Genie GTH-1048 Service Manual page 132

March 2015
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.
Electrocution 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 7-8, 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.
Note: The battery should read 9V DC or more
when measured across the terminals.
Resistor, 10Ω Ω Ω Ω Ω
Genie part number
3 Set a multimeter to read DC amperage.
Note: The multimeter, when set to read DC
amperage, should be capable of reading up to
800 mA.
Part No. 123701
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.
COIL
d
c
c
5 Momentarily connect the positive lead from the
27287
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.
GTH-1048 • GTH-1056
Section 4 • Repair Procedures
MANIFOLDS
-
10 W 9V
BATTERY
RESISTOR
-
a multimeter
b 9V DC battery
c 10Ω resistor
d coil
Note: Dotted lines in illustration indicate a
reversed connection as specified in step 6
a
MULTI
METER
b
b
4 - 63