Brother FAX-2820 Service Manual page 188

Error Code
Symptom
(Hex)
6F
Hardware on the main PCB
turns off the heater forcibly
since the thermistor detects
that the fixing unit
temperature exceeds the
setting one.
70
Not used.
Polygon motor of laser
71
scanner unit ASSY does not
synchronize with the
reference clock.
Beam detect signal of laser
72
scanner unit ASSY cannot
be detected.
73
Toner cartridge or drum unit
not installed.
74
Toner sensor detects no
toner in the toner cartridge.
Develop roller counter
reaches the upper limit.
75
In casing temperature sensor
detects definite temperature
or higher.
76
Fixing unit temperature goes
up too high.
77
Fixing unit temperature goes
up too high. (The machine is
turned off when the error 75,
76 or 78 occurs.)
78
Fixing unit temperature does
not go up. Or heater
thermistor harness is
disconnected or broken.
79
Temperature sensor harness
disconnected or broken.
Probable Cause
Thermistor defective
PS PCB unit defective
Main PCB defective
Laser scanner unit ASSY
harness not connected properly.
Laser scanner unit ASSY
defective
Main PCB defective
Laser scanner unit ASSY
harness not connected properly.
Laser scanner unit ASSY
defective
Main PCB defective
The toner sensor is always ON.
Main PCB defective
Toner empty
Toner sensor PCB defective
Main PCB defective
Fan broken
In casing temperature sensor
defective
Main PCB defective
Fixing unit thermistor defective
(Short-circuited)
PS PCB unit defective
Main PCB defective
The error history disappears.
Fixing unit thermistor harness
not connected properly.
Fixing unit thermistor defective
Halogen heater failure
PS PCB unit defective
Main PCB defective
In casing temperature sensor not
connected properly.
In casing temperature sensor
defective
9 - 7
Solution
Replace the fixing unit.
Replace the PS PCB unit.
Replace the main PCB.
Reconnect the laser scanner
unit ASSY harness.
Replace the laser scanner unit
ASSY.
Replace the main PCB.
Reconnect the laser scanner
unit ASSY harness.
Replace the laser scanner unit
ASSY.
Replace the main PCB.
Install the drum unit.
Replace the toner sensor PCB
ASSY.
Replace the main PCB.
Replace the toner cartridge.
Replace the toner sensor PCB
ASSY.
Replace the main PCB.
Replace the fan.
Replace the in casing
temperature sensor.
Replace the main PCB.
Replace the fixing unit.
Replace the PS PCB unit.
Replace the main PCB.
Leave the machine for 10
minutes while keeping the
power on.
Reconnect the fixing unit
thermistor harness.
Replace the fixing unit.
Replace the PS PCB unit.
Replace the main PCB.
Reconnect the in casing
temperature sensor.
Replace the in casing
temperature sensor.
Confidential