Hitachi RAM-71QH5 Service Manual page 59

10. Temperature Detection Circuit
The outdoor units (this model) provides with the outdoor temperature thermistor, DEF (defrost) thermistor,
G
OH (overheat) thermistor and electric expansion valve thermistor so that they detect the temperatures of the
unit and control the system.
The circuit of the thermistors is shown as Fig. 10-1 for model RAM-71QH5 and their roles and temperature
G
measuring points are shown as Table 10-1.
R110: 1.28K‰ – 5%
B100/110:
4400K – 150K
R0: 5.8K‰ – 5%
B0/25: 3400 – 2%
R35: 1.433K‰ – 2%
B0/70: 3400K – 2%
R25: 2.0K‰ – 5%
B25/50: 3500K – 2%
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+ 5V
CN5
CN6
CN7
+ 5V
JW7
R317
JW8
R318
JW9
R319
JW10
R320
JW11
CN8
R321
JW12
R322
JW13
R323
JW14
R324
CN9
0V 0V
Fig. 10-1 Temperature Detection Circuit
+ 5V
C312
0V
IC7
X 2 X
X 1 C
X 0 B
X 5 A
X 6
X 3
X 7
0V
– 68 –
0V