NEC MultiSync FP1370 Service Manual page 185

1-B) SENSOR OF TEMPERATURE CIRCUIT
Temperature Sensor (IC151) is used in this circuit.(on CONTROL PWB)
When the surrounding temperature of the unit change, the voltage of IC151 out put pin (CNCL 16pin on
VIDEO PWB) varies.
This voltage is fed to the A/D converter in IC801 (pin50)
1-C) SENSOR OF CRT BEAM CURRENT CIRCUIT
Change of purity is caused by warm up after power on and changing of CRT beam current.
Correction voltage is generated by charging C4P1. This voltage can detect both warm up and changing of
CRT beam current. Warm up is detected by C4P1 charging time, changing of CRT beam current is detected
by changing of ABL voltage. Correction voltage is input to IC801 pin 51. IC801 calculates four corner purity
correction. Q4P2 is switch in PMS and power off. Q4P4 is buffer of correction voltage.
+12V
R4PF
Q4P3
R4PH
1000
800
600
400
200
0
20
Temperature (℃)
(Fig.10.2) The example of Temperature sensor (IC4H1) voltage
R4P9 R4P8
R4P1
Q4P1
R4PA
R4PE
MD4P1
Q4P2
C4P1
R4P5
R4P4
+12V
(Fig.10.3) Sensor of CRT beam current circuit
40 60
80
ABL Voltage
S5V
+12V
D4P1
MD4P2
Q4P4
R4P7
8-60
100
IC801
51
CPU