Nokia 447ZiPlus Service Manual page 15

17” colour monitor
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To manually degauss, it can be operated by selecting "
" from the OSD
Menu and pressing MENU select key , it is similar to auto-degaussing.
MCU will be signaling a "high" level to Q801 , hence the manual degaussing is activated.
OSD lock / unlock function
When the degauss icon "
" is pressing more then 10 seconds, the OSD menu will be forced to enter
OSD lock mode and will not allow function setting.
When OSD is at lock mode, selecting "
"icon from OSD and then press it more than 10 seconds
again, the lock mode will be forced to release and back to the normal.
6-4. Micro-Control Circuit
The monitor uses an advanced CPU (I501) to control the H. center; V. center V. height , pincushion,
2
trapezoid and so on by I
C BUS.
The horizontal sync and vertical sync are buffered by Q550, Q556 and fed to pin39, pin40 of I501, the
output sync signals are fed to pin1, and pin2 of deflection processor I401 via pin33, pin32 of I501.
With the H. size control signal, the PWM control signal is derived from pin2 of I501 which is fed into a
integration circuit R503, C503 and pull-up resistor R502 and amplifier Q502 to give a DC control voltage
on the collector of Q502.
The CPU is reset when the power cable is re-plug in. The components R506, D506 and C506 on pin4 of
I501 ensure correct start.
The +5V voltage is fed into I501 via pin5, a 8MHz resonator is connected on pin7, pin8 of I501 to generate
the CPU clock for the software execution. There are four input keypads S00 to S04. When a key is
pressed, the corresponding input port will be shorted.
The linearity control signal of horizontal circuit are derived from pin16, pin17, pin20, and pin22 which are
fed to Q402; Q404; Q480 for CS correction and Q489 for linearity C correction.
13

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