Tektronix Technical Forums are maintained by community involvement. Feel free to post questions or respond to questions by other members. Should you require a time-sensitive answer, please contact your local Tektronix support center here.

Overflow error on 4wire measurement

Post Reply
johngtri
Posts: 5
Joined: August 19th, 2015, 11:44 am
Country: United States

Overflow error on 4wire measurement

Post by johngtri » August 19th, 2015, 11:54 am

I need to do low resistance measurements (2.5 milliohms) on a rack of equipment, so I purchased the 5805-12 Kelvin probe set. The cable seems to work fine with an older Keithley DMM, but when I plug it into our 2700 DMM I get an overflow error every time, even if I probe two places on the same piece of metal. Are there any settings I can tweak to make the 2700 start behaving? Could this be a calibration issue (not certain of the cal history on this unit)? Should the 5805 cable set work with the 2700? Any suggestions welcome. Thanks!

Dale C
Keithley Applications
Keithley Applications
Posts: 2848
Joined: June 10th, 2010, 6:22 am
Country: United States
Contact:

Re: Overflow error on 4wire measurement

Post by Dale C » August 20th, 2015, 5:46 am

Hello John,
The Model 5805 will certainly work with the Model 2700 DMM.
One thing I would ask ,
is the front/rear panel switch set to front?
If it is, then what range are you on?
If it is the proper range(100 ohms),
then check the connections.
By this I means there is a disconnect somewhere that is showing as an open circuit.
Hope this helps.

johngtri
Posts: 5
Joined: August 19th, 2015, 11:44 am
Country: United States

Re: Overflow error on 4wire measurement

Post by johngtri » August 20th, 2015, 6:52 am

Thanks for the reply!
Yes, it's set to front. I can do a 2wire measurement using the 5805 probe set, but get the overflow error whenever I set it to 4wire.
I've tried it set to autorange, and I've also tried manually stepping through the ranges down to 100 ohms.
I've tried turning the filter on/off. I tried ocomp. I'm open to any suggestions.
There are no modules installed in the rear (there was a temp module of some sort, but I removed it when I moved the 2700 to try to take measurements.

The equipment is in a secure area, which makes re-calibrating much more burdensome (and I need to get some data quickly).
Are there any reset/calibration steps that an amateur can do?

Thanks again, John

Dale C
Keithley Applications
Keithley Applications
Posts: 2848
Joined: June 10th, 2010, 6:22 am
Country: United States
Contact:

Re: Overflow error on 4wire measurement

Post by Dale C » August 20th, 2015, 8:23 am

Can you short all four terminals on the front panel and see if it is still OVRFLW?
That would tell us if the unit is operating properly.
Then we would look at the 5805 connections.

johngtri
Posts: 5
Joined: August 19th, 2015, 11:44 am
Country: United States

Re: Overflow error on 4wire measurement

Post by johngtri » August 20th, 2015, 10:38 am

I believe I got the same overflow when I shorted all 4 together with regular cables. I'll go try it with the 5805 probe.

I confess that I'm not a guru on the 2700 DMM and much of the manual deals with a 7700 switching module that I don't have installed. Do I need to manually open/close any channels for 4wire measurements?

Andrea C
Keithley Applications
Keithley Applications
Posts: 1294
Joined: October 15th, 2010, 10:35 am
Country: United States
Contact:

Re: Overflow error on 4wire measurement

Post by Andrea C » August 21st, 2015, 5:14 am

What is the model of the older DMM where the test leads are working well?

The 2700 can be used as a general purpose multimeter when using the front panel banana jacks. There is no need to close any relays when using the front panel inputs.

Here is an image for how the 5805 test leads should be plugged into the instrument:
5805_test_leads.png
5805_test_leads.png (60.64 KiB) Viewed 25997 times

johngtri
Posts: 5
Joined: August 19th, 2015, 11:44 am
Country: United States

Re: Overflow error on 4wire measurement

Post by johngtri » August 21st, 2015, 10:37 am

I confirmed that shorting all 4 leads of the 5805 probe still yields an overflow error for 4wire measurement. Not an encouraging sign.

What is the current firmware revision for the 2700? The most recent available for download appears to be B09. I got excited when I noticed that B08 fixed a 4wire error (PR25102) where the sense relays were not closed. I hoped that my firmware revision pre-dated the B08 fix.

But when I checked the firmware rev (during power-up) it said REV: B10 A02.

So is the latest release B10? Why isn't that rev available for download?

Doubt this helps, but it appears that the 2700 was calibrated in April 2013, so it is slightly overdue. If I want to take the unit out of the secure area to be calibrated, would it be bad to restore the firmware to B09 if it's currently at B10?

BTW, the older DMM where the test leads are working well is 196. That'll take you back...

Dale C
Keithley Applications
Keithley Applications
Posts: 2848
Joined: June 10th, 2010, 6:22 am
Country: United States
Contact:

Re: Overflow error on 4wire measurement

Post by Dale C » August 21st, 2015, 10:47 am

I do not believe firmware or calibration would help.
I believe this unit needs to be serviced.
Regards,
Dale

johngtri
Posts: 5
Joined: August 19th, 2015, 11:44 am
Country: United States

Re: Overflow error on 4wire measurement

Post by johngtri » August 21st, 2015, 11:13 am

Rats! All signs point in that direction. Thanks for all of the help!

Post Reply

Return to “Series 2700 Multimeter/Data Aquisition/Switch System”

Who is online

Users browsing this forum: No registered users and 12 guests