# Vacuum leak in PG7601 PG, with or without AMH

Purpose:  Determine if the vacuum leak is coming from the AMH-38 or from the PG7601 and/or piston-cylinder.

Background:  When the vacuum under the bell jar can’t pull down low enough, or if it rises during operation, then it’s possible there could be a leak into the bell jar.  The first step of troubleshooting is to determine if the leak is coming from the AMH-38 or from the PG7601.

Note that you might first clean any sealing surfaces between the PG, bell jar (and AMH-38 if applicable) to try and eliminate leaks.

1. Operate the PG7601 with the glass bell jar but without the AMH-38:
• Keep the mass bell and spindle (the pyramid cone shaped piece) on the piston
• Load one of the 6.4 kg platters onto the mass bell
• Place the bell jar directly down onto the PG7601 vacuum plate
• Manually float the piston using the up/down arrow keys on the PPC4.
• Observe the vacuum value – hold steady, slowing rising??
• Repeat, but with 3 or 4 of the main mass platters
1. Operate the PG7601 with the AMH-38:
• Reinstall the AMH-38 and all of the masses
• Turn power on / off to initialize the AMH-38 with the PG7601 (just make sure the AMH-38 goes through its startup sequence of rising, rotating the columns, firing the pins, and lowering everything back down.
• Apply a vacuum and let it stabilize.
• Manually toggle the following AMH functions and see if the vacuum holds steady for each one or rises:
1. All of the following menu options are located under here: [SPECIAL],<8AMH>,<2control>….
2. Raise the masses: …<1up/down>   observe the vacuum value
3. Lower the masses: …<1up/down>   observe the vacuum value
4. Toggle on each of the binary masses while looking at the vacuum value to see if it goes up or stays the same: …<2discrete>.   You’ll see a screen with “1  2  4  8  16  32”.  Each value represents one of the binary masses.  For example “1” = 100 gram binary mass.  “32” = 3200 gram binary mass.  Use the [+/-] key to enable an asterisk symbol next to the binary mass to load, then press the ENT key to make the load change happen.  Do this for each binary while observing the vacuum value.

Contact Fluke Calibration Technical Support at Pressure Support or call at +1.877.355.3225