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Transpector MPH Operating Manual
6.5.2  How to Determine if a Filament Kit Replacement is Required
Follow these steps to determine if a filament replacement is required. Remember 
that Transpector MPH has dual filaments, so if one filament is blown, but the 
second filament is intact, Transpector MPH can still be used with the second 
filament.
NOTE: Performance of the second filament may be impacted by previous use of 
Transpector MPH.
1 Measure the resistance of each filament. This can be accomplished while the 
sensor is under vacuum by measuring the resistance between pins 3 and 10 
for filament 1 and pins 4 and 10 for filament 2 (see Figure 6-1 on page 6-5). A 
failed filament will measure open while an intact filament will measure 0.8 
Figure 6-1  Sensor pinout
Table 6-2  Pin assignment
Pin Assignment Pin Assignment
1PP8GND
2EM HV9 RF+
3 Filament 1 10 Filament Common
4 Filament 2 11 Reserved
5 Anode 12 Focus
6 RF- 13 TP
7GND