How do I check the electrical box to help you choose a used YCM?

Author:J           Date:2025-11-01

Step 1: Safety Preparation and Static Visual Inspection (Power Off Operation)

Complete Power Off: Ensure the main power switch for the used YCM is turned off and a warning sign is displayed. Ideally, completely disconnect the upstream power supply. This is a prerequisite for all operations.

Appearance and Cleaning: Open the electrical box door and first observe the overall cleanliness of the interior. Thick layers of dust and oil indicate that the equipment is operating in a harsh environment or lacks maintenance, which will severely affect heat dissipation and cause premature aging of components. Look for metal shavings, which may indicate insufficient protection during processing.

Structural Integrity: Check the inside of the box for rust, especially near the cooling system. Moisture corrosion is a major enemy of circuit boards. Check the cable trays and harnesses for neatness and for any messy, haphazardly installed or modified wires. Standardized wiring indicates the maintenance level of the original manufacturer or previous owner.

Step 2: Critical Component Status Inspection (Power Off Operation)

Contactors and Relays: Locate the main power contactor, spindle contactor, servo drive contactor, etc. Check their contacts for severe electrical corrosion (burning, unevenness). Minor signs of use are normal, but severe electrolytic corrosion indicates excessive current load or frequent start-stop cycles, posing a potential hazard.

PLC and I/O Modules: Observe the status indicator lights of the programmable logic controller (PLC) unit. Record its model number for future spare parts retrieval. Check the I/O module wiring for secure connections.

Servo Drivers and Spindle Drivers: This is the core of the electrical box. Carefully observe the driver unit for any residual alarm codes (some may retain historical alarms even after power failure). Check its display panel for any abnormalities. Look for signs of capacitor bulging or leakage, which are clear signs of component aging.

Terminals and Cables: Gently wiggle the main power connectors and motor power cable terminals by hand (wearing gloves is acceptable) to check for looseness. Loose terminals can overheat due to excessive contact resistance, posing a significant danger. Check cable connectors for signs of overheating, melting, or deformation.

Step 3: Power-On Dynamic Check (Power on, but do not start the spindle and servo)

Sequential Power-On: Close the main power supply, but do not immediately start the machine tool in the "Ready" state.

Observation and Listening: Listen for any abnormal "buzzing" discharge sounds or "clicking" sounds from relays malfunctioning inside the electrical box. Also, note any sudden burning odor.

Check Power Supply Voltage: Use a multimeter to check if the three-phase input voltage is balanced and stable at the test points or input terminals of the power module. This is fundamental for the normal operation of all electrical components.

Driver Self-Test: Observe the indicator lights of the servo and spindle drives. Under normal circumstances, after power-on, a self-test should be performed, followed by a "ready" indicator or a similar green light, not an alarm red light. If an alarm sounds immediately upon power-on, it indicates a hardware or parameter fault, requiring close monitoring.

Fan and Cooling: Confirm that the cooling fan in the electrical box is operating normally. Poor heat dissipation is one of the main causes of electronic component failure.

Step Four: Machine Tool Function Testing

This is crucial for linking electrical status with mechanical performance.

In manual mode, slowly move each axis, paying attention to any abnormal sounds or alarms from the servo drive.

Start the spindle at low speed and observe the spindle drive's operating status. Run the tool magazine and check whether the related relays and sensors operate accurately and decisively.

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