User manual

95.08.23.11.30
Color LaserWriter 12/600 PS Basics & Theory 1–120
Fuser Error C:
Abnormality
Detection
Circuit Error
Located in the power supply unit, the fuser abnormality detection
circuit monitors the fuser assembly for voltage compatibility and fuser
heater continuity:
• Voltage compatibility. The fuser assembly abnormality detection
circuit checks that the rated voltage of the power supply unit
matches that of the fuser assembly. For example, if the fuser
assembly for 220 V is connected to the power supply for the 10 V
version, the circuit will recognize it as a mismatch in rated voltage
due to incorrect installation of the fuser assembly. In this case, the
CPU on the DC controller notifies the I/O controller of a power
supply failure and stops the printer.
The rated voltage of the power supply unit is set with the jumper
(JP1) and monitored at pin 4 on Z5. The specified voltage of the
fuser assembly is set with the jumper (JP2) within the fuser
assembly and monitored at pin 7 on Z5. Pin 2 on Z5 goes “L” when
the rated voltage of the power supply unit matches that of the fuser
assembly; it goes “H” when it does not. If there is a mismatch, the
fuser assembly abnormality detect signal (
FXSTS) output from pin
14 on Z5 goes “H,” and the CPU detects the incorrect installation of
the fuser assembly as a result.
• Fuser heater continuity: The fuser assembly abnormality detection
circuit detects the AC current flowing in the fuser heater. If no AC
current flows, the CPU on the DC controller will determine that the
fuser heater wires are broken, notify the I/O controller of a fuser
assembly failure, and then shut off the power.
An abnormality in the AC current sent to the fuser heater is detected
by the voltage generated by T2. The voltage value generated by T2
is monitored at pin 10 on Z5. If the fuser heater is broken and no
AC current flows, Z5-13 will become “H” and the fuser assembly
abnormality detect signal (
FXSTS) output at pin 14 on Z5 goes “L.”
When the AC current flows normally, the
FXSTS signal alternates
between “H” and “L” at a certain frequency. Thus, the CPU can
detect that the fuser heater is broken by the
FXSTS signal.