Genie GS-2669 RT Service Manual page 136

Section 4 • Repair Procedures
MANIFOLDS
How to Test a Coil Diode
Genie incorporates spike suppressing diodes in
many 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/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 9-6, 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 current.
Note: The multimeter, when set to read DC
current, should be capable of reading up to 800
mA.
4 - 66
27287
GS-2669 RT • GS-3369 RT • GS-4069 RT
COIL
d
c
1W
RESISTOR
c
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
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 DC
battery. Note the current reading.
6 At the battery or coil terminals, reverse the
connections. Note 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.
November 2014
MULTI
METER
-
+
9V
BATTERY
+
-
Part No. 229753
a
b
b