6704 current channel out of tolerance

[Matteo_Busani]

Hi to all.
As a company, we own about 10 PCI-6704 equipped in our test equipment.

Over the years, some have highlighted specific malfunctions on a single current channel (never the same one), in other words, breakages. It happened that the current read was slightly lower than the set one, but well out of tolerance.

Without electrical diagrams, only with the multimeter, I was able to identify each single current output stage (also voltage). By carefully comparing the faulty one with the working one, I found that the one that breaks down is always a small p-mos transistor that is directly connected to the output.

I am writing this post for everlasting memory, for those who should encounter the same problem.

The p-mos in question are marked with "T50xx" (where xxx are other characters that vary depending on the production batch) for most of the cards analyzed but it can also change, they are close to the operational amplifiers marked with "T064". They are p-mos TP0610T-G.

Available for further clarifications.

[santo_13]

Have you tried identifying the external connection to the channel that is failing the most? Why would just that channel fail when the parts/circuit are the same across other channels?

Are you calibrating the DAQ at the recommended intervals to offset this degradation?

https://knowledge.ni.com/KnowledgeArticleDetails?id=kA03q000000x1xHCAQ&l=en-US

Looks like you don't need an external calibration in most cases

[Matteo_Busani]

Broken channel is not always the same, since my cards are employed in several ATEs. Maybe it's a static discharge problem...

It's not a calibration problem. I checked the pmos are actually broken and replacing them the channel returns to work perfectly.

Thanks for interest

[santo_13]

Current surges, grounding, ESD are some of the causes of random component failure and moreover as you say the damaged channel is not consistent across ATEs, it would be nice if you can find what is common among the channels that failed, like the type of circuit those channels connect to or something that allows you to get to the root cause.