The radar scanner transmits a (often called a heading mark or sync pulse) once per revolution. The display processor needs this pulse to:
Safety note
A indicates a critical communication failure between the display processor and the scanner unit (transceiver). When this error triggers, the system loses the timing reference required to map echoes, causing the radar sweep to freeze or fail entirely. This guide provides an actionable troubleshooting workflow to diagnose and resolve this system fault. Understanding the Sync Signal
Resolving a "No Sync Signal" requires a methodical approach to avoid unnecessary parts replacement. The first step is a "heartbeat check": verifying if the antenna is rotating. If the antenna is stationary, the issue is likely a power failure or motor fault, not the sync circuit itself. Assuming the antenna rotates, the next step is utilizing built-in test equipment (BITE) or diagnostic software available on JRC units. However, the most definitive test is often a continuity check or voltage measurement. A marine electronics officer or technician will measure the voltage at the scanner unit output and compare it to the input at the display unit. If the signal exists at the source but not at the display, the cable is the fault. If the signal exists at the display input but the alarm persists, the display board is likely defective. no sync signal jrc radar
: A failure in the radar interface circuit or the signal processing board (often the "TRX" or "Control" board). Troubleshooting Steps
The multi-core data cable running up the mast or radar arch flexes under heavy seas, breaking internal copper conductors.
If you have an all-JRC installation, contact a specialized marine electronics technician to run a signal analysis. The radar scanner transmits a (often called a
In JRC architecture, the sync signal is conditioned on specific boards:
Common causes (ordered by frequency / ease of verification)
Interrupts the transmission of the synchronization data stream. If the antenna is stationary, the issue is
The inter-switching cable can break or suffer from saltwater corrosion inside the outer insulation. Inspect the cable for physical damage, particularly near the scanner entry.
Marine radar systems rely on microsecond-level timing accuracy to accurately calculate target distances.