Error code
Item
Description
Ref. page
Main
Sub
L8
3
Remedy
Check the following items:
1) AE sensor or its input circuit
2) Copy lamp control circuit (copy lamp control signal)
After repair, turn off/on the power switch.
H2
0
Content
Fuser section thermistor trouble
Detail
The voltage across the thermistor input circuit remains 4.6V or more for 1500 ms or more.
Cause
1) Thermistor and its input circuit (main control PWB) trouble (disconnection)
Remedy
Check the thermistor and its input circuit (main control circuit) for disconnection.
AFter repair, used simulations 14 to cancel the self diag.
H3
0
Content
Abnormally high temperature in the fuse section
8-11
Detail
The voltage across the thermistor input circuit remains 1.39V or less for 1500 ms or more.
(A high temperature above 241 C is detected.)
CAuse
1) Thermistor and its input circuit (main control PWB) trouble (disconnection)
2) Heater lamp control signal and its control circuit trouble
(The heater lamp remains ON.)
Remedy
Check the following items:
1) Thermistor and its input circuit (main control PWB) disconnection
2) Heater lamp control signal and its control circuit
After repair, use simulations 14 to cancel the self diag.
H4
0
Content
An abnormally high temperature in the fuse section
8-11
Detail
1) The voltage across the thermistor input circuit remain 3.39V or more for 1500ms. (A
temperature below 148°C is detected.)
2) The temperature does not reach the specified temperature within 60 sec after starting
warming up.
Cause
1) Thermistor and its input circuit (main control circuit) trouble (disconnection)
2) Heater lamp trouble
3) Heater lamp control signal and its control circuit trouble (The heater lamp remains ON.)
Remedy
Check the following items:
1) Check the thermistor and its input circuit (main control PWB) for disconnection or shot.
2) Heater lamp control signal and its control circuit
3) Heater lamp
After repair, use simulations 14 to cancel the self diag.
U2
1
Content
In the main PWB EEPROM data sum check, the data do not correspond to the CPU data.
8-12
Cause
1) Main PWB EEPROM trouble
2) Main control circuit trouble
3) Communication line trouble between the main PWB EEPROM and the CPU
4) CPU trouble
5) Data bus line trouble
Remedy
Check the following items:
1) main PWB EEPROM
2) Memory control circuit
3) Communication line between main PWB EEPROM and CPU
4) CPU
5) Data bus line
After repair, use simulations 16 to cancel the self diag.
When the power is turned on, data in the main PWB EEPROM are transferred to the CPU
to perform sum check. The operation can be checked at that time.
4
Content
memory line communication trouble
8-12
Detail
1) In access to the main PWB EEPROM, the respond command ACK is not inputted to
the CPU.
2) When writing data into the main PWB EEPROM, the write enable signal is not inputted
to the CPU for 11ms or more.
Cause
1) Main EEPROM RAM trouble
2) Memory control circuit trouble
3) Communication line trouble between main PWB and CPU
4) CPU trouble
5) Data bus line trouble
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