Is it possible to burn-out a UMI-7764??

[blax]

I was asked to troubleshoot a system that is using a PXI-7344 and a UMI-7764 to drive a three axis servo system. I noticed that the 5V converter in the system used to supply the UMI had 'blown up'. I disconnected it, and used an seperate power supply to power the UMI with the 5V it requires. There doensn't appear to be short, since only 60 mAs are being drawn from the supply, however the controller won't recognize the differential encoder input to the UMI. I have verified that the encoder information is correct. Is it possible that the UMI circuitry that converts the differential encoder input to a single ended output has been damaged?

[Jochen]

I'm afraid this is possible. The 5V supply is used for powering the circuitry on the UMI and there is no protection circuit for the power supply on the UMI.
Please contact your local NI branch for details about the repair/replacement process

Best regards,

Jochen Klier
Applications Engineering Group Leader
National Instruments Germany GmbH

[AgwaNoa3]

I just want to ask, does that mean that all the encoder inputs are burned out?
And how can I check if the UMI and the NI 7344 are working and not burned out?

[Jochen]

If you haven't tried yet, please connect the encoder signals sequentially to all four encoder inputs and repeat your test. Make sure that the encoder generates signals by using a Scope.

If you don't get the encoder working at any encoder input there is the chance that either the UMI or the 7344 or both components are damaged. In this case there are two options:

1. Contact your local NI branch for a repair request for both components
2. Ask your local NI branch if they can send you a UMI and/or a 7344 as a loan so by exchanging these devices you could find out on your own which device is broken.

Best regards,

Jochen

[Buechsenschuetz]

Even if not all encoder inputs of the UMI box are blown up and some are still functional there is some risk that the remaining ones suffer from damage which will show up in the future.

The inputs of the 734x boards seem well protected (from a hardware designer's point of view). They have protection diodes which will feed any voltage a little over +5V into the supply rail. Maybe your pc power supply will not like this but even I did not manage to damage a 734x board yet.