ARR Series Three Phase, Six Pulse SCR Charger
Corrective Maintenance
RS-420, Rev. 7
5-3
5.4
SPECIFIC PROBLEM CHART
PROBLEM
POSSIBLE CAUSES
SOLUTION
A. No Voltage (E) at power
transformer secondary
(sec.)
1. Open AC circuit breaker.
2. Open winding (s) on power
transformer
a. Close AC circuit breaker.
b. Replace power transformer.
B. Incorrect E sec.
1. Incorrect AC input for the charger
connections
a. Refer to Connections #4 on page 4.
C. Correct E sec. but no E sec.
on output of Anode fuses.
1. Open Anode fuses.
a. Replace Anode fuse, if it blows again,
see E., 1., a. below.
D. E sec. on output of Anode
fuses, but still no DC
output from charger.
1. Open control fuse (to check control
fuse, look for proper voltage at
auxiliary transformer E AFX
primary.)
2. Primary winding of auxiliary voltage
transformer is shorted (indicated by a
blown control fuse.)
3. Current Limit Potentiometer open.
4. Defective Printed Circuit Control
Cards.
a. Replace control fuse and check
secondary voltage of AXF (Auxiliary
Transformer). See instruction 5.4.4.
a. Replace auxiliary transformer.
a. See instruction 5.4.6.
a. Replace printed cards or see instruction
5.4.6.
E. Loss of output Voltage and
Current, or Low Output
Current.
1. Anode Fuse (s) open. (This can be
caused by a high current surge.)
a. Replace with equivalent fuse. (See part
list.) If Anode fuse blows again check
for:
1. shorted diodes & SCR’s (See
instruction 5.4.2).
2. defective control boards (See
instruction 5.4.6).
2. Control Fuse open.
a. Replace with similar rated fuse (See
parts list). If fuse blows again, check
the primary of the auxiliary
transformer (AXF) with a voltmeter
(refer to Voltage Checkpoint Chart).
3. Auxiliary Voltage transformer
winding (s) open.
a. See instruction 5.4.4.
4. Open SCR’s Anode to Cathode and/or
Diodes.
5. Open Current Limit Resistor
a. See instruction 5.4.2.
a. Replace
6. Shorted gates or open gates.
a. See instruction 5.4.2.
7. Loose or broken connections
a. Check for signs of overheating or
corrosion, and repair connections.
8. Printed circuit boards defective.
a. Replace or see 5.4.6.
