INFICON BCG450 ATM to Ultra-High Vacuum Triple Gauge - Manual (Page 48)

48
tina40e1-b (2011-04)
If the cause of a fault is suspected to be in the sensor, the following checks can be
made with an ohmmeter (the vacuum system need not be vented for this purpose).
Separate the sensor from the electronics unit (
→ 15). Using an ohmmeter, make
the following measurements on the contact pins.
Ohmmeter measure-
ment between pins
Possible cause
2 + 4 ≈37 Ω >>37 Ω Pirani element 1 broken
4 + 5 ≈37 Ω >>37 Ω Pirani element 2 broken
6 + 7 ≈0.15 Ω >>0.15 Ω Filament of hot cathode broken
4 + 10 ∞ <<∞ Electrode - short circuit to ground
6 + 10 ∞ << ∞ Electrode - short circuit to ground
3 + 10 ∞ << ∞ Electrode - short circuit to ground
9 + 10 ∞ << ∞ Electrode - short circuit to ground
6 + 3 ∞ << ∞ Short circuit between electrodes
9 + 3 ∞ << ∞ Short circuit between electrodes
All unmarked pins in the diagram are used by the diaphragm sensor
electronics and cannot be utilized for diagnostic purposes (do not con-
nect an ohm meter/continuity checker to these pins).
Hot cathode ca. 0.15 Ohm
Ion collector
Pirani sensor 1 ca. 37 Ohm
Pirani sensor 2 ca. 37 Ohm
6
7
8
2
4
5
3
10
9
Anode
Not connected
GND (connected to sensor housing)
7
2
3
4
5
6
10
View on sensor pins
All of the above faults can only be remedied by replacing the sensor ( → 49).
Error diagnosis of fieldbus gauges can only be performed as described above for
the basic sensor and sensor electronics. Diagnosis of the fieldbus interface can
only be done via the superset bus controller (
→ [1], [2]).
For diagnosis of the BCG450-SD (DeviceNet) gauges, the status lights might pro-
duce some useful information (
→ 39).
Troubleshooting (sensor)
Correction
Troubleshooting on
Fieldbus Gauges
(BCG450-SD, -SP)