Safety Circuits - Konica Minolta 7145 Service Manual

SAFETY CIRCUITS

This machine is provided with the following safety circuits
to prevent machine faults from resulting in serious acci-
dents.
[1] Overall protection circuit
[2] L2 and L3 (fixing heater lamp/1, /2) overheat-
ing 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 protection circuit
1. Protection by CBR1 and CBR2 (circuit
breaker/1, /2)
CBR1 and CBR2 interrupt the AC line instanta-
neously 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
DCPS
CBR2
SAFETY AND IMPORTANT WARNING ITEMS
[2] L2 and L3 (fixing heater lamp/1, /2)
overheating prevention circuit
1. Protection by software
The output voltage from TH1, TH2 (fixing temper-
ature sensor/1, /2) is read by the CPU. If this volt-
age is abnormal, L2 (fixing heater lamp/1), L3
(fixing heater lamp/2) and RL1 (main relay) are
turned OFF.
CAUTION:
The RL1 function must not be deactivated
under any circumstances.
S-11
DCPS
RL1
CB
RL1
Control
AC driver
section
section
TS
FCB