Service manual
FIXING UNIT
2-O-6
2 UNIT EXPLANATION
[4] Fixing Temperature Control
The fixing upper roller is heated by L2 (fixing upper
roller heater lamp 1) and L3 (fixing upper roller heater
lamp 2) and the fixing lower roller is heated by L4 (fixing
heat roller heater lamp 3) via the fixing heat roller. The
PRCB (printer control board) detects the temperature
of the fixing rollers using TH1 (fixing unit temperature
sensor 1) and controls L2, L3, L4 via the ACDB (AC
drive board).
1. Operation
a. Temperature control
The PRCB turns ON the fixing heater lamp circuit
in ACDB as soon as the main switch is turned
ON, causing L2, L3, and L4 to go ON until the fix-
ing upper roller reaches the specified tempera-
ture. Series/parallel switching control is
performed over L2 and L3 to prevent flicker (flu-
orescent lamp etc.). Immediately after L2 and L3
are turned ON, they are connected in series to
suppress rush current. Then they are connected
in parallel. TRC1 (triac 1), TRC2 (triac 2) and
TRC3 (triac 3) are used for this series/parallel
switching control.
Set temperature: 200°C
Warm-up time: 6 minutes or less (at room tem-
perature 20°C)
PRCB
DCPS2
DCPS1
ACDB
L4TS2
TH1
TH2
TH3
TH4
RL1
TRC1
TRC2
TS1
L2
TH1 ANG 1
TH1 ANG 2
TH2 ANG 1
TH2 ANG 2
TH3 ANG 1
TH3 ANG 2
TH4 ANG 1
TH4 ANG 2
L2 CONT
L3 CONT
L2&L3 CONT
L4 CONT
5VDC
SGND
24VDC
PGND
24VDC
RL1 CONT
AC(H)
AC(C)
L4 DRIVE
L2 DRIVE
L2 TRIG
L3 DRIVE
L3 TRIG
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