Hello Everyone;
Last weekend the large UPS "protecting" 7 spectrometers (and other equipment) failed, and everything crashed.
When I brought our Inova 500 back up on Monday I found large 120 Hz sidebands in a proton spectrum (the doped
H2O/D2O standard). There aren't any sidebands in a 13C 1d, but there are in a 19F spectrum. We have been
checking the signals with an oscilloscope and don't find anything in the transmit path. We can't see anything in
the input to the receiver (although this may be for instrumental reasons), but we do see the 120 Hz glitch in the
output of the receiver. We swapped the receiver, but they are still there. We've also tried swapping the PTS,
the attenuator/switch, the high-band preamp, the mixer, and the cables between the probe and the preamp and
between the preamp and the mixer, but nothing helps. The DC voltages on the front of the power supply seem okay,
and we've tried to use the oscilloscope to see if we can see anything on top of them, but can't (again maybe for
instrumental reasons). We're running out of ideas; does anyone have any suggestions?
Thanks,
Karl Koshlap
UNC Eshelman School of Pharmacy
P.S. Swapping the power supply looks like it would be a major project!
Received on Wed Nov 12 2014 - 14:30:50 MST