Table 5-4. Troubleshooting - Continued

TM 9-4931-378-13&P

21. NO CONTINUITY OR OUT OF TOLERANCE RESISTANCE BETWEEN ONE OR MORE CHECK POINTS, DESIG-

NATED IN CHASSIS WIRING CHECK.

Step 1. Perform continuity check of appropriate wiring. (See paragraph 5-14 and figure FO-1.)

Repair wiring as necessary.

Table 5-4. Troubleshootting Continued

Malfunction

Test or Inspection

Corrective Action

22. CIRCUIT BREAKERCBI FAILS TO LATCH IN ON.

Step 1. Check bench 115 Vac power.

Correct as necessary.

Step 2. Perform continuity/short circuit checks on ac input power lines. (See paragraph 5-14 and figure FO-1.)

Repair wiring as necessary.

Step 3. Check circuit breaker CB1.

Replace circuit breaker CB1.

23. 115 VAC LAMP FAILS TO ILLUMINATE WHEN CB1 IS ON.

Step 1. Check 115 VAC lamp.

Replace 115 VAC lamp.

Step 2. With S11 set to 115 VAC, confirm 115 Vac present at TP9 and TP10. If present, proceed to step 7.

If absent, proceed to step 3.

Step 3. Check circuit breaker CB1.

Replace circuit breaker CB1.

Step 4. Check filter FL1.

If filter is defective, send test set to higher maintenance for repair.

Step 5. Check filter FL2.

If filter is defective, send test set to higher maintenance for repair.

Step 6. Check diode CRI.

Replace diode CR1.

Step 7. Check resistor R1.

Replace resistor R1.

Step 8. Perform continuity check on ac input power lines. (See paragraph 5-14 and figure FO-1.)

Repair wiring as necessary.

24. NO DISPLAY ON DATA WORD READOUT (DS12) WHEN 115 VAC IS ON.

Step 1. With S11 set to 5V, confirm that +5 Vdc is present between TP9 and TP10. If present, proceed to step 4; if

not, proceed to step 2.

Step 2. Confirm that 115 Vac is present at power supply PS1 input terminals. (See figures 5-9 and FO-1. )

Repair wiring as necessary.

Step 3. Confirm that +5 Vdc is present at PS1 output terminals. (See figures 5-9 and FO-1.)

Replace power supply PS1.

Step 4. Remove CCA 1A1. Confirm +5 Vdc present at motherboard connector XA1, pins 25, 26, 75, 76. (See

figure 5-8.)

If present, install replacement CCA 1A1; if not, reinstall CCA 1A1 and proceed to step 5.

Step 5. Remove CCA 1A2. Confirm +5 Vdc present at motherboard connector XA2, pins 25, 26, 75, 76. (See

figure 5-8.) Reinstall CCA 1A2.

Step 6. Disconnect connectors P2 and P3 (figure 5-9) and confirm +5 Vdc present at connectors P2 and P3

between all +5 Vdc and 0 Vdc pins. (See paragraph 5-14 and figure FO-1.) Reconnect connectors

P2 and P3 after signal tracing.

If voltage is present, send test set to higher maintenance for repair; if not, repair wiring as necessary.

Step 7. Confirm +5 Vdc present at DS12 connectors P1, P2, and P3. (See paragraph 5-14 and figure FO-1.)

Repair wiring as necessary.

Step 8. Replace DATA WD readout DS12.

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