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 unit
3. Secret menu available now in MENU/GENERAL/SECRET
INIT-OPTS --> 5156
There 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.