Minolta Di551 Service Manual page 15

SAFETY INFORMATION
SAFETY CIRCUITS
This machine is provided with the following safety cir-
cuits to prevent machine faults from resulting in seri-
ous accidents.
[1] Overall protection 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 Protection Circuit
CBR1
CBR2
1. Protection by CBR1 and CBR2 (circuit
breakers)
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.
[2]
1.
NF
S-10
Protection by L2, L3 and L4 (fixing
heater lamps) overheating prevention
circuit
PRCB
Control
section
Protection by software
The output voltage from TH1 (fixing tempera-
ture sensor 1) is read by the CPU. If this volt-
age is abnormal, L2 (fixing heater lamp 1), L3
(fixing heater lamp 2), L4 (fixing heater lamp 3)
and RL1 (main relay) are turned OFF.
CAUTION:
Do not change the gap between the roller
and TH1. When replacing TH1, check the
specified mounting dimensions. The RL1
function must not be deactivated under
any circumstances.
TS2
DCPS
TS1
RL1
RL1
L2
AC driver
L3
section
L4