7. Maintenance 
 
 
 
7 - 2 
 
 
WARNING
1.  Before starting maintenance or inspections, turn the main circuit power and 
control power both OFF. Wait at least ten minutes for the CHARGE lamp to 
turn OFF, and then using a tester, confirm that the input and output voltage 
are zero. Failure to observe this could lead to electric shocks. 
2.  Inspections must be carried out by a qualified technician. Failure to observe 
this could lead to electric shocks. Contact your nearest Mitsubishi branch or 
dealer for repairs and part replacement. 
 
 
CAUTION
 
1.  Never perform a megger test (measure the insulation resistance) of the 
servo drive unit. Failure to observe this could lead to faults. 
2.  The user must never disassemble or modify this product. 
 
 
7-1 Inspections 
Periodic inspection of the following items is recommended. 
(1)  Are any of the screws on the terminal block loose? If loose, tighten them. 
(2)  Is any abnormal noise heard from the servomotor bearings or brake section? 
(3)  Are any of the cables damaged or cracked? If the cables move with the machine, periodically 
inspect the cables according to the working conditions. 
(4)  Is the core of the load coupling shaft deviated? 
 
 
7-2 Service parts 
A guide to the part replacement cycle is shown below. Note that these will differ according to the 
working conditions or environmental conditions, so replace the parts if any abnormality is found. 
Contact Mitsubishi branch or your dealer for repairs or part replacements. 
 
Part name  Standard replacement time Remarks 
Smoothing capacitor 10 years 
Cooling fan 
10,000 to 30,000 hours 
(2 to 3 years) 
Servo drive unit 
Battery 10,000 hours 
Bearings  20,000 to 30,000 hours 
Detector  20,000 to 30,000 hours 
Servomotor 
Oil seal, V-ring  5,000 hours 
The standard replacement time is 
a reference. Even if the standard 
replacement time is not reached, 
the part must be replaced if any 
abnormality is found. 
 
(1)  Power smoothing capacitor  : The characteristics of the power smoothing capacitor will deteriorate 
due to the effect of ripple currents, etc. The capacitor life is greatly 
affected by the ambient temperature and working conditions. 
However, when used continuously in a normal air-conditioned 
environment, the service life will be ten years. 
(2) Relays  : Contact faults will occur due to contact wear caused by the 
switching current. The service life will be reached after 100,000 
cumulative switches (switching life) although this will differ according 
to the power capacity. 
(3)  Servomotor bearings  :  The motor bearings should be replaced after 20,000 to 30,000 hours 
of rated load operation at the rated speed. This will be affected by 
the operation state, but the bearings must be replaced when any 
abnormal noise or vibration is found in the inspections. 
(4)  Servomotor oil seal, V-ring  :  These parts should be replaced after 5,000 hours of operation at the 
rated speed. This will be affected by the operation state, but these 
parts must be replaced if oil leaks, etc., are found in the inspections.