Loss of the HFDR1 Data Detected by the ATSU

TASK 46-21-00-810-845-A
Loss of the HFDR1 Data Detected by the ATSU

1. Possible Causes

XCVR-HF, 1 [3RE1]
ATSU [1TX1]
wiring of the HF1 OUTPUT BUS

2. Job Set-up Information
A. Referenced Information

REFERENCE	DESIGNATION
AMM 23-11-33-000-001	Removal of the HF Transceiver
AMM 23-11-33-400-001	Installation of the HF Transceiver
AMM 46-21-00-740-001	BITE Test of the ATIMS
ASM 462105
AMM 46-21-34-000-001	Removal of the Air Traffic Service Unit (ATSU)
AMM 46-21-34-400-001	Installation of the Air Traffic Service Unit (ATSU)

3. Fault Confirmation
Subtask 46-21-00-865-052-A

A. Table of the circuit breakers used in this procedure:

PANEL	DESIGNATION	FIN	LOCATION
** ON A/C NOT FOR ALL
49VU	COM HF1	1RE1	HA14
** ON A/C ALL
121VU	ATSU 1	3TX1	L16
121VU	ATSU 1/SWTG	5TX1	L15

Subtask 46-21-00-740-136-A

B. Test
(1) Do the BITE test of the ATIMS AMM 46-21-00-740-001.

4. Fault Isolation
Subtask 46-21-00-810-095-A

A. If the test gives the maintenance message HFDR1(3RE1)/ATSU1(1TX1):
(1) Make sure that the circuit breakers 1RE1, 3TX1 and 5TX1 are closed.
(a) If the fault continues:

open and close the circuit breaker 1RE1 to reset the HFDR1.

1 If the fault continues:

open and close the circuit breakers 3TX1 and 5TX1 to reset the ATSU.

(2) If the fault continues:

replace the XCVR-HF, 1 [3RE1] AMM 23-11-33-000-001 and AMM 23-11-33-400-001.

(a) If the fault continues:

replace the ATSU [1TX1] AMM 46-21-34-000-001 and AMM 46-21-34-400-001.

1 If the fault continues:

remove the HFDR1 and the ATSU
do a check and repair the wiring of the HF1 OUTPUT BUS : between pins AA/9C,9D of the HFDR1 and pins AA/4E,4F of the ATSU ASM 462105
install the HFDR1 and the ATSU.

Subtask 46-21-00-740-137-A

B. Do the test given in Para. 3.

[Rev.8 from Aug 2018] 2026.04.04 04:34:21 UTC