The core maintenance points of Mitutoyo roughness tester are as follows: diagnose first, then repair; First external, then internal; Software first, hardware later. 1、 Common fault classification and preliminary diagnosis: Unable to turn on/no display. Key point 1: Check the power system battery: Confirm whether the battery is dead or aging (you can try using an adapter for power supply). Adapter: Check if the output voltage and current meet the requirements (usually 5V or 9V DC). Power switch/board: Check if the switch is damaged, and if there is corrosion or desoldering in the internal power circuit. Key point 2: Motherboard malfunction This is the most serious situation, and it is necessary to check whether the motherboard has water ingress, burn marks, and whether the crystal oscillator is vibrating. Key point 1 for abnormal, inaccurate or unstable measurement values: Driver and probe assembly (core components) guide rail and slider: This is a high-risk area for faults. Check the guide rail for scratches, dirt, and wear. Clean and lubricate (special lightweight clock oil or instrument rail oil must be used, avoid using ordinary engine oil). Drive motor/belt: Check if the motor runs smoothly and if the drive belt is aged, slipping, or broken (SJ-210 is a belt drive, common faults). Probe return (zero point): Can the probe automatically return to mechanical zero point when turned on. Is the position sensor (photoelectric sensor) obstructed by dust. Key point 2: Measuring needle and probe. Measuring needle: whether it is severely worn or broken. This is the most vulnerable consumable and should be inspected or replaced for testing first. Measuring rod/hinge: Check whether the measuring rod moves flexibly and whether the hinge part is loose. Is the gemstone bearing damaged. Sensor: Check if the differential transformer type sensor coil inside the probe is damaged (requires professional inspection). Please refer to the appendix of the user manual for the corresponding model to display the error code. The error code is the most direct diagnostic clue. Common code: "E09" and other driver errors: driver stuck, belt broken, motor failure. Measurement range error: The probe sensor signal exceeds the limit, which may cause the measuring needle to get stuck or the sensor to malfunction. Battery related error: Power management circuit or battery issue. Check if the button board wiring is loose or oxidized due to button failure or screen issues. If the screen displays but is partially missing, it may be due to damage to the wiring or the LCD screen itself. 2、 Key points for maintenance and calibration of key components: Disassembly and cleaning of the drive assembly (high-risk operation): It is necessary to carry out it in a clean and dust-free environment. Mark the positions of all parts before disassembly. Disassemble the casing and circuit board in sequence, and finally expose the guide rail. Cleaning: Clean the guide rail and slider with anhydrous ethanol and dust-free cloth. It is strictly prohibited to touch the working surface of the guide rail directly with hands. Lubrication: Apply a very small amount of specialized lubricating oil on the guide rail and repeatedly run the driver to evenly distribute it. Key points for checking probe sensors: The probe is extremely precise and fragile, and it is not recommended for non professionals to disassemble the sensor body. Preliminary judgment can be made by measuring the resistance of the sensor coil (compared with the normal value). Typically, the coil resistance ranges from tens to hundreds of ohms. Check if the sensor core (connected to the measuring rod) moves smoothly and if there is friction. Calibration (must be performed after repair) Key point 1: After replacing key components (especially measuring needles and probes) with standard calibration templates, Mitutoyo original or certified roughness standard templates must be used for calibration. Calibration includes vertical (magnification) and horizontal (stroke) calibration. Key point 2: Entering calibration mode is usually done by long pressing a specific combination of keys (such as "ENTER" and "▲") to enter the service menu and select "Calibration". According to the on-screen prompts, perform multiple measurements on the template, and the instrument will automatically calculate and store the calibration coefficient. Key point 3: Verify using templates with different Ra values to ensure that the error is within the nominal accuracy range of the instrument. 3、 Summary of maintenance process information collection: Record the model, serial number, error code, and fault phenomenon (when and under what conditions it occurred). Preliminary investigation: Check for physical damage to the battery/power supply, probe, and appearance. Attempt to restore factory settings (note backup data). Functional diagnosis: Attempt to power on, enter diagnostic mode (if available), manually run the drive to listen for sound and observe actions. Step by step disassembly: Take photos and record each step from the outside to the inside, and properly place screws and small parts. Fault repair: Targeted cleaning, lubrication, and replacement of damaged parts (commonly used spare parts: belts, measuring needles, batteries). Assembly and Calibration: Carefully assemble and perform comprehensive electrical and mechanical calibration. Final testing: Use multiple templates to test under different parameters to ensure functional recovery. 4、 Special precautions and suggestions for anti-static: Before operating the circuit, wear an anti-static wristband. Special tool: Use a suitable precision screwdriver to avoid scratching the screws. Source of spare parts: Try to use original or high-quality compatible spare parts, especially measuring needles and belts. Technical information: Find the corresponding model's Service Manual instead of just the User Manual. Act within your means: If it involves motherboard chip level maintenance or sensor replacement, and if you do not have professional equipment and experience, it is recommended to send it for repair to Sanfeng Maintenance Center or a professional metrology instrument repair institution. Self repair may result in secondary damage and cause the instrument to lose calibration traceability. If your "karyotype" specifically refers to a particular model or malfunction, please provide more detailed information for a more accurate answer. I hope this key point can be helpful to you!