2000 self test fail 306.2

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Macduff
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Country: United Kingdom

2000 self test fail 306.2

Post by Macduff » November 14th, 2015, 2:02 pm

Hi, I recently upgraded the firmware of my 2000 from A06 to A15 and on running the built-in test found it failed with 306.2 "INPUT BIAS I"

From searching this forum it appears to be something to do with leakage.

I switched back to A06 firmware and everything runs ok as there is no 306 check in that self test. There is no mention of 306 in the Repair Manual (2000-902-01 / Rev B. March 1997). It only goes up to test 304 in the 300 test bank. Is there any more up to date repair manual or an addenda available?

For what it's worth all the other tests in this series pass, and examining the results from single step I get:

306.1: 6.950002
306.2: 6.948757 (fail)
306.3: -0.001200
306.4: 0.037071

Also regarding firmware, is version A18 as mentioned in the Calibration Manual (2000-905-01 / Rev F. August 2007) available? I have a copy of A20 but apparently a factory recalibration is needed for firmware A19+ and I don't want to go there!

brian.d.smith
Keithley Applications
Keithley Applications
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Re: 2000 self test fail 306.2

Post by brian.d.smith » November 16th, 2015, 11:07 am

I traded email with someone in our service organization.
This error can happen when relative humidity is too high. Try to dry out the 2000 and operate it in lower humidity.

Below is a description of error 306.2 My recommendation is to clean the PCB area around the components with Isopropyl alcohol listed below and clean the components. See if this cleaning eliminates the error. pA level errors can be induced by finger oil smudges on circuit boards.

#Start#306#2
The +7V reference is switched to REFBOOT. This +7V,
which is used as the ohms circuit as a voltage
reference, is switched by U133 pins 2 to 3 (/7V control
line low) to op amp U123 unity gain buffer. +7V now appears
as REFBOOT and is routed through R272, Q109 (/HIOHM control
line is low), the 9.9M half of R117, R115, Q101, Q102, K101 pins 3
to 4 (/RESETK2 control line is high), R304, Q104 (LOV control
line is high) to U113 BUFCOM. To actually calculate
the bias current use the formula;

Bias current in pA = (306.2 reading - 306.1 reading) / 9.9E6

Macduff
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Country: United Kingdom

Re: 2000 self test fail 306.2

Post by Macduff » November 18th, 2015, 4:51 am

Thanks Brian. It's entirely likely I have left some fingerprints within the guarded analog area as I previously replaced a faulty component there. I just never had any issues with firmware A06 because it doesn't have the 306 tests. Humidity here is around 55-60% so I don't think its that. I will get out the IPA and cotton buds.

Is it possible to email me version A18? I tried A20 after backing up the calibration EEPROM but for some reason my meter just lit up all the segments on the VFD and hung. Perhaps I have a dodgy copy of A20, or maybe I need to somehow do a factory reset and full calibration. So I figure A18 would be best for me until I eventually clear all faults and take it for a proper cal/adjustment.

brian.d.smith
Keithley Applications
Keithley Applications
Posts: 389
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Re: 2000 self test fail 306.2

Post by brian.d.smith » November 20th, 2015, 5:45 am

60% RH is not low. In fact, cigar humidors are kept at 70% RH which you are close to. I would recommend investing in a dehumidifier and see how that affects your 306.2 error.

Send me a PM with your email address and I will see if I can track down A18.

brian.d.smith
Keithley Applications
Keithley Applications
Posts: 389
Joined: June 10th, 2013, 6:00 am
Country: United States

Re: 2000 self test fail 306.2

Post by brian.d.smith » November 20th, 2015, 6:00 am

There appears to be no A18. Here is what is in the repository for Axx

A02, A04, A13, A19, A20

Macduff
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Country: United Kingdom

Re: 2000 self test fail 306.2

Post by Macduff » December 2nd, 2015, 5:49 am

Thanks Brian, I can confirm firmware A19 works ok. I tried A20 and got an error that DC calibration was lost (and indeed it was). Switching back to A19 and thankfully the calibration was ok.

However, I am still getting 306 fails even after cleaning with IPA (and operating at 20-23 deg C, 45-50% humidity).

What I have found is when cold I get error 306.4 after a little while the 306 errors clear but when warmed up they persist with error 306.2.

Can you get hold of the full description of the 306 bank of errors for me? like you did with 306.2. There are 1,3 and 4 left.

Thanks

RogerioHein
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Joined: June 15th, 2017, 1:39 pm
Country: Brazil

Re: 2000 self test fail 306.2

Post by RogerioHein » June 15th, 2017, 3:31 pm

I have two K2000 with sequential serial numbers and running under A20 firmware in the same room. One of them is presenting the 306.2 error after about 30 to 90 minutes of operation. Room humidity is ranging from 60 to 67% today, at about 18 to 21 Celsius degrees​. Both are perfectly clean inside, both presenting same spot on results for DC voltage and ohm scales, always​ precise. What is happening, please? What is associated to this error code? Which kind of problems could result from this error? Many thanks in advance.

Macduff
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Joined: July 10th, 2015, 4:07 am
Country: United Kingdom

Re: 2000 self test fail 306.2

Post by Macduff » August 12th, 2017, 4:32 pm

RogerioHein, I would suggest going back to an old firmware (I'm assuming your meters are older but you have upgraded to A20). The A20 thing may be an issue because the calibration procedure and their constants in the EEPROM are different.

From what I can tell the older meters never had the 306 tests.

brian.d.smith was an excellent representative and has leaked a small amount of what 306.2 means, but once Tek and the corporates have taken over Keithley the thing has just become a brand and if anything goes wrong chuck it in landfill.

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