I am trying to find out how to read voltage from the circuit board on my 2003 Sweetwater Cayman. My ozonator is inop, I suspect a burnt out bulb, but wanted to double check before I order a new bulb. i tried reading voltage at the 240vac setting. I read 0 volts. Is there a specific sequence to read this? Maybe the ozonator wasn’t supposed to be on at the time I read voltage.