I am troubleshooting a fire alarm system that has strobe circuits. The strobes have a positive and negative terminal. Putting my multimeter across the terminals (+ to +, - to -) I read 79K ohms. The other way (+ to -, - to +) I read nothing. All very normal and typical of what I would expect a fire alarm strobe to do.
An example circuit of 2 strobes are wired in parallel and at the end of the circuit there is a 24K ohm resistor. Reading the circuit in what we would consider standby or monitoring mode (+ to -, - to +) I read the 24K ohm resister perfectly. However in active mode (+ to +, - to -) instead of reading something like 15K I am reading 22K.
Doing the math 1/14.929 = 1/79 + 1/79 + 1/24
I realize I am missing something amazingly obvious as the system works, strobes do their thing, panels are happily monitoring the strobes, but I do not understand where I have gone astray.
Thank you for your time and kind attention,
EEjack
An example circuit of 2 strobes are wired in parallel and at the end of the circuit there is a 24K ohm resistor. Reading the circuit in what we would consider standby or monitoring mode (+ to -, - to +) I read the 24K ohm resister perfectly. However in active mode (+ to +, - to -) instead of reading something like 15K I am reading 22K.
Doing the math 1/14.929 = 1/79 + 1/79 + 1/24
I realize I am missing something amazingly obvious as the system works, strobes do their thing, panels are happily monitoring the strobes, but I do not understand where I have gone astray.
Thank you for your time and kind attention,
EEjack