Rev. A Product Overview Appendix D-67
TM-H6000/H6000P Service Manual
Confidential
Rush Current Control Circuit
The rush current control circuit controls rush current when the power source is turned on. This
printer has large-capacity condensers to facilitate stable operation of mechanism drivers and
circuits. Therefore, an excess of rush current is generated when the power is turned on. This
circuit controls the rush current.
The CN18 external power source is connected to the CN19 switch. Q61 is Off when the switch is
turned On. Accordingly, the current that flows when the switch is turned on is supplied to the
respective parts via the power thermistor (TH1). The power thermistor controls the input
current with an in-line resistor (room temperature: 2.2 Ω). When the printer circuit begins to
operate, GA (U30) output OUTH is HIGH, and Q61 goes On. This bypasses TH1.
The OUTH signal is connected to the RESET signal internally by the GA, causing TH1 to be
bypassed when RESET is HIGH.
The power thermistor (TH1) has high resistance at room temperature, but the resistance value
decreases with heat generated by current flow. The power thermistor immediately begins to
heat up when 24V is turned on, but cools down when it is bypassed at the time the circuit begins
to operate, regaining its high resistance. Accordingly, it controls the rush current when the
power source is turned on again.
Figure D-66
24VB
OUTH
SIN2-1
PIN1
MIN1
CN18
1
2
3
SH
F1
C41
CN29
1
2
Q62
Q61
TH1
D70
R244
R245
C44C43C42
D16
C40
L3
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