Date: Fri, 24 Jan 2020 18:18:07 +0000
Marc,
I think it is often the case that a capacitor in the power supply of 80 MHz signal is bad. If you can test the caps, you will probably find the leaky one. We had a DRX600 at MIT when I was there that suffered this type of failure, as I recall. Either 60 or 120 Hz spikes or loss of phase coherence (80 MHz sinusoid randomly starts over due to a triggering issue associated with voltage drops). My guess as to this being the culprit, about 80-90% certainty. Could still be due to something else. In these older consoles, the large capacitors in the power supply fail on a regular basis. Good luck.
Jeff
From: ter Horst, Marc A. <terhorst_at_email.unc.edu>
Sent: Thursday, January 23, 2020 4:18 PM
To: ammrl_at_ammrl.org
Subject: AMMRL: 80MHz output on a DMX spectrometer
Hello
Some of you may remember Bruker spectrometers before the AVANCE series. We have a DMX console that has been our bread and butter solids instrument. Unfortunately the old timer in the lab (the spectrometer not me) is no longer working correctly. While trying to tune the probe, an error indicates a problem with the 80MHz input at the TCU and the 40MHz input at the RCU. The problem actually stems from an unstable 80MHz output at the PTS. When an external 80MHz source is used, the error no longer pops up. However, the spectrometer is still unable to tune- that is the wobble curve is a 'spikey mess'.
Those of you with a better understanding... is there a way to synchronize an external 80MHz source with the spectrometer and possibly avoid buying a replacement PTS?
I'm also on the lookout for used PTS D620. :)
Marc
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Marc ter Horst, PhD
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