Heidelberg SM52 Main Motor Needed (Part# G4.101.2003)

MarkG

New Member
Joined
2023
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Geo
Alsip, IL
Looking for a new or used main motor for our 1999 SM52 Original Part # is G4.101.2003 or help with current replacement. We replaced original motor with a used motor, but it does not rotate smoothly during inching or wash-ups. Motor runs fine during idle and in production.
 
If it doesn't run smoothly during crawl speed and inching, most probably the main motor encoder is faulty. Have you tried to replace that?
 
  • No, not exactly. The original encoder "cap" on the end of the motor was damaged in shipping, so we replaced with cap from old motor. We did not change out the mounting plate or change the position of the plate on the new motor. I was told that the complete encoder should only be changed at the factory. Is that not correct? Can it be done in the field?
     
    No, not exactly. The original encoder "cap" on the end of the motor was damaged in shipping, so we replaced with cap from old motor. We did not change out the mounting plate or change the position of the plate on the new motor. I was told that the complete encoder should only be changed at the factory. Is that not correct? Can it be done in the field?



    That's the issue: the encoder is having some problems. If you look down at the encoder from above, while the connector is positioned at the 6 o'clock mark. There are two opto sensors around the 5 o'clock position, with the other sensors roughly located at 12, 3, and 9 o'clock. The problem seems to stem from the two sensors at the 5 o'clock position. These sensors, along with the plate in front of them, are often covered by brake dust and particles. The plate has a small slot that helps calibrate the light sensors.

    These two sensors work with a flip-flop function, meaning they can't activate or deactivate at the same time. These sensors should be cleaned. Blowing air to clean them won't work. However, there's a method that has worked for me on a few occasions. Place the encoder in a clean container or bowl, and submerge it in fresh, unused isopropyl alcohol. Shake it gently a few times, then remove it and place it upside down on a paper towel. Let the alcohol evaporate completely. For faster results, you can leave it outside in sunlight to help with the evaporation.

    Although the encoder is aligned and mounted on the motor at the factory, it can still be installed afterwards if needed.

    Let’s focus on cleaning the encoder first, and then I can address its positioning.

    Good luck!
     
    MarkG, Follow Mathew's advice. Encoder is your problem not the whole motor.
     
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