Message Name:

AUDIO PANEL 2 MALFUNCTIONS

One or more audio panel functions do not operate correctly.

• Audio Panel 2 (A9)
• Secondary Power Distribution Assembly (SPDA) 1 (A13)
• Secondary Power Distribution Assembly (SPDA) 4 (A16)
• Associated Wiring

Advisory Wire/Service Bulletin: None

Forum Articles/Infoservice/Newsletter: None

1. Swap Audio Panel 2 with Audio Panel 1. Is the fault still present?

   1. If NO, go to step 12.
   2. If YES, continue with next step.

2. Disconnect Audio Panel 2 connector (A9P1) and perform a continuity check as follows:

   Audio Panel 2	Expected Result	Result
   A9P1-V	28 VDC
   A9P1-U	28 VDC
   A9P1-M	Ground

   1. If the power and/or ground value is not as specified, repair defective wiring as required and do close out.
   2. If the power and/or ground value is as specified, continue with next step.

3. For Audio Bus, disconnect VHF COMM units 1 and 2 and VHF NAV units 1 and 2. Perform a continuity check as follows:

   From	To	Result
   A9P1-d	A1P1-56
   A9P1-p	A1P1-70
   A9P1-d	A3BP1-42
   A9P1-p	A3BP1-29
   A9P1-c	A2P1-56
   A9P1-n	A2P1-70
   A9P1-c	A4BP1-42
   A9P1-n	A4BP1-29

   1. If there is no continuity, repair defective wiring as required and do close out.
   2. If there is continuity, continue with next step.

4. For Marker Sensitivity, disconnect Audio Panel 2 connector A9P2. Disconnect RMU 1 connector A25P1 and RMU 2 connector A26P1. Perform a continuity check as follows:

   From	To	Result
   A9P2-L	A25P1-i
   A9P2-L	A26P1-i

   1. If there is no continuity, repair defective wiring as required and do close out.
   2. If there is continuity, continue with next step.

5. For IAC Aural Warnings, remove IAC 1 and IAC 2. Perform a continuity check as follows:

   From	To	Result
   A9P2-B	A11BP1-77
   A9P2-W	A11BP1-76
   A9P2-X	A10CP1-32
   A9P2-G	A10CP1-33

   1. If there is no continuity, repair defective wiring as required and do close out.
   2. If there is continuity, continue with next step.

6. For Emergency Audio, remove VHF COMM unit 2. Perform a continuity check as follows:

   From	To	Result
   A9P1-G	A2P1-31
   A9P1-m	A2P1-29

   1. If there is no continuity, repair defective wiring as required and do close out.
   2. If there is continuity, continue with next step.

7. For TCAS Voice, remove the TCAS unit. Perform a continuity check as follows:

   From	To	Result
   A9P2-t	A7EP1-3F
   A9P2-Z	A7EP1-3G

   1. If there is no continuity, repair defective wiring as required and do close out.
   2. If there is continuity, continue with next step.

8. For GPWS Audio, remove the GPWS unit. Perform a continuity check as follows:

   From	To	Result
   A9P2-m	A64BP1-C13
   A9P2-J	A64BP1-D13

   1. If there is no continuity, repair defective wiring as required and do close out.
   2. If there is continuity, continue with next step.

9. For CVR Interface, remove the CVR unit. Perform a continuity check as follows:

   From	To	Result
   A9P2-V	A51P1-37
   A9P2-r	A51P1-35

   1. If there is no continuity, repair defective wiring as required and do close out.
   2. If there is continuity, continue with next step.

10. For Cockpit Loudspeakers, perform a check for the cockpit loudspeakers. Refer COCKPIT LOUDSPEAKERS INOP.

    1. If system checks are good, do close out.
    2. If fault remains, continue with next step.

11. Remove Audio panels 1, 2 and 3. Perform a resistance check of the Audio Bus Thermistors as follows:

    From	To	Expected result	Result
    A9P1-d	A9P1-p	R20 & R22 = 50 Ohms
    A9P1-c	A9P1-n	R21 & R23 = 50 Ohms

    1. If the resistance values are not as specified, repair defective wiring as required or replace the bus-termination resistors and do close out.
    2. If the resistance values are as specified, continue with next step.

12. Replace Audio Panel 2.
13. Do close out.