Keithley 5156 EEPROM / 6517x calibration - Page 1
Forum section: electronics / testgear

author: ksilabs
author_rank: Regular Contributor
timestamp: August 16, 2021, 05:33:15 am
content: Does anybody have Keithley Model 5156 Electrometer Calibration Standard?It is not very complex thing -- just 4 resistors and 2 capacitors in a box. I made a copy of it and I do have instruments to measure those 6 parts with more than adequate precision (Keysight B2987A Electrometer and Quadtech 1693 LCR Meter, both in calibration) but there is one unknown there -- it has a small EEPROM that tells what the actual values are.I have two Keithley 6517A instruments that I need to calibrate. 6517A allows programming actual values into that EEPROM so it looks like an easy thing. However, the problem is it MUST recognize that 5156 is connected to it before it can program anything. The only way it can do it is by checking that EEPROM for some magic string/byte/sequence. My EEPROM is empty so it won't find that magic and tells the fixture (or "Option" -- don't remember) is not connected so it won't talk to that EEPROM.Does anybody have that 5156 or knows what should be in that EEPROM for 6517x to recognize it as connected so I would be able to program it with my data?

author: picburner
author_rank: Frequent Contributor
timestamp: August 16, 2021, 06:48:24 pm
content: Have you seenthisTiN article?You have to go down to where he speaks of the K6517.From what I understand there is a secret menu that, once activated, among other things allows you to initialize the eeprom so that it is seen by the instrument.Then you will need to add the calibration values of the internal components.

author: ksilabs
author_rank: Regular Contributor
timestamp: August 16, 2021, 07:18:13 pm
content: Thanks, will try it later tonight when I'm back at my workbench.

author: ksilabs
author_rank: Regular Contributor
timestamp: August 16, 2021, 09:16:20 pm
content: OK, no bananas6517A, firmware C05, power on with SEQ and Power Source UP, no secret menu

author: ksilabs
author_rank: Regular Contributor
timestamp: August 16, 2021, 10:14:58 pm
content: OK, it is Power Source Down, not Up.It does set 5156 as connected but INIT does nothing, returns immediately and no changes in the EEPROM.It might be that I didn't connect it properly as connector pinout is kinda misleading (which side it is?). Re-checking it now.

author: ksilabs
author_rank: Regular Contributor
timestamp: August 16, 2021, 11:35:23 pm
content: Won't work with any of relatively modern EEPROMs. 5156 shows X24C01 EEPROM and it looks like it is NOT replaceable even with X24C01A.X24C01 is quite interesting (OLD?) EEPROM -- it is NOT addressable according to its datasheet. That means it does NOT have I2C Slave Address and assumes it is always addressed and Master talks to it exclusively. It doesn't expect Slave Address so regular EEPROM is never addressed and never responds.Have to find that old weirdo, X24C01 WITHOUT "A" and it must be Xicor...

author: picburner
author_rank: Frequent Contributor
timestamp: August 17, 2021, 05:23:21 am
content: As you have already discovered the eeprom x24c01 and x24c01A are not interchangeable, probably the brand is not so important but the final "A" is!QuoteThe author probably wrote the article afterwards and confused up with down, however you can't find the keystrokes to access the secret menu in any Keithley manual.

author: ksilabs
author_rank: Regular Contributor
timestamp: August 17, 2021, 05:41:36 am
content: Quote from: picburner on August 17, 2021, 05:23:21 amYep, luckily it was that simple, just DOWN instead of UP, not some other key.Waiting for NOS Xicor 24C01 parts to arrive...

author: ksilabs
author_rank: Regular Contributor
timestamp: August 22, 2021, 10:30:50 pm
content: Quote from: ksilabs on August 17, 2021, 05:41:36 amOK, it worked like a charm with ORIGINAL Xicor X24C01S, no problems. Recognized as 5156 on regular power-up, calibration menu shows nominal values (haven't changed those to real values yet) as it is supposed to.

author: picburner
author_rank: Frequent Contributor
timestamp: August 23, 2021, 04:43:52 am
content: Well, the positive result of this test and the description of the correct procedure could also help others in the same situation in the future because the k6517 is not such a rare instrument in this forum.

author: little.tesla
author_rank: Regular Contributor
timestamp: May 22, 2024, 04:05:59 pm
content: Hi,I want to confirm a successful replication of the programming 5156 EEPROM and a few hints for others who want to replicate it as well.It only works with an ORIGINAL Xicor X24C01S, because the instrument expects an non addressable EEPROM (e.g. all newer EEPROMs won't work)The connection of the EEPROM is as shown in the Keithley service manual (I added a 100nF to the supply). The connector pinout shown works fine as well and it's as viewed on the 5156.As a connector I did use a pigtail KMDPLX-8S-280 from Kycon, whereby the 280 represents the wire length (e.g. from Mouser). The enclosure is just one I had on hand. For the connection to my 6517A I bought a non original cable local (ACT AK5849).To initialize the EEPROM perform following steps as per xDevs description:1. Ensure unit is powered off.2. Press and hold button "SEQ" and button "Voltage source DOWN" and power on unit3. Secret menu available now in MENU/GENERAL/SECRETINIT-OPTS --> 5156There is NO feedback if the action was successful (or not). To be sure I did read out the content of the EEPROM. I've attached a copy for reference.To keep the calibrator box more general and to avoid complications with RFI etc. I kept the EEPROM external. Next challenge is going to be the characterization of the resistors.