Safety Circuits - Konica Minolta 7020 Service Manual

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SAFETY CIRCUITS

This machine is provided with the following safety
circuits to prevent machine faults from resulting in
serious accidents.
[1] Overall safety circuit
[2] L2 and L3 (fixing heater lamps) overheating
prevention circuit
These safety circuits are described below to provide the
service engineer with a renewed awareness of them in
order to prevent servicing errors that may impair their
functions.
[1] Overall safety circuit protector
1. Protection by CBR1 and CBR2 (circuit
breakers)
CBR1 and CBR2 interrupt the AC line instantaneously
when an excessive current flows due to a short in the
AC line.
CAUTION:
The CBR1 and CBR2 functions must not be
deactivated under any circumstances.
CBR1
NF
CBR2
SAFETY AND IMPORTANT WARNING ITEMS
[2] Protection by L2 and L3 (fixing heater
lamps) overheating prevention circuit
PRDB
Control
section
1. Protection by software
The output voltage from TH1 and TH2 (fixing
temperature sensors 1 and 2) is read by the CPU. If
this voltage is abnormal, L2 (fixing heater lamp 1), L3
(fixing heater lamp 2) and RL1 (main relay) are
turned OFF.
CAUTION:
Do not change the gap between the roller
and TH1, between the roller and TH2. When
replacing TH1, check the specified mounting
dimensions. The RL1 function must not be
deactivated under any circumstances.
xvii
DCPS
TS
RL1
RL1
L2
AC driver
section
L3