Tempo 521A Instructions page 10

Two-Step Solenoid Valve Locating Process
Solenoid valves can easily be located provided all the wires leading to them are
intact and the solenoid itself is still good.
Step 1. Start at the clock. Connect the red transmitter lead to the station wire
leading to the subject valve, and connect the black lead to earth ground. Turn the
transmitter on, adjust the output to the highest level, assemble the receiver, locate
the path, and start tracing the wire following the null. The null will be present until
you pass over a solenoid valve, and then the signal will become extremely strong.
Mark this spot. Check around this hot spot for a null leaving the area. If the null
continues, follow it and mark any additional hot spots. (Refer to Figure 6.) If only
one hot spot or valve is located, it will be the valve in question.
Step 2. If more than one hot spot is found, mark them and return to the transmitter
and turn it off. Lift the black lead from the ground stake and connect it to the
common wire. Turn the transmitter on, set the selector knob to the highest reading,
and return to the first hot spot with the receiver. Touch the tip of the receiver
antenna to the ground in the center of the first hot spot and set the sensitivity
knob to read near mid-scale. Now go to the second spot and without touching the
sensitivity knob, check the strength of the signal at each hot spot and determine
which, out of all of them, is the strongest signal. This is the valve for the station wire
you are connected to.
Receiver
Receiver
Meter
Signal Intensity
Solenoid
Pipe
Figure 6 – Locating Broken Wire End
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