MX-6240N, MX-7040N (serv.man26). Section 7 Troubleshooting - Updated November 2012 - Sharp Copying Equipment Service Manual (repair manual). Page 56

MX-7040N  TROUBLESHOOTING  7 – 56

 

 

Trouble content

The temperature does not reach the specified level 
within the specified time after turning ON the power 
relay.

Detail

PCU

Cause

Thermistor trouble.
Warm air heater trouble
Warm air heater harness and connector connection 
trouble
A3 2-stage LCT control PWB trouble
Thermostat trouble.
AC power trouble
Insertion detection switch 2 trouble
Heater relay PWB trouble

Check & Remedy

Check the thermistor and its harness.
Check the thermistor input circuit section of the A3 2-
stage LCT control PWB.
Check for disconnection of the warm air heater and 
the thermostat.
Check the insertion detection switch 2.
Check the heater relay PWB.
Check the heater control circuit of the AC PWB and 
that of the A3 2-stage LCT control PWB.

Trouble content

The temperature at the warm air outlet port exceeds 
the specified level.

Detail

PCU

Cause

Thermistor trouble.
Warm air heater harness and connector connection 
trouble
Heater relay PWB trouble
A3 2-stage LCT control PWB trouble

Check & Remedy

Check the thermistor and its harness.
Check the thermistor input circuit section of the A3 2-
stage LCT control PWB.
Check the heater relay PWB.
Check the heater control circuit of the A3 2-stage LCT 
control PWB.