Our aging Varian MR400 has developed a nasty problem. There seems to
be 60 Hz A/C leaking across the ground. I can detect it on the rack and and
any non-painted metal surface in the console. The MR400 design has the
console power supply, generation of all DC voltage, Shim power supply, and
both RF amplifiers in one unit. With only that unit powered, and no
connections to the rest of the console, I can detect a 100 mVpp 60 hz signal
if connected to the INPUT of the rf amplifiers. Comparing this to another
aging VNMRS console, only 5 mV pp A/C is observed. The issue with our MR400 is
bad enough that the amplifiers indicate they are in CW mode at all times.
Visual inspection shows nothing "burnt out".
Has anyone run into this issue? Are there any usual suspects to look
at in hopes of determining what has gone wrong to create this issue?
Thank you,
Brian
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Received on Tue Mar 05 2024 - 10:21:00 MST