No Sync Signal Jrc Radar May 2026

Title: Troubleshooting "No Sync Signal" on JRC Radars: Causes and Solutions

: Check the multicore cable connecting the display unit to the scanner. Pay close attention to the screening and ensure every wire is firmly seated in its terminal. Run the Self-Test : Most JRC models, like the JMA-9100 series no sync signal jrc radar

Cause A: Intermittent or Damaged Scanner Cable

• Symptoms: Sync fails only when the radar warms up or when the vessel vibrates.
• Fix:
  1. Torque Check: Ensure all coaxial connectors are tight (hand-tight plus 1/8 turn). Loose connectors allow micro-vibrations that fracture sync wires.
  2. Desiccant Replacement: JRC scanner housings have a desiccant bag. Replace it every 6 months. Humidity is the #1 killer of sync encoders.
  3. Slip Ring Rotation: If the vessel is alongside for weeks, manually rotate the scanner by hand (power off) 10 full turns. This wipes slip ring contacts clean.
  4. Ground Integrity: Measure resistance between scanner chassis and display ground. It must be <1 Ohm. Floating grounds induce common-mode noise that drowns the low-voltage sync pulse.
  • Open scanner pedestal. Inspect for mouse nests, corrosion, loose terminations.
  • Measure sync signal voltage with a multimeter at the display’s rear terminal (look for 2.5–5V AC or DC depending on model).
  • Perform a "Heading Alignment" – if the heading marker drifts, the sync processing chip may be failing.
  1. Locate the Sync output pins on the JRC terminal block (Refer to JRC maintenance manual—typically pins 3 & 4 on CN-1).
  2. Probe between Sync+ and Sync-.

     : Even a momentary drop in ship power can trigger communication errors between the processor and the scanner. Step-by-Step Troubleshooting Perform a Hard Reset Title: Troubleshooting "No Sync Signal" on JRC Radars: