I'm trying to mend the intercom in a friend's flat. There are three flats and my friend can hear what visitors say, but the visitors can't hear what she says. It's the same for each flat.
It seems that the speaker is faulty in the unit outside with the buttons on it.
I have removed the speaker and it's 70mm across and says 0.5 watts and 16 ohms. It's a mylar cone one.
Will 8 ohm and 1.5 watts be ok as it's the nearest I can seem to find online?
It probably will. If not the intercom amp will die.
NT
I suppose that the speaker has to be the prime suspect, but there are lots of things which it *could* be. Can you test the speaker by removing it and connecting it to another sound source (HiFi system, etc.)?
If it isn't the speaker, it could be a wiring problem.
It could *even* be a problem with all 3 of the handsets in the flats. If they're like the ones in my holiday flat[1], the receiver rest operates two springy contacts[2] - one for transmit and one for receive - and if these get dirty (or even a bit oxidised) it's quite common for one or other function not to work. [If you part dismantle the handset, you can unhook the springy contacts and clean them with the likes of a manicure-type emery board].
[1]- which is the common return for earpiece and microphone - when the receiver is off-hook
A speaker like that is easy to check. Examine for physical damage then 'wipe' a 1.5v cell across the terminals. You should see the cone move and hear a click.
Odd. because the speaker is also the microphone in most door phones.
In all the ones that I've fitted there has been a separate electret mic'
I think it boils down to Murmansk having to do a bit of testing to be sure.
Could the fault be in another flat? The system thinking that that flat is trying to speak out and is thus muting the speaker and so stopping it working for all the others too?
Have fun, especially with trying to get assistance from the other flat owners :-)
Thanks for those responses.
I contacted a company that specialises in mending intercoms and is based in London - intercomsrus.com - they said it would be the speaker and that I'd be best not ordering one from them as their supplier charges a ridiculous £38. They suggested finding one myself for a few pounds.I thought this wa s very helpful and honest.
The intercom unit at the front door does indeed appear to have a separate m icrophone.
I've tried wiping a battery over the speaker terminals and the speaker is s ilent so it sounds like that's the culprit.
in London - intercomsrus.com - they said it would be the speaker and that I 'd be best not ordering one from them as their supplier charges a ridiculou s £38. They suggested finding one myself for a few pounds.I thought this was very helpful and honest.
silent so it sounds like that's the culprit.
It is. £38!! Any old 15 or 16 ohm speaker than physically fits should do.
NT
car boot sale and get 30 old tranny radios for a 5ver
They're usually more like 40 ohm. So might be a bit too quiet. And may not like the damp. Hence the original being Mylar.
I used to reinforce/waterproof the cones for some uses. Its important to us e something that remains to some degree flexible, humbrol enamels would bre ak up when the thing endstopped, causing ongoing distortion. ISTR banana oi l being good, but it was a long time ago. Whether the card & glue in the vo icecoil will survive damp I cant be certain, but I have used basic speakers in damp places and got away with it.
NT
If the coil is intact, it may be possible to free it up with some cleaning.
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