Genie GS-3384 Service Manual page 165

September 2005
REV D
How to Test a Coil Diode
Genie incorporates spike suppressing diodes in all
of its valve 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 7-12, 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.
The battery should read 9V DC or
more when measured across the
terminals.
Resistor, 10W
Genie part number
3 Set a multimeter to read DC ampreage.
The multimeter, when set to read
DC amperage, should be capable
of reading up to 800 mA.
4 Connect the negative lead to the other terminal
on the coil.
If testing a single-terminal coil,
connect the negative lead to the
internal metallic ring at either end
of the coil.
Part No. 82259
COIL
d
c
c
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.
27287
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.
GS-3384
Section 4 • Repair Procedures
-
W
10 9V
BATTERY
RESISTOR
-
a multimeter
b diode
c 9V battery
d 10Ω resistor
e coil
Note: Dotted lines in illustration indicate a
reversed connection as specified in
step 6
MANIFOLDS
a
MULTI
METER
b
b
4 - 81