Message Name:

NO R-CLOCK BUS OUTPUT

Message Code:

B3-397681

Associated CAS:

None

Remote Data Concentrator (RDC) B CHANNEL is reporting the RIGHT CLOCK BUS input absent.

• Digital Clock (A121)
• Remote Data Concentrator (RDC) (A13)
• Associated Wiring

Advisory Wire/Service Bulletin: None

Forum Articles/Infoservice/Newsletter: None

1. Reset CLOCK PWR (CB3-F9) and CLOCK (CB3-F8) circuit breakers.

   1. If system check passes, do close out.
   2. If fault remains, continue with next step.

2. Confirm presence of the 28 VDC and Grounds at the Clock connector A121P1. Repair/replace as required.

   1. If system check passes, do close out.
   2. If fault remains, continue with next step.

3. Verify the bus speed strapping (pin C & P) at clock connector A121AP1. Repair as required.

   1. If system check passes, do close out.
   2. If fault remains, continue with next step.
      NOTE: Aircraft pre S/B100-34-36 and Aircraft 20407 and below: Pin C & P are connected. Aircraft post S/B 100-34-36 and Aircraft 20408 and up: Pin C & P are NOT connected.

4. Do the wiring check of the ARINC 429 data bus CLK-1 from the Clock connector A121P1 to the RDC connector A130DP1. Repair/replace as required.

   1. If system check passes, do close out.
   2. If fault remains, continue with next step.

5. Replace the Clock.

   1. If system check passes, do close out.
   2. If fault remains, continue with next step.

6. Replace the RDC.
7. Do close out.