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Message ID: 653     Entry time: Fri Oct 10 14:40:23 2025
Author: Xuesi Ma 
Type: Update 
Category: VAC 
Subject: Pressure gauge Swap 

[Tyler, Ma]

We suspect a pressure gauge problem. The electronic unit of the main chamber pressure gauge and the electronic unit of the RGA chamber pressure gauge are swapped.

Power and current draw aren't high for the turbo pump.

Before opening the gate valve, the pressure in the Main chamber is 2.98e-8 Torr, RGA Chamber 1.21e-5 Torr

After opening the gate valve (not fully open), the pressure in the Main chamber is 2.97e-8 Torr, RGA Chamber 1.55e-9 Torr. Note: the HV sensor suddenly turned on and the reading jumped to -9 Torr

Opening the gate valve a bit more, the pressure in the Main chamber is 2.98e-8 Torr, RGA Chamber 1.34e-9 Torr.

After switching the electronic unit, the pressure in the Main chamber is 3.23e-8 Torr, RGA Chamber 1.43e-9 Torr.

Gate Valve fully opened at 16:01 Oct 24, 2025

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