ViewSonic P90F Service Manual page 19

When the sync signals are both exist, then IA01 will send Low at pin 13 to switch on the relay
BR801 via Q104 and Q104A and thus produce a very high current circulate the degaussing coil
and this signal will sustain for a certain period. Thus the display is demagnetized
The sync signals are buffered by IA01 and output at pin 41, 42 to synchronize the timebase
controller I301. IA01 will also initiate I301 by IIC bus build by pin 28(C.SCL), pin 27(C.SDA).
This IIC bus is also responsible to initiate the video pre-amplifier I901and OSD I903. After the
initiation is completed I301, I901 and I903 will operate normally. This IIC bus also provides
Purity control, through P421, connect to PWB-0417, purity control board.
Pin 17 to pin 20 and pin32 provide the logic to control the horizontal CS linear correction circuit
according to the horizontal frequency range as the following table.
P90f CS Table
HS
MCU Pin
Capacitor
Hf <32KHz
32KHz<Hf<=36KHz
36KHz<Hf<=40KHz
40KHz<Hf<=45KHz
45KHz<Hf<=52KHz
52KHz<Hf<=58KHz
58KHz<Hf<=65KHz
65KHz<Hf<=70KHz
70KHz<Hf<=86KHz
86KHz<Hf<=96KHz
Hf>96KHz
Pin 36 (F/V) provides horizontal C linearity control.
Pin 40 provide rotation PWM to rotation circuit build by Q701, Q702 and Q703 and thus control
the current circulate the coil around the deflection yoke to rotate the display.
Pin 1 provide Horizontal convergence control through Q426,Q427, Q428.
Pin39 provide Vertical convergence control through Q305, Q306, Q307.
Pin 31 short to ground via 15pin D sub connector when it connect to PC. When it is
disconnected, power saving feature is switch off, monitor will display "NO SIGNAL" as self test
pattern.
2
IA02 is E PROM for IA01 to save settings of all modes and DDC data.
8-3 TIMEBASE CIRCUIT
8-3-1 TIMEBASE CONTROL (I301), HORIZONTAL
I301 is an IIC control Time-base processor, By IIC bus pin30, 31(SDA,SCL) it can communicate
with IA01(MCU)
ViewSonic Corporation
CS
CS4
32
C425
H
H
H
L
L
L
L
L
L
L
L
CS3 CS2
17 18
C421 C420
H H
H L
H L
H H
L H
L H
H L
L L
H L
H L
L L
15
Confidential – Do Not Copy
CS1 CS0
19 20
C419 C423
H H
H L
L L
H H
L H
L L
H H
H L
L H
L L
L L
P90f-1