two scc-sg24 have lost excitation voltage

[douwe]

I now have two SCC-SG24 modules that have lost their excitation voltages. One of them is currently at NI being repaired or replaced and in the meantime the loaner they gave me now has the same issue.

My setup is as follows.

PCIe-6351 data acquisition card in my PC

SCC-68 connector board

SCC-SG24 signal conditioning module

Futek LSB302 strain gauge

The problems started showing up after replacing the strain gauge; I used to have an LCM300 which worked fine for several weeks. I'm not sure what is causing the signal conditioners to fail and how could the new strain gauge cause these issues? Even if the strain gauge is shorting out, the SG24's have short circuit and overvoltage protection which should prevent these issues.

I appreciate any help.

[WillPwr]

Hello, Douwe!

This is Will, we spoke on the phone yesterday about this issue as well. Since we determined that your load cell should be within spec, and that the SCC-68 still seems to be working, I am currently investigating other potential causes for the SG-24 failure.

In the mean time, I will allow community members to respond - you can expect to hear from me either today or tomorrow.

Thank you, Douwe!

[Ruben_Morales]

Has there been any resolution found for this issue?  I had 2 strain gauge modules (scc-sg24) lose output excitation (and load down the +/-15 V bus as well) back in October, and we had them fixed while we investigated the problem.  We found a possible exposed wire that could have shorted an excitation line to a 24V line, and since replacing that wire have had no problems.  However, we now have a different set up that utilizes 4 SG-24 modules simultaneously (we use an external 5V 2A switching supply for an external power source to the SCC-68 fixture) and we have had 3 of them lose excitation over the course of a week.  Each was in a different channel at the time (2,3,1 respectively) and even after checking all possible areas for shorts and removing any other signals from the DAQ the module was still damaged.  In each instance, the module would work for roughly an hour before faulting.  The load cells(Sensotec AL111BN) and cables work appropriately with an external meter.  If it makes a difference, both the modules from October and the current failures were from the same shipment.  We have been using these modules extensively throughout our company and have had no problems in other applications before these.  Please let me know if there has been any futher understanding of this.  Thanks.

[douwe]

The resolution for me was to use a different strain gage amplifier (standalone unit from another vendor). We (and NI for that matter) were not able to identify a reason why the SG-24 stopped working and all the components in the system were within the specifications for the SG-24. Due to the unreliable nature of these modules we have stopped using them. That is unfortunate because I do like the functionality the slick integration into the SCC-68 fixture.