Terex Genie Z-33/18, Service And Repair Manual

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3-40 Z ® -33/18 Part No. 1268514GT
January 2020 Section 3 • Repair Procedures
How to Test a Coil Diode
Genie incorporates spike suppressing diodes in all
of its coils. 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.
WARNING
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. See 6-3, How to
Test a Coil .
2 Connect a 10
Ω
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. 10
Ω
Genie part number 27287
Note: The battery should read 9V DC or more
when measured across the terminals.
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.
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
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.
+
-
+
-
d
b
b
a
c
c
COIL
10
Ω
RESISTOR
9V
BATTERY
MULTI-
METER
a multimeter
b 9V DC battery
c 10
Ω resistor
d coil
Dotted lines in illustration indicate a
reversed connection as specified in step 6
MANIFOLDS