear me! Well spotted, and thanks.

Daljit

[Daljit]

Oops! I meant i can hear visitors, but they can't hear me. Well spotted, and thanks.

Also - i think it might be a Bell system - i'll check tonight.

Daljit

[Keith]

OK, so, assuming the speaker in the flat unit doubles as a microphone when you press the 'speak' button, then the fault most probably lies in the mechanism that switches from 'speak' to 'listen' in the flat unit. I've no idea whether your system uses a mechanical switch, a relay, or electronic switching, but the fault could be as simple as a dirty contact in the button.

[Owain F Carter]

I would suspect a broken wire or high resistance joint, or if it uses carbon transmitters (older BSTL / Bell System ones do) the capsule's gone phut.

Another possibility if you have a mix of carbon/electret transmitters, if a handset with a carbon granule microphone is ?off the hook? and is preventing the electret microphone from operating. You will therefore need to find this (or indeed other handsets) and fix the problem. One way of detecting handsets that are ?off the hook? is to call each handset from the door ? you should get the sound of the buzzer coming out of the door speaker when the offending handset(s) is called.

Owain

[Owain]

If it's BSTL (Bell System) then they (used to?) use carbon transmitters and the capsules *do* die.

stock Bell stuff and are happy to despatch on credit card orders.

Owain