How To Test A Coil Diode - Genie S-65 Service And Repair Manual

September 2016
How to T est a Coil Di ode

How to Test a Coil Diode

Genie incorporates spike suppressing diodes in all
of its directional valve coils except proportional
valves and those coils with a metal case. Properly
functioning coil diodes protect the electrical circuit
by suppressing voltage spikes. Voltage spikes
naturally occur within a function circuit following the
interruption of electrical current to a coil. Faulty
diodes can fail to protect the electrical system,
resulting in a tripped circuit breaker or component
damage.
Electrocution/burn hazard.
Contact with electrically charged
circuits could result in death or
serious injury. Remove all rings,
watches and other jewelry.
1 Test the coil for resistance. Refer to, How to
Test a Coil.
2 Connect a 10Ω resistor to the negative
terminal of a known good 9V DC battery.
Connect the other end of the resistor to a
terminal on the coil.
Resistor, 10Ω
Genie part number
Note: The battery should read 9V DC or more when
measured across the terminals.
Part No. 1268492 S-60 • S-65 • S-60 TRAX • S-65 TRAX • S-60 HC • S-60X • S-60XC
1 multimeter
2 9V DC battery
3 10Ω resistor
4 coil
Note: Dotted lines in illustration indicate a reversed
connection as specified in step 6.
3 Set a multimeter to read DC current.
Note: The multimeter, when set to read DC current,
should be capable of reading up to 800 mA.
4 Connect the negative lead to the other
terminal on the coil.
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Note: If testing a single-terminal coil, connect the
negative lead to the internal metallic ring at either
end of the coil.
5 Momentarily connect the positive lead from
the multimeter to the positive terminal on the
9V DC battery. Note and record the current
reading.
6 At the battery or coil terminals, reverse the
connections. Note and record the current
reading.
Result: Both current readings are greater than
0 mA and are different by a minimum of 20%.
The coil is good.
Result: If one or both of the current readings
are 0 mA, or if the two current readings do not
differ by a minimum of 20%, the coil and/or its
internal diode are faulty and the coil should be
replaced
Service and Repair Manual
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