Bell box without strobe? Or what?

[henrylaw]

Just replaced the control unit from an ancient alarm installation, keeping the existing wiring because it would be a b***er to replace. The external bell is wired up rather eccentrically, with a four-core cable of which red/black drives the siren and yellow/blue provides tamper indication via a simple microswitch. Just to make matters worse, there's a panic button on the landing which is simply wired in series with the tamper switch on the bell box; in other words panic is signalled to the tamper terminals on the control unit.

That would be all right, but the external sounder doesn't sound. Might be the box, might be the cable and I'm hoping it's the former (for reasons given above). So I'm going to try a new bell box. But there are only four cores in the cable so I can't see how I'd control a strobe.

Questions: (1) can anyone point me to a bell box without a strobe? I've searched for ages without finding one. Or (2) can someone suggest how I might use four cores and a "normal" bellbox, with a strobe in it. Householder doesn't mind if the strobe is disabled, since there's none there just now.

 

[sparkymarka]

A ..... Don't connect the strobe - trip in the bell box ( no strobe)
B ...... Link the strobe -trip to the bell - trip in the bell box ( strobe runs with bell )
I suggest you fit a Pyronix delta bell as the strobe is led ( low current )

 

[henrylaw]

Excellent; I wondered if something like that would work. An LED strobe, eh? How technology marches on.

I'm going to test the cable tomorrow: a tedious bout of shinning up the ladder to connect pairs of wires together, and then running back inside to put a meter across the other ends.

 

[EightyTwo]

Shin up the ladder and connect all four cores together. Go to the panel end and check continuity between red-black, red-blue, red-yellow, black-blue, black-yellow, blue-yellow. Then open circuit all four cores and do the same again. If everything is shorted on the first test and open on the second, your cable is good!

You could do the second test at the top of the ladder, if you're confident. Then you can put it back together before coming down - only two trips up the ladder!

 

[henrylaw]

Good thinking. I did the n(n-1)/2 calculation, like a theoretician, and totally missed the practical application!