SCXI 1000 gives bad readings

[MPWeber]

I have a scxi 1000 chassis with 3 1140 modules in it. The computer is using a PCI 16E sampling card. We've actually got 3 of these test systems in our lab. One of the systems just started giving us 10V readings on every channel of every module. The 10V readings are showing up in the MAX test panel, so it's not a software bug in our code. I've swapped out the 1140 modules as well as the 1000 chassis, and the error always stays with the one bad chassis.

Any suggestions on further troubleshooting, or do we just need to send this in for repair?

Thanks!

[Matt_A]

Hello MPWeber,

The behavior you indicated could be caused by several things, including damaged hardware. However, before you consider submitting the hardware for repair, I have a couple troubleshooting steps that I would suggest.

First, I would suggest that you make sure that your device is configured correctly. Make sure that the signal reference settings for your DAQ device match the SCXI module. For example, if your device is configured for NRSE, make sure that your SCXI module is also (this may require a jumper setting).

Next, I would recommend that you check out our SCXI Troubleshooting Resource. This page provides several utilities for troubleshooting problems with SCXI and also has several links to other resources.

Finally, could you clarify the behavior to identify what, if anything, could be damaged? Does this behavior seem to follow a certain SCXI-1000 chassis or is it related to a specific SCXI-1140 module? You indicated that you had swapped chassis and modules,  but that the problem persisted on "one bad chassis". Does that mean that all three modules in that chassis produced the 10V reading? Did this inaccuracy seem to be related to a particular slot or set of slots? Have you tried switching the communicating module to see if that has anything to do with it? I apologize for all the questions, but I just want to get as much information as possible.

[MPWeber]

Matt, thanks for the reply.

I checked the jumpers on the 1140 modules, and they are all set to the default differential input which matches the DAQ device.

I looked at your link for SCXI troubleshooting, but didn't find anything that helped.

As to what I've tried: None of the 1140 modules function properly with the one chassis (all channels give 10V on each module). I moved the modules to a different chassis, and they all function properly. I took a working 1140 module from a working chassis, and that module would not function properly in the suspect chassis. I have not tried using a different slot as the communicating module yet, so I will do that next. One other thing that may be worth noting is that I left that chassis on, and couldn't get back to it until this afternoon (1 week later). The chassis and all modules in it were very hot. As I mentioned before, we have 3 of these units and the other two have been working fine, and were on for much longer without heating up hardly at all. I've powered it down for now.

Any other things I should try? Thanks again for the help,

Mark

[Matt_A]

Hello Mark,

Unfortunately, it does sound like there may be some damage to your SCXI-1000 chassis. Based on your description, I suspect the fan may not be cooling the unit properly, but that is just my best guess. You may want to check the fuses to be sure that they are functioning properly, but I'm not sure that will help. There is a document on our website that discusses SCXI Fuse Information. I would also suggest that you go ahead and test another module as the communicating device.

If you decide that you'd like to proceed with a repair, you can contact our support line at 1-866-ASK-MYNI (1-866-275-6964) for help. Any of our Applications Engineers should be able to assist you.

[MPWeber]

Thanks Matt, it was the -10V fuse on the chassis behind the fan. I replaced it and everything is running normal again.

-Mark