INFICON HPG400 ATM to High-Vacuum Gauge - Manual (Page 41)

tina31e1 (2004-05) HPG400 v1.om
41
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
4 + 5 ≈37 Ω
>>37
Ω Pirani element 1 broken
5 + 8 ≈37 Ω
>>37
Ω Pirani element 2 broken
1 + 2/6 ≈0.2 Ω
>>0.2
Ω Filament of hot cathode broken
2 + sensor housing ∞
<<
∞ Short circuit electrode to ground
3 + sensor housing ∞
<<
∞ Short circuit electrode to ground
5 + sensor housing ∞
<<
∞ Short circuit electrode to ground
9 + sensor housing ∞
<<
∞ Short circuit electrode to ground
2 + 3 ∞
<<
∞ Short circuit between electrodes
2 + 9 ∞
<<
∞ Short circuit between electrodes
3 + 9 ∞
<<
∞ Short circuit between electrodes
2 + 5 ∞
<<
∞ Short circuit between electrodes
3 + 5 ∞
<<
∞ Short circuit between electrodes
5 + 9 ∞
<<
∞ Short circuit between electrodes
1
2
3
4
5
6
7
8
9
View on sensor pins
Pirani sensor 1 (approx. 37 Ω )
Pirani sensor 2 (approx. 37
Ω
)
Hot cathode (approx. 0.2
Ω
)
Ion collector (IC)
1
Anode (EC)
2
6
3
7
9
4
5
8
All of the above faults can only be remedied by replacing the sensor (
→ 42).
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] and [2]).
For diagnosis of the HPG400-SD (DeviceNet) gauges, the status lights might pro-
duce some useful information (
→ 32).
Troubleshooting (sensor)
Correction
Troubleshooting on
fieldbus gauges
(HPG400-SD, HPG400-SP)