I did a bell test for the fist time in years. Not surprisingly, it didn't ring.

After tracing the correct cable/wiring, I decided to measure a few output voltages from the control panel. Here's what I found:

In Day mode: BEL = 0V, SCB = 0V

In BELL Test mode: BEL = 12V, SCB = 0V

I've done a continuity test on all wires and they're fine.

Are the o/p's what you would expect? What is SCB used for, because I get different readings when the Tamper switch is activated on the Bell Box, i.e. BEL = 0V, SCB = 5V?

The strobe works OK, so is it the control panel at fault or is a new Bell box the answer?

Hope you can help.....

In Day mode you should have:

0 Volts at Tamper Return (SCB T)

0 Volts at Tamper Feed (Hold -) (SCB A)

0 Volts at Trigger (Bell -)

12 Volts at 12V + Terminal (Bell +)

In Bell Test Mode, you should have as above but with 12 Volts at the Trigger Terminal.

Thanks for your help. It was the bell box at fault.