NEC MultiSync FP1355 FP1355 FP1355, Руководство по обслуживанию

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Moreover, if pin 39 PRO 1 signal is at HI for 1 second or more, it will be regarded as a short
circuit of the power of the secondary side to forcibly turn ON POWER SAVE in order to
prevent trouble from being escalated.
1.6.5 ABL, Beam Protector
The feedback signal ABL of the beam current is input into MPU IC101 pin 16.
In case the signal ABL exceeds the voltage level given below, the contrast setting of the preamplifier
IC211 is lowered down to prevent the excessive flow of the beam current.
ABL specified voltage: {5 * (OSD item ABL) / 256} (V)
Further, in case the signal ABL exceeds the 4.7 V level continuously for 2 seconds or more, the situation
is judged as circuit error, bringing the system forcibly to POWER SAVE mode.
1.6.6 CRT support
(1) Geomagnetism
The voltage conversion signal of horizontal magnetic field is output from pin 2 of the Geo-
magnetism sensor IC214, and the one of vertical magnetic filed is output from pin 1 of the
Geomagnetism sensor IC214. These are buffered or reversed and amplified by IC103
operational amplifier, and input to A/D converter of pins 18 and 19 of microcomputer
IC101. These signals are converted to digital values, and the Geomagnetism around the
monitor is detected.
(2) Temperature
The signal that divides the 5V at the thermistor TH100, R136 and R137 is input
into the A/D converter of MPU IC101 pin 14 and converted into digital value. Thus, the
temperature inside the monitor is detected.
(3) ON time
The monitor ON time signal BEAM TIME is input into the A/D converter of MPU IC101 pin
15 and converted into digital signal to detect the monitor ON time.
In order to cancel the deterioration in purity and convergence due to the aforesaid in (1) ~
(3) geomagnetism, temperature and variation with time, the cancel current is passed to
each C_PURITY 4V coil.
Each C_PURITY ROTATION controls the PWM DAC output (pin 3 and pin 6 to pin 9) of
MPU IC101 by means of the signal smoothened by R and C.
The digital signal transmitted to the deflection processor IC601 from the microcomputer
through I2C bus and converted into analog voltage by IC601 is output from pin 60 then it
controls the convergence 4V.
1.6.7 High voltage control
The high output voltage control is carried out by means of HV-ADJ signal smoothening the PWM DAC
output of the microcomputer MPU IC101 pin 1 using R133 and C114.
The high voltage feedback signal X-PRO is input into the A/D converter of MPU IC101 pin 17. When this
voltage exceeds the specified level for 600 msec or more, the situation is regarded as high voltage error,
setting the monitor to POWER SAVE mode.
The specified voltage level is obtained from {5 * (OSD item XPRO LEVEL) / 256} (V)