TM 9-4120-357-14
NOTE
The continuity test does not necessarily indicate performance of the circuit
breaker under load. If the circuit breaker continues to trip after passing the
continuity test, substitute a circuit breaker known to be good, and check
operation in normal use.
(3) Armature relays (K1, K2, K7, K8, K9). Using an
ohmmeter or
continuity tester, and a
source of
24-28
volt dc power, check continuity of relays (17, 18, 19, 21 and 22) as follows:
(a) Apply 24-28 volt dc power to terminals X1-X2 to actuate relay.
(b) Check continuity of
pairs A1-A2, B1-B2 and C1-C2. Continuity should exist.
(c) Check continuity from each terminal to ground, with power disconnected from terminals X1-X2. Continu-
ity should not exist.
(d) Replace relay if continuity check indicates malfunction.
(4) Time delay relay (K6). Test the time delay relay (9, figure 4-10) with an
ohmmeter or
continuity tester, a
source of 24-28 volt dc power, and a watch or clock on which seconds can be read. Proceed as follows:
(a) With the time delay relay disconnected, check continuity between terminals 2
and 4.
Continuity should
be indicated.
(b) Connect the test probes to terminals 2 and 3. While monitoring the time, apply a source of 24-28 volt dc
power to the dc terminals of the time delay relay (positive (+) to positive, and negative (-) to negative).
(c) Continuity should be indicated after a delay between 19 and 31 seconds. If the delay is not within limits,
replace the time delay relay.
(5) Transformer. Test the transformer (23, figure 4-3) using a
volt-ohmmeter or
multimeter and a
source of
208-volt power. Proceed as follows:
(a) With the meter set on
ohms, and the transformer disconnected. Check continuity of
the primary (input)
windings. Continuity should be indicated.
(b) Check for continuity between on
input terminal and casing or
common ground. Continuity should not
exist. If it does replace the transformer.
(c) Check continuity of
secondary (output) windings. Continuity should be
indicated.
(d) Check for continuity between one output terminal and casing or
common ground. Continuity should not
exist. If it does, replace the transformer.
(e) Connect the primary leads of
the transformer to a
source of
208-volt, 60 hz
power, and check output at
the secondary leads with an ac voltmeter. Secondary voltage should be 28-30 volts dc. If out of limits, replace trans-
former.
(6) Terminal Boards. (See 7, 8,
figure 4-10) Visually inspect terminal boards for obvious damage and evidence
of electrical burns. If damaged, replace.
(7) Electrical Receptacles. Inspect electrical receptacles for damaged shell, bent or
missing pins, broken wa-
fers and broken terminals. Replace if damaged.
(8) Filter and Rectifier Assembly. (Figure 4-2.) Remove four screws (6) and lock washers (5), and carefully
remove end cap (4). Inspect for loose internal connections, broken wires or other damage.
(9) RFI Filters. Disconnect leads from rectifier (8). Using an
ohmmeter, check continuity between leads of
each
filter. If no continuity is shown, replace the filter.
(10) Rectifier. With rectifier (8) Disconnected from filters, connect a source of 28-volt ac power to the ac termi-
nals. Check dc terminals with a dc voltmeter. Voltage should read 24+5 volts, dc. If output voltage is less than speci-
fied, replace the rectifier.
d. Installation. Install the junction box in the air conditioner in accordance with the following steps:
(1) Place the junction box in approximate position in the air conditioner, and insert the core of the circuit breaker
control cable through the hole in top of the actuating arm (15, figure 4-3.)
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