Fluke 5520A Zero Cal

[regor]

We have one of our 5520A calibrators failing "Zero Cal" but, it passes "Full Cal". Has anyone ran into this? Thanks for your time and /or suggestions.

[measure]

Under "CAL," the 5520A has a "ZERO" function and an "OHMS ZERO" function. The former performs a 'full' zero, required every 7 days, where the latter, a subset of the "ZERO" operation, is required every 12 hours. Theoretically, if the unit passes the full zero, it must also pass the ohms zero. Can you be more explicit? Thanks.

[USMCPMEL]

I have had mine fail from time to time. I would just re run it and usually it passes on the second attempt.

[Ronin]

You've probably already found the answer to this, but as I remember it, there is a requirement to short the input before initiation right? So, that being said, there were many times when the low-thermal short was to blame (Pomona style shorts have a way of getting swapped out with Pomona style loads.  If you are using copper wire, use a larger gauge and make sure exposed tips are burnished. Beware of using copper wire though.  Your zeros will not have accounted for any contaminants inside the input terminals. Cheers!

[NavyCalMaster]

Not sure if you fixed your problem yet, but we recently had the same problem and sent the calibrator to Fluke.  Apparently there is a software issue and they fixed it at no charge.

[regor]

I wasn't as lucky with the no charge thing. We apparently had a defective A7 board which was replaced. First repair on this 5520A, 8 years old, so I guess I can't complain.

Thank you for everyone's input.

[McDobber]

On the 5500A/5520A, once you start seeing any error codes coming up when you attempt to Zero them, there is a bigger issue that needs to be addressed ASAP.  Either fix it or send it to Fluke.  Hope this helps.