6.Troubleshooting 
173 
 
Error Name/Error Condition/Major Cause/Solution 
Laser unit thermistor error 
  The laser unit thermistor detected a temperature lower than -30°C for more than 
4 sec. 
  The laser unit thermistor detected a temperature higher than 105°C for more 
than 1 sec. 
  Thermistor disconnected (causes an extremely low temperature reading) 
  Defective harness 
  Defective main board 
1.  Turn the power OFF and ON. 
2.  Replace the laser unit thermistor. 
 
 
SC 4xx (Image Transfer and Transfer Errors) 
Error Name/Error Condition/Major Cause/Solution 
An error signal is detected for 0.2 seconds when changing the development unit. 
  HVP harness damaged and short circuited 
  Defective the HVP 
  AIO terminal damaged and short circuited 
1.  Turn the power OFF and ON. 
2.  Replace the main board. 
3.  Replace the transfer roller. 
4.  Replace the interface harness of the HVP. 
5.  Replace the HVP. 
SC 5xx (Motor and Fusing Errors) 
Error Name/Error Condition/Major Cause/Solution 
  The machine does not detect a main motor lock signal within 2 seconds after 
the main motor started to rotate. 
  The machine does not release a main motor lock signal within 2 seconds after 
the main motor switched off. 
  The machine detects a main motor lock signal every 100 msec. for seven times 
consecutively, after the main motor started to rotate stably.