Operational Test of the Clock

TASK 31-21-00-710-002-A
Operational Test of the Clock

WARNING: MAKE SURE THAT ALL THE CIRCUITS IN MAINTENANCE ARE ISOLATED BEFORE YOU SUPPLY ELECTRICAL POWER TO THE AIRCRAFT. UNWANTED ELECTRICAL POWER CAN BE DANGEROUS.

ZONE: 210

1. Reason for the Job
To make sure that the clock and the standby power supply operate correctly.
2. Job Set-up Information
A. Work Zones and Access Panels

ZONE/ACCESS	ZONE DESCRIPTION
210	CKPT,FWD COMPT BHD TO FLT COMPT BULKHEAD

B. Referenced Information

REFERENCE	DESIGNATION
TASK 24-41-00-861-002-A	Energize the Aircraft Electrical Circuits from the External Power
TASK 24-41-00-861-002-A-01	Energize the Aircraft Electrical Circuits from the APU
TASK 24-41-00-861-002-A-02	Energize the Aircraft Electrical Circuits from Engine 1(2)
TASK 24-41-00-862-002-A	De-energize the Aircraft Electrical Circuits Supplied from the External Power
TASK 24-41-00-862-002-A-01	De-energize the Aircraft Electrical Circuits Supplied from the APU
TASK 24-41-00-862-002-A-02	De-energize the Aircraft Electrical Circuits Supplied from the Engine 1(2)
TASK 31-21-00-750-002-A	Procedure to Set the Clock

3. Job Set-up
Subtask 31-21-00-861-051-A

A. Energize the aircraft electrical circuits (Ref. AMM TASK 24-41-00-861-002)

Subtask 31-21-00-865-051-A

B. Make sure that this(these) circuit breaker(s) is(are) closed:

PANEL	DESIGNATION	FIN	LOCATION
** ON A/C ALL
49VU	CLOCK/NORM/SPLY	6FS	F11
121VU	CLOCK/STBY/SPLY	4FS	N02

4. Procedure
Subtask 31-21-00-710-050-B ** ON A/C NOT FOR ALL

A. Test

ACTION	RESULT
1.On the overhead panel, on the panel 25VU:	On the R center instrument panel 400VU, on the clock:
set the ANN LT switch to TEST.	the digital displays show 8s.
2.On the overhead panel, on the panel 25VU:
set the ANN LT switch to BRT.	the time comes into view.
3.On the clock:
push the CHR pushbutton switch.	the sweep hand starts. the numbers of the minutes come into view in the ET/CHR window.
after not many seconds, push the CHR pushbutton switch for a second time.	the sweep hand stops and the ET/CHR display is frozen.
push the CHR pushbutton switch for a third time.	the sweep hand goes back to the 60 position and the ET/CHR display is off.
4.On the overhead circuit breaker panel 49VU:
open the circuit breaker 6FS.	the digital displays go off.
5.Close the circuit breaker 6FS.	the time comes into view. if the time shown is not correct, set the clock (Ref. AMM TASK 31-21-00-750-002).

Subtask 31-21-00-710-050-C ** ON A/C NOT FOR ALL

A. Test

NOTE: Make sure that the time shown on the clock is correct.

NOTE: Make sure that the A/C batteries are not removed.

ACTION	RESULT
1.On the overhead panel, on the panel 25VU:	On the R center instrument panel 400VU, on the clock:
set the ANN LT switch to TEST.	the digital displays show 8s.
2.On the clock:
push the DATE pushbutton switch.	the numbers in the digital displays go from 0 to 9.
3.On the overhead panel, on the panel 25VU:
release the ANN LT switch from the TEST position, and release the DATE pushbutton switch.	the time comes into view.

5. Close-up
Subtask 31-21-00-860-050-A

A. Put the aircraft back to its initial configuration.
(1) De-energize the aircraft electrical circuits (Ref. AMM TASK 24-41-00-862-002).
(2) Make sure that the work area is clean and clear of tools and other items.

[Rev.10 from 2021] 2026.04.01 08:27:10 UTC