Xerox WorkCentre XK50cx, Service Manual

Page: 44 / 109

4-17
Circuit
• +22V Power Controller
Insert the power cord, then power is supplied to
MAIN BOARD through DRIVER PBA CN15.
/POR signal which is output through Reset Circut
activate the MAIN CONTROLLER and approve
/F_POP signal which is output through MAIN
PBA(U9-1) and VREFX(+2.5V) to input terminal
(U30-4,11)of comparison instrument.
When the comparison output(U30:1) is " HIGH",
the output is +22V, when the comparison output is
"LOW", it will be "OFF".(/FAULT_TEST SIGN :
HIGH) Also, after /F_POR is finished, during the
+22V is permitting, when you input(U30-9)
/FAULT_TEST sign as "LOW", the output(U30-1) of
comparison instrument become "LOW" and make
the +22V TR(Q14,TIP112) OFF.
• FAULT TEST CIRCUIT
This is a signal to detect whether the head
receiving the output of head column driver is in a
short. After /FAULT-TEST signal is put out at “low”
and +22V is turned “off”, “OK2PRINT” signal is
entered. The port of KS32C6400 MAIN PBA(U15)
shows normal condition if “H” and a short if “L”. If
you make FAULT-TEST output “L” to detect fault of
the head, +22V gets off. If the head is in a short
(LOW), when the level of “/FAULT-TEST” signal
goes “L” and final “OK2PRINT” output goes “L”.
KS32C6400 MAIN PBA (U15) reads this signal and
checks whether the head input receiving the
driver output is in a short. Diode cathode is
attached to each output transistor collector in the
column driver. 8 anode terminals of diode become
common as one and put out /FAULT signal, which
is pulled up by bias circuit controlled by /FAULT-
TEST and shows the condition by OK2PRINT
through the comparator.
• SUBSTRATE HEAT CIRCUIT
Mono ink cartridge of Babbage head is 600dpi
head that uses pigment ink. It is very sensitive to
the temperature in and around the cartridge. In
particular, the viscosity of ink affects print quality as
it is inversely proportional to temperature by an
exponential function. This signal used to
compensate it helps you get equal inking quality by
warming the ink chamber in the cartridge with
aluminum pattern heater before starting to print if
the surrounding temperature is lower than
standard (below 35°…).(Refer to Timing Chart.) It
sends PRE-HEAT signal through I/O port of
DUOIP2(Color Image Main PBA:U16) and supplies
+12V.
Mono Head
Fig.4-2-2 Temperature around Mono Head
70°C
35°C
Pre-Heat if below 35°c