TM 9-4120-407-14
b. Testing.
(1) Rectifier (CR1) Testing.
(a) Using a multimeter set to measure resistance, perform the following checks on rectifier (1)
1 Connect black (negative) lead to terminal 4 and red (positive) lead in turn to terminals 1
and 2. A low resistance reading should be indicated.
2 Connect red (positive) lead to terminal 4 and black (negative) lead in turn to terminals 1
and 2. An open circuit should be indicated.
3 Connect red (positive) lead to terminal 3 and black (negative) lead in turn to terminals 1
and 2. A short circuit should be indicated.
4 Connect black (negative) lead to terminal 3 and red (positive) lead in turn to terminals 1
and 2. An open circuit should be indicated.
(b) Replace rectifier (1) if defective.
(2) Rectifier (CR4) Testing.
(a) Using a multimeter set to measure resistance, perform the following checks on rectifier (1)
1 Connect black (negative) lead to terminal 2 and red (positive) lead in turn to terminals 1
and 3. A low resistance reading should be indicated.
2 Connect red (positive) lead to terminal 2 and black (negative) lead in turn to terminals 1
and 3. An open circuit should be indicated.
3 Connect red (positive) lead to terminal 4 and black (negative) lead in turn to terminals 1
and 3. A short circuit should be indicated.
4 Connect black (negative) lead to terminal 4 and red (positive) lead in turn to terminals 1
and 3. An open circuit should be indicated.
NOTE
Rectifier (CR4) will fail if surge arrestor (SA1) is defective. It is
advisable to replace the surge arrestor as a precautionary measure
any time the rectifier is found to be defective.
(b) Replace rectifier (1) if defective.
(3) Capacitor (C1) Testing. Using a capacitance meter set to measure capacitance in pico Farads,
measure between capacitor (2) Figure 3-45 terminal leads. A capacitance of between 9,000 and
11,000 pF should be indicated. Replace capacitor if defective.
(4) Capacitor (C2) Testing. Using a capacitance meter set to measure capacitance in micro Farads,
measure between capacitor (3) Figure 3-45 terminal leads. A capacitance of between 110 and 130 F
should be indicated. Replace capacitor if defective.
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