Possible Causes Of Trouble - Mitsubishi Electric M80 Series Maintenance Manual

M800/M80/E80 Series Maintenance Manual
5 Troubleshooting

5.1.1 Possible Causes of Trouble

The most common cause is a cable contact defect and wire breakage defect.
Is the connection correct?
Are the cables bent or stepped on?
Are the joints of the cables and connectors deteriorated?
Was a continuity test done on the cables?
Is any of the terminal block or connector screws loosen?
Is there any oil or cutting oil splattered onto the cables?
Was a cable disconnected while the power was ON?
Is any cable overheated?
Often trouble occurs due to fluctuation in the power voltage or noise from the communication cable.
Is the power voltage always correct?
Is the power frequency always correct?
Does the voltage fluctuate depending on the time?
Does the voltage drop momentarily when a peripheral device starts operation?
Was there an instantaneous power failure before the trouble?
Have measures against noise been taken for each unit?
Are the communication and power system cables separated and laid?
Is the communication cable shield sufficient?
The trouble may also occur due to sudden temperature changes or vibration and impact, although this is rare.
Are the ambient temperature and humidity adequate?
Is the fan in the panel where the unit is stored rotating?
Is the panel fixed on a flat and stable floor with little vibration?
141 IB-1501273-F