TM 11-5841-287-30
Table 3-2. Encoder and Data Link Control Troubleshooting-Continued
MALFUNCTION
TEST OR INSPECTION
CORRECTIVE ACTION
Step 8 Label, then disconnect, the three wires at blower connecting 2B1 to terminals 2E8, 2E9, and 2E10 Check if 2K1-A1 is still shorted to 2Kl-
B1
(a) To short circuit Proceed to step 9
(b) Shortcurcuit Proceed to step ll
Step 9 Check 2C1 for a short circuit (2E8 to 2E9)
(a) No short circuit Remove defective 2B 1 and replace with good blower Reconnect wires
(b) 2C1 short circuited Replace defective 2C1 Reconnect 2B1 Proceed to step 10
Step 10
Check for short circuit between 2K1-A1 and 2K1-B1
(a) No short circuit Fault was corrected with replacement of 2C1
(b) Stdl shorted Remove defective blower 2B1 Replace with good blower Reconnect wires
Step 11
With power OFF, unsolder 115 Vac leads to 2M1 and recheck for short circuit between 2K1-A1 and 2K1-B1 Repeat this procedure on
2PS1, 2PS2, and 2PS3 until short circuit between disappears Replace the short circuited component (the last one unsoldered) and
reconnect the others If all these components are disconnected and a short circuit still exists, replace 2K1
Step 12
Reconnect power cable to 2J2 Turn power ON Check for 115 Vac between K1-A2 and K1-B2
(a) Voltage absent Proceed to step 13
(b) Voltage present Proceed to step 15
Step 13
Turn power OFF Disconnect 2P4 from 2PL1 Turn power ON and check for 115 Vac across 2FL1J1-5 to FL1J1-4 (fig 3-6)
(a) Voltage absent Turn power OFF Remove and repair 2FL1 Ac circult s defective
(b) 115Vacpresent Proceedtostepl4
Step 14
Check ac wiring from 2FL1 to 2K1
(a) Turn power OFF Replace any defective wiring
(b) No defective wiring Turn power OFF Replace 2K1
Step 15
Disconnect power cable from 2J2 Return to step 7
6.
ENCODER FAULT INDICATOR ON DATA LINK CONTROL ILLUMINATES IMMEDIATELY AFTER PLACING POWER SWITCH IN STBY
POSITION AND ENCODER BLOWER OPERATES
Step 1 Measure dc voltage at 2A13J1-5
(a) 3 5 + 1 5V present Perform step 2
(b) 0 + 0 5V present Proceed to step 3
Step 2 Turn power OFF Remove 2A16 Reapply power and measure the voltage at 2A13J1-7
(a) 0 + 0 5V present Turn power OFF Replace 2A16
(b) Any other voltage present Turn power OFF Replace defective 2A13
Step 3 Measure dc voltage at 2A13J1-3
(a) 10 + 1 Vdc(normal) Proceed to step 4
(b) Any other voltage Turn power OFF Replace defective 2A13
Step 4 Measure dc voltage at 2A13J1-1
(a) + 12 + 0 6 Vdc (normal) Proceed to step 13
(b) Any other voltages Proceed to step 5
(a) + 12 0 6 Vdc Proceed to step 6
(b) Any other voltage Proceed to step 8
Step 6 Check for + 12 + 0 6 Vdc at 2A19XA13-2
(a) + 12 + 0 6 Vdc Turn power OFF Remove 2A13 and check continuity between 2A19XA13-54 and 2A19XA13-50 If open, replace 2A19 If not,
replace 2A13
(b) Any other voltage Proceed to step 7
Step 7 Turn power OFF Disconnect 2P3 from 2A19J3 Turn power ON Measure dc voltage at 2P3-A2
(a) + 12 + 0 6 Vdc Turn power OFF Replace electrical connector assembly 2A19
(b) Any other voltage Turn power OFF Repair wiring from 2PS3-3 to 2P3-A2 or from 2PS3-4 to ground Reconnect 2P3 to 2A19J3
Step 8 Turn power OFF Pull out all circuit cards far enough to break contact with connectors on electrical connector assembly 2A19 Turn power
ON Adjust 2PS3 overvoltage protectors 2U3 and 2U4 (para 3-21)
NOTE
Make only those adjustments pertaining to 2PS3, 2U3, and 2U4.
(a) Adjustment successful Proceed to step 9
(b) Adjustment unsuccessful Proceed to step 11
Step9 Turn power OFF Insert circuit cards in connectors Turn power ON
(a) Encoder fault lamp no longer illuminates with power switch m STBY Fault is corrected
(b) Encoder fault lamp still lights immediately In STBY Proceed to step 10
Step 10
Either power supply 2PS3 is unable to deliver rated load or a shorted circuit card Is overloading supply Turn power OFF Check each
circuit card for short circuits per para 3-27 through 3-37 to point where MODE/POWER SHORT lamp Is checked (Full functional test of
each card is not necessary ) Replace any defective cards
Step 11
Isolate + 12V supply 2PS3 by labeling and disconnecting wires from terminal 3, 4, and 5 Turn power ON Adjust ADJ pot on 2PS3 for +
12 + 0 1V (2PS3-3 to 2PS3-4 which is ground)
3-6
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