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keithley 7002 switch system current leakage

7001, 7002 and Switch Cards
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claire
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Country: United States

keithley 7002 switch system current leakage

Post by claire » April 25th, 2011, 6:03 pm

Hi there,

The current of Keithley 7002 output channel is ~3 nA as applying 10 V even if no input channel is connected. The card type is Keithley 7012. The same test is run on Keithley 7001 main frame and only <1pA is observed. I wonder if Keithley 7002 has a greater current leakage. Is there any way I can reduce it? Thanks.

Dale C
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Re: keithley 7002 switch system current leakage

Post by Dale C » April 26th, 2011, 8:58 am

What procedure did you use to measure the leakage?
I used the "Offset Current" test on page 5-4 in the instruction manual.
I have measured both the 7002 and 7001 with a 7012-S card installed.
The leakage current on both units is less than 1pA.
I used the procedure found in the Model 7012-S instruction manual.
Maybe there is something wrong with the 7002?

claire
Posts: 8
Joined: November 30th, 2010, 3:45 pm
Country: United States

Re: keithley 7002 switch system current leakage

Post by claire » April 26th, 2011, 10:05 am

My set up is similar to the one in Fig. 5-3, the differential current leakage test. Keithley 236 SMU is connected to switch card output instead of Keithley 617. The 7002 switch mainframe is powered off. When I apply a 10 V using Keithley 236, I get about 3 nA current. This means the open resistance is not zero. The same test with 7001 switch mainframe only show about 1 pA current leakage.

So this has something to do with the mainframe 7002. Not sure if this has something to do with backplane row jumper...

Dale C
Keithley Applications
Keithley Applications
Posts: 2849
Joined: June 10th, 2010, 6:22 am
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Re: keithley 7002 switch system current leakage

Post by Dale C » April 26th, 2011, 10:51 am

I have tried this with a 236 for measurement.
The backplane jumpers in and out.
I read around 3pA with the Model 236 set to 10V and a compliance of 1nA.
Something is pointing to the 7002 for high leakage.

claire
Posts: 8
Joined: November 30th, 2010, 3:45 pm
Country: United States

Re: keithley 7002 switch system current leakage

Post by claire » April 26th, 2011, 11:11 am

You tried both with and without the jumpers and it does not make difference, right?

I wonder how many 7012S cards you put in 7002? Thanks!

Dale C
Keithley Applications
Keithley Applications
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Joined: June 10th, 2010, 6:22 am
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Re: keithley 7002 switch system current leakage

Post by Dale C » April 26th, 2011, 11:38 am

I put one 7012-s card into the 7002.
It also had two 7053 cards. That is just the way I found the unit so I did not bother it.

claire
Posts: 8
Joined: November 30th, 2010, 3:45 pm
Country: United States

Re: keithley 7002 switch system current leakage

Post by claire » April 27th, 2011, 11:44 am

Can you suggest a way to reduce the leaking current of mainframe 7002? Is it ok to wash the board with soap water and bake it up? Thanks!

Dale C
Keithley Applications
Keithley Applications
Posts: 2849
Joined: June 10th, 2010, 6:22 am
Country: United States
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Re: keithley 7002 switch system current leakage

Post by Dale C » April 28th, 2011, 7:23 am

Clean connectors are one way to be sure the minimize leakage.
Try cleaning the card and backplane connectors with G3 from Gen Solve. Search on G3 on web to find.
It is a Gen Solve product that is environmentally friendly.
Other than that I recommend sending the unit to KI for evaluation and service.

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