acet door entry system whining at night

[nwpattesting]

Hi, I have an old acet door entry system, buzzer and handset for 3 flats, not sure what model pic attached.

 

One of the flats says he gets a whining noise some nights, and goes to the box and hears a whine from that too.

Ive just had a fire alarm fitted, but I think he had it before that ?

 

Can anyone please help ?

thanks

[james.wilson]

Mic levels too high and feedback. Plus is the on hook switch broke / need adjusting? 

[nwpattesting]

Thanks Ill check that

[PeterJames]

Also check that all handsets are seated correctly, feedback is often caused if someone hasnt replaced their handset properly 

[nwpattesting]

Thanks for your help Peter will do

[nwpattesting]

I checked but cant see any volume adjustment on the mic.

So I guess the problem is the handset, not gained access to check that yet. 

[james.wilson]

29 minutes ago, nwpattesting said:

I checked but cant see any volume adjustment on the mic.

where did you look?

[al-yeti]

32 minutes ago, nwpattesting said:

I checked but cant see any volume adjustment on the mic.

So I guess the problem is the handset, not gained access to check that yet. 

Normally two pots I thought

[GaryO]

As it’s happening at night, I wonder if one of the users is leaving the handset off the hook (thinking it won’t disturb them)? If they leave it flat in a surface you are likely to get feedback from that.