Intercom buzzer way too loud

[Palo]

My Urmet 1133 door opener buzzer is way too loud and I have a heart attack every time it sounds.
The buzzer tone comes from the handset speaker, not from the base.
I don't see any indication on the wall board of a switch or jumper for the volume.
According to a manual I found online, the connector “CA” is for the buzzer.
There is no volume control, could I place a resistor in the CA wire that would reduce the volume of the buzzer tone? what Ohmage would be adequate?
Is that a good solution? I want to reduce only the volume of the buzzer not the voice volume.
I’ve attached the schematic and a photo of the unit.
They all seem to be double wires. Neubie question: Does it matter on which of the two "CA" white wires I sodder the resistor?
Thanks

 

[feynman]

Going by the circuit diagram, you can put a resistor in series at the CA connection, and that will only affect the buzzer volume.

Not knowing the impedance of the door phone speaker, it is hard to suggest a value. The impedance could be between 8 and 600 Ohms. I would try a 250 Ohms resistor or thereabouts. Or get a variable 1,000 Ohm potentiometer and adjust to taste.

I can't see why there are two CA wires, - maybe there is another remote buzzer? - but put the resistor between the connector block and both the wires.

Solder, not sodder !! (Sol - der. Some folk pronounce it incorrectly).

 

[Palo]

Thank you for your reply.
I checked the speaker and it reads 45 ohms 0.2w stamped on the back.
Would 250 ohms still ok? Or may as well get the potentiometer and be able to adjust the volume, it's a good idea.
Thanks again!

 

[feynman]

Huh, you can't sleep either ?! Oh just noticed your flag, you are probably 7 hours behind me.

A 45 Ohm resistor might halve the volume, but it might not vary linearly with voltage, so I would go for something like a 250 Ohm pot and adjust to taste.

 

[Palo]

Thanks. I'm in the Pacific Coast in Canada, its 10pm ...
Sorry if I kept you awake, almost time for morning coffee for you anyway, haha
Take care

 

[feynman]

No problem at all, you didn't - I have a cold coming on and couldn't sleep anyway

Been to Calgary, Whistler, (some of the best slopes I have skied), and Vancouver; all lovely. And Toronto, ditto. I have relatives near Halifax, NS.

I am sure you know how to wire a potentiometer, but if not; wire to the centre terminal and either one of the outer two, to give a variable resistance.

 

[feynman]

Any luck with this yet Palo ?