PSN-L Email List Message

Subject: Re: Haunted system misbehaving again
From: Geoffrey Voeth gmvoeth@...........
Date: Wed, 20 Jun 2012 09:23:56 +0000


On 6/19/2012 6:54 PM, Larry Conklin wrote:
> I have an SG sensor that has intermittently had serious noise problems,
> literally for years. Mechanically, it is very similar to the design that
> is shown on Larry's PSN web site, and it uses Larry's electronics board,
> which I believe he is no longer selling.
>
> When the thing is running properly I've been quite happy with it. But
> occasionally, for reasons I have never been able to pin down, it
> exhibits extreme low frequency noise, to the point where it is basically
> useless. The current episode began with the system running very well,
> but it was in need of leveling, which I've typically need to do every
> couple of weeks or so. Before I adjusted the leveling screw, it was
> quiet. After messing with it it became extremely noisy. So, you'd
> believe that it was some sort of mechanical problem, right? And I've had
> several other episodes that began the same way. This time, when I
> brought it upstairs on the bench, I did in fact discover that the lock
> nut on the leveling screw was loose, and I "fixed" the problem by
> re-tightening it. Ran pretty well for a week or so thereafter, but not
> really as quiet as it should be. Then, it spontaneously got quite noisy
> again, interspersed with periods where it ran ok.
>
> I have a lot of other history with seemingly mutually exclusive
> symptoms/probable causes, but the bottom line is I don't have a clue
> what is really going on. I'm tempted to believe that there is something
> subtle wrong with the electronics board, but in past attempts to trouble
> shoot it, haven't been able to find anything.
>
> If there is anyone out there who has one of Larry's SG boards that
> they're willing to part with, I'd be interested in buying it. If for no
> other reason than to rule out the board as the source of the problem.
>
> For the curious, I have a little web page that I dump drum reports up to
> daily. The report for today (so far) shows a particularly noisy day, but
> does include the quake that happened in the Aleutians this afternoon.
> The page also shows drum reports from the day this round of the problem
> started. The day started just fine, until the big transient that
> resulted when I went down and adjusted the leveling, at which point all
> hell broke loose. You can also see the consequences of two subsequent
> leveling adjustments later in the day. After that data was recorded, I
> didn't mess with the thing for maybe a week, until I finally got around
> to taking a closer look at it, at which point I realized that the
> leveling screw was loose and re-tightened it.
>
> I'd be very interested in anyone's thoughts on this problem. The link to
> my web page follows:
>
> http://home.roadrunner.com/~lwconklin/
>
> Larry Conklin
> Liverpool, NY
>
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>

The troubles I have had with unstable electronics seem to be related
to shielding and bonding and RFI and Heat and Cold.
Possibly try surrounding the electronics with jugs of water
to help stabilize the temperature or filtering the signal
to eliminate the ultra low frequency components.
There is a new problem I have recently had with seriel communications,
something unknown to me is interrupting the flow between
the computer and the A/D converter. I think it is the computer itself
but do not know how to prove it since so much unconyrollable
stuff is going on.

geoff

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