Encoder maintenance！

In numerical control machine, photoelectric pulse encoders are used as components for speed and position detection. The failure rate is high and the external performance is various.  in the maintenance practice, we will generalize and classify the faults of the photoelectric pulse encoders to make fault more clear.
Fault classification is as follows:

• The encoder itself is faulty: it means that the components of the encoder itself are faulty, so that they cannot generate and output the correct waveform. In this case, the encoder needs to be replaced or its internal components must be repaired.
  
• Encoder connection cable failure: This type of failure has the highest probability of occurrence and is often encountered in maintenance and should be a priority. Usually the encoder cable is open, shorted or poorly connected, in which case the cable or connector needs to be replaced. Special attention should also be paid to whether the cable is not tightly fastened, causing loosening to cause open welding or breaking, and the cable needs to be clamped.
     
• Encoder +5V power supply drop: It means that the +5V power supply is too low, usually cannot be lower than 4.75 V. The result is the power supply failure or the power transmission cable resistance is too large to causes loss. Then need to repair the power supply or replace the cable.
        
• Absolute encoder battery voltage drop: This type of fault usually has a clear alarm and then need to replace the battery, if the reference point position memory loss, the reference point return operation must be performed.
       
• The shield cable of the encoder cable is not connected or disconnected: this will introduce interference signals, make the waveform unstable, affect the accuracy of communication, and must ensure reliable welding and grounding of the shielded wire.  
  
• Encoder installation loose: This kind of failure will affect the position control, accuracy, resulting in the position deviation of the stop and the movement is out of tolerance , please pay special attention when the servo system overload alarm is generated just after the start,.    
  
• Grating pollution: This will cause the signal output amplitude to drop. You must use a cotton wool with absolute alcohol to gently wipe off the oil. 
        
  

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