EPSON Stylus Color 900 Revision C
Operating Principles Electrical Circuit Operation Principles 74
2.3.7 Cooling Fan Driver Circuit
Since this printer drives a large number of PZT elements (total of 480
nozzles) with a high drive frequency (maximum 32.4 K Hz), heat
radiated around the printheads and the trapezoid waveform production
circuit on the C265 main board is considerably large compared to other
printers. Therefore a thernmistor is attached to the heat sink fixed to
thetrapezoid waveform production transistors to prevent the trapezoid
waveform production transistors (Q3 - Q6) and adjacent HIC from
operating abnormally due to high temperature. When the thermistor
detects abnormally high temperature, the printer turns the cooling fan
on to forcibly blow out heat from the lower case. Figure 2-19 shows the
cooling fan driver circuit block diagram. Table 2-19 shows how the
signals output from the ASIC and corresponding fan conditions.
Figure 2-19. Cooling Fan Driver Circuit Block Diagram
Table 2-19. Cooling Fan Control by the ASIC (IC2)
Figure 2-20 shows the main routine of the cooling fan drive.
Figure 2-20. Main Routine of the Cooling Fan Drive
ASIC (IC2, 176- pin) condition Cooling fan condition
High (5 VDC)
On
Low (0 VDC) Off
+42
6.8
CN13
GND
2
1
+35
39 K
E05B59(IC2)
176
FAN
FAN
F6
Drops to 35 V.
Start
YES
YES
E rro r 1
NO
YES
Fan On
YES
Fan Off
NO
NO
YES
NO
E rro r 1
R e tu rn to th e S ta rt.
t1 = Heat sink tem perature on the C 265 m ain board
t2 = TH1 tem perature on the C265 m ain borad.
Is
th e fa n
ro ta tin g ?
t1 >/= 50
°
C
or
t2 >/= 55
°
C
t1 >/= 60
°
C
or
t2 >/= 60
°
C
t1 >/= 40
°
C
or
t2 >/= 50
°
C
t1 >/= 36
°
C
or
t2 >/= 42
°
C
NO
