2000, 2001, 2002, 2010, 2100, 2110
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Joined: August 26th, 2015, 11:33 am
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Post by Irmantas » August 26th, 2015, 11:37 am


I am using Keithley 2000 DMM. I am controlling and reading values with VB code from PC. Measuring voltage 2 times (waiting for some time and again measuring 2 values etc.), first value is around 70mV and second value should be around 2V or more, but DMM can't read this value, it shows OVERFLOW error.
I 've tried everything - changed range 1V/10V/100V ; changed reading speed; changed AUTORANGE ON or OFF, auto zero ON/OFF.... nothing helps. DMM shows that for example range or speed was changed and again jumps to auto range and shows OVERFLOW...

Another strange thing is that this software and DMM works perfectly with other measurements (same reading 2 values, waiting for some time and again reading 2 values and etc. ) then voltage level are pretty same first value 70mV second value 89mV, or first value 9.98V , second value 10.08V.

Could you help me to solve this problem?

Best Regards,

Dale C
Keithley Applications
Keithley Applications
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Re: OVERFLOW error

Post by Dale C » August 26th, 2015, 11:50 am

Sounds like this unit has some service issues.
It is very straight forward to make voltage measurement with the Model 2000.
Autoranging can slow things down, but should eventually show the proper reading.
Obviously if you are on the 100mV and try to read 7V it will read overflow.
Have you checked the front/rear panel switch?
Maybe it is semi contacting? Just exercise it by pushing it in and out a couple of times.
Not sure that would help., but you never know.
What is the rate you are measuring at?
I would think 100msec between readings would be sufficient, depending on how the instrument is configured.

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thermocouple type in Keithley 3706A

Post by Carlos17 » September 1st, 2017, 8:26 am

Hi every one,
I am a new user of a Keithley 3706A. I am trying to perform a simple temperature measurement by using a thermocouple type T. After connecting my T thermocouple to the 3720-ST terminal block and following the procedure given in the "3706A User's Manual" page 5-60 (T type thermocouple and internal reference junction are selected), the Keithley displays a temperature value on the front panel. Problem is, on the "Measurement function attributes" of the Keithley it's indicated that I am using a K_T/C (default type) not a T_T/C, does anyone know why?

My second question: is it possible to change the default thermocouple for temperature measurement in a given channel from K type to T type? If yes, How to do it?

Thank you in advance for the help


Alex Bitman
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Joined: March 16th, 2018, 5:40 am
Country: Great Britain

Re: OVERFLOW error

Post by Alex Bitman » March 16th, 2018, 6:23 am

Some time ago I was repairing Keithley 2000 and Keithley 2700 DMMs.
Both have defective LM339 (quad comparator) which controls FET switches.
Both units had small holes in LM339.
After replacement, both units worked just fine (checked on all ranges).
But how did the failure happened? All surrounding circuits are working fine...
I have only two ideas: defective series of IC's or overvoltage on -15V, +5 lines powering the comparator...
Cheers, Alex Bitman

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