When a rotary evaporator encounters an issue, it's important to identify the problem and take appropriate corrective actions. Below is a detailed troubleshooting guide that outlines possible issues, their causes, and recommended solutions.
**Problem: Vacuum Cannot Be Drawn**
- **Cause**: The presence of solvent in the container may limit the vacuum due to its saturated vapor pressure.
- **Solution**: Empty the solvent and perform an empty bottle test.
- **Cause**: The vacuum pump’s capacity has decreased over time.
- **Solution**: Replace the vacuum pump oil or water, and perform cleaning and maintenance.
- **Cause**: Leaks in the vacuum tubing, loose joints, or faulty vacuum gauge.
- **Solution**: Inspect the entire vacuum line step by step and eliminate leaks.
- **Test for Airtightness**: Perform a pressure test with no solvent present. Close all external valves and pipelines, then observe the vacuum gauge for one minute. If the pointer remains steady, the system is airtight. Otherwise, there is a leak.
- **Cause**: Poor sealing at glass joints or flanges.
- **Solution**: Reassemble the components, clean the glass ground joints, apply vacuum grease, and tighten the flanges securely.
- **Cause**: Failed or damaged seals.
- **Solution**: Replace the faulty seal.
- **Cause**: Debris in the discharge valve or pressure control valve.
- **Solution**: Clean the affected valves thoroughly.
- **Cause**: Broken glass components.
- **Solution**: Replace or repair the damaged glass parts.
**Problem: Bath Not Heating**
- **Cause**: No display on the bath pot.
- **Solution**: Check the power supply (220V).
- **Cause**: The “OUT†or “ON†green indicator on the temperature controller is not lit.
- **Solution**: Replace the heating coil, solid-state relay, or relay board.
- **Cause**: The bath temperature is below the set point, but the “OUT†or “ON†indicator is not lit.
- **Solution**: Replace the temperature controller.
- **Cause**: The temperature controller displays “OVER†or “000.â€
- **Solution**: Check the probe wiring or replace the probe.
- **Cause**: The bath temperature is higher than the set point, but the “OUT†or “ON†indicator does not turn off (1–2°C is normal).
- **Solution**: Replace the temperature controller.
- **Cause**: The “OUT†or “ON†indicator is off, but the system continues to heat.
- **Solution**: Replace the solid-state relay or relay board.
- **Cause**: The digital bath temperature reading is significantly lower than the actual temperature.
- **Solution**: Replace the probe or temperature controller.
**Problem: Motor Not Turning**
- **Cause**: The electrical control box indicator or digital display is not lit.
- **Solution**: Replace the fuse or check the power supply.
- **Cause**: The control box indicator is on, but the internal connections are loose or disconnected.
- **Solution**: Reconnect the wires or reinsert the plug.
- **Cause**: Abnormality in pins 1 and 2.
- **Solution**: Replace the circuit board or electric control box.
- **Cause**: Inverter interference causing "OU" display.
- **Solution**: Ground the system or move to a different location.
- **Cause**: Inverter protection function activated.
- **Solution**: Follow the inverter manual (Page 33) for troubleshooting.
**Problem: Motor Speed Issues**
- **Cause**: Open circuit in the speed measuring generator coil.
- **Solution**: Use a multimeter to check resistance between pins 1 and 2 of the seven-pin plug. Normal resistance should be approximately 400Ω.
- **Cause**: Generator disconnection or coil failure.
- **Solution**: Replace the coil or reset the trip point.
- **Cause**: Short circuit between generator coil and housing.
- **Solution**: Loosen the motor rear generator cover to fix the short.
- **Cause**: Magnetic ring not rotating.
- **Solution**: Tighten the M5 nut.
- **Cause**: Broken magnetic ring.
- **Solution**: Replace the magnetic ring.
**Problem: Motor Overheating**
- **Normal Condition**: Motor temperature rise (case temp - room temp) ΔT ≤ 40°C is acceptable.
- **Solution**: Continue use without intervention.
- **Abnormal Condition**: ΔT > 40°C.
- **Solution**:
1. Reduce the agitator paddle size to lower the load.
2. Adjust speed to a moderate level.
3. Avoid rotational resonance points.
4. Check and remove mechanical resistance.
5. Maintain sealed and lubricated parts.
**Note**: Always refer to the manufacturer’s manual for specific details and safety precautions when performing repairs or adjustments.
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