Blank Screen on the FO ND DU

TASK 31-63-82-810-836-A
Blank Screen on the FO ND DU

1. Possible Causes

2. Job Set-up Information
A. Referenced Information

REFERENCE	DESIGNATION
AMM 31-60-00-860-001	EIS Start Procedure
AMM 31-60-00-860-002	EIS Stop Procedure
ASM 316102
AMM 31-63-22-000-001	Removal of the Display Unit
AMM 31-63-22-400-001	Installation of the Display Unit
ASM 316802

3. Fault Confirmation
Subtask 31-63-82-860-093-A ** ON A/C NOT FOR ALL

A. Job Set-up
(1) Do the EIS start procedure AMM 31-60-00-860-001.

4. Fault Isolation
Subtask 31-63-82-810-109-A ** ON A/C NOT FOR ALL

A. If the operational image is shown on the FO ND DU:

Subtask 31-63-82-810-110-A ** ON A/C NOT FOR ALL

B. If a maintenance message is shown on a black screen

Subtask 31-63-82-810-111-A ** ON A/C NOT FOR ALL

C. If a blank screen (screen completely black) is shown on the FO ND DU:

(1) If the fault continues:
(a) Do a check for 115VAC at pin AA-79 of the FO ND DU ASM 316102.
1 If there is no 115VAC:

check the wiring from the ND FO SPLY-C/B (12WT2) to the FO ND-DU(3WT2) pin AA-79.

a if there is no continuity:

b If there is continuity:

2 If there is 115VAC:

a If there is no ground signal:

check and repair the wiring from the FO ND-DU pin AA-77 to the the ground terminal.

b If there is a ground signal:

do a check for 28VDC at the FO ND-DU pin AA-81
. if there is no 28VDC, check and repair the wiring from the FO ND-DU pin AA-81 to the FO ND-SWTG C/B (23WT2)
. if there is 28VDC, replace the C/B-EIS/ND/F/O/SWTG [23WT2] .

(2) If the fault continues:

(a) If there is a ground signal:

1 If there is no ground signal:

check and repair the wiring from the FO ND-POT (8WT2) pin 8 to the FO ND-DU (3WT2) pin AA-75.

2 If there is a ground signal:

5. Close-up
Subtask 31-63-82-860-107-A ** ON A/C NOT FOR ALL

A. CLose-up

[Rev.8 from Aug 2018] 2026.04.04 04:31:16 UTC