5-18 Chapter 5: Testing SHB_U14
Sensor-CPU circuit board
Accessories
Multimeter
Preface
Always replace a defective Sensor-CPU board.
The following test can be performed to determine which function is defective.
Visual check • LEDs
• H1 green → 24 V power supply OK
• H2 yellow → Thermostat temperature still outside limits
• H3 red → Defective Sensor-CPU circuit board
Normal condition: LED lights shortly after the analyzer module is
turned on.
• SMD fuses
• F1 0.2 A → 24 V power for solenoid 1 "......."
• F2 3.15 A → 24 V power for thermostat heater
• F3 3.15 A → 24 V power for internal pump
• F4 0.2 A → 24 V power for solenoid 2 "......."
• F5 0.2 A → 24 V power for solenoid 3 "......."
Electrical value
Voltage
Where? Sensor-CPU circuit board, plugs X8 and X10
Desired value
Function Plug Pin Desired value
Off On
Heater X 8 1 ↔ 2 0 V 24 V intermitt.
Pump X10 2 ↔ 3 0 V 0-24 V
Solenoid 1 X10 5 ↔ 6 0 V 24 V
Solenoid 2 X10 7 ↔ 8 0 V 24 V
Solenoid 3 X10 9 ↔ 10 0 V 24 V
Flow detector
Internal gas lines
X10 17 ↔ 20 (⊥)
18 ↔ 20 (⊥)
+ 15 V
- 15 V
Fortsetzung auf der folgenden Seite
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