Jon,
Get out the specifications for the geophones and look-up the coil and shunt (if installed) resistance. The coil should be 150, 240 or 380 ohms and the shunt may be 0, 4133, 2739, or 1992 ohms (per Larry Cochrane's posted specs). Remember, the resistances are in parallel so you'll have to do some number crunching to compute the theoretical resistance.

Now disconnect the wires at the terminal board and, using a multimeter, check the resistance of the three geophones. If the resistance on the east-west sensor is zero then you've got a broken connection. If the resistance is substantially different from the specifications (your calculations and the other two geophones) then you've probably got a bad connection or a short. If the resistance is proper, then the east-west geophone is probably tilted off-axis (unlikely if the others are functioning properly). If you didn't solder your connections, you must do so or you will have recurring problems.

Jon, what ever happened with the ground movement (landslide) that started to show-up at your folk's farm?

Regards,
-Tim-

-------------- Original message from Jón Frímann : -------------- 


> Hi all 
> 
> I have noticed that the channels on the geophone downt show the same 
> level of noise as I am execting. For instance, now is the North-south 
> channel showing normal noise leve, also the vertical channel, but the 
> east-west channel is relative quiet. Just before that the north-south 
> channel was the quieter one. 
> 
> Far as I can tell, the cable is fine and properly connected. I did check 
> the connection to the geophone (I use rc connection type of connect to 
> the geophone, prior to that there is ~1m long cable from the geophone, 
> that is also in good condision.) and it appears to be fine. 
> 
> Before I started to seal the seismomter vault better, all channels where 
> showing simular level of noise. But now the east-west channel is 
> completly flat. 
> 
> What might be the issue ? 
> 
> Regards. 
> -- 
> Jón Frímann 
> http://www.jonfr.com 
> http://www.simnet.is/jonfr500/earthquake/ 
> 
> __________________________________________________________ 
> 
> Public Seismic Network Mailing List (PSN-L) 
> 
> To leave this list email PSN-L-REQUEST@.............. with 
> the body of the message (first line only): unsubscribe 






Jon,
Get out the specifications for the geophones and look-up the coil and shunt (if installed) resistance. The coil should be 150, 240 or 380 ohms and the shunt may be 0, 4133, 2739, or 1992 ohms (per Larry Cochrane's posted specs). Remember, the resistances are in parallel so you'll have to do some number crunching to compute the theoretical resistance.
 
Now disconnect the wires at the terminal board and, using a multimeter, check the resistance of the three geophones. If the resistance on the east-west sensor is zero then you've got a broken connection. If the resistance is substantially different from the specifications (your calculations and the other two geophones) then you've probably got a bad connection or a short. If the resistance is proper, then the east-west geophone is probably tilted off-axis (unlikely if the others are functioning properly). If you didn't solder your connections, you must do so or you will have recurring problems.
 
Jon, what ever happened with the ground movement (landslide) that started to show-up at your folk's farm?
 
Regards,
-Tim-

-------------- Original message from Jón Frímann <jonfr500@.........>: -------------- 


> Hi all 
> 
> I have noticed that the channels on the geophone downt show the same 
> level of noise as I am execting. For instance, now is the North-south 
> channel showing normal noise leve, also the vertical channel, but the 
> east-west channel is relative quiet. Just before that the north-south 
> channel was the quieter one. 
> 
> Far as I can tell, the cable is fine and properly connected. I did check 
> the connection to the geophone (I use rc connection type of connect to 
> the geophone, prior to that there is ~1m long cable from the geophone, 
> that is also in good condision.) and it appears to be fine. 
> 
> Before I started to seal the seismomter vault better, all channels where 
> showing si
mular level of noise. But now the east-west channel is 
> completly flat. 
> 
> What might be the issue ? 
> 
> Regards. 
> -- 
> Jón Frímann 
> http://www.jonfr.com 
> http://www.simnet.is/jonfr500/earthquake/ 
> 
> __________________________________________________________ 
> 
> Public Seismic Network Mailing List (PSN-L) 
> 
> To leave this list email PSN-L-REQUEST@.............. with 
> the body of the message (first line only): unsubscribe 
> See http://www.seismicnet.com/maillist.html for more information.