On a recent job, I noticed traces going dead during the day for no apparent reason.
Although it is not uncommon to see the occasional intermittent trace, this was occurring too often for my liking.
Luckily, SMRefract includes a database facility that can provide a history of bad stations.
What I saw was traces that were repeatedly intermittent.
A bit of investigation in the field revealed that FDU pins were breaking off inside the molding. It usually wasn’t obvious until the pin was actually wiggled, although in some cases the pin would pull
out when the geophone string was disconnected.
Even more entertaining was that some of the troubleshooters were well aware of the problem and instead of changing the link, would insert a piece of wire or solder into the female pin of the geophone string to ‘fix’ the station.
Quite a creative idea, but it just meant that bad equipment rolled to the front, requiring it to be fixed again in the future. It also meant that geophone strings with a blocked female pin would (attempt to) be connected to good FDUs, likely damaging them too.
I found that using SMRefract to detect these stations was practical, but a bit tedious, so have made some major changes in the Database dialog. There is now an ‘Output List’ where you can add traces you want to look at, and you can output Garmin or KML files that can be directly uploaded to a GPS if you want to go look at them.
Another new feature added is that FDUs that fail for the same fault at different locations can now be listed.
This enhances the ability to detect the FDUs with broken pins, and it will also allow you to detect FDUs that repeatedly fail tilt/leakage/resistance inexplicably and FDUs that perhaps show up as noisy more often than they should. Furthermore it allows you to see if bad equipment has in fact been removed from the line.
Here we see an FDU that had been checked and found to be bad (by me) and the recorder notified
And here the same FDU failing for the same fault a few weeks later at the front, meaning it was not changed when I asked.
Details of changes will in the manual in a few days.