Need Agilent 53131A and 53132A Calibration security code unlock method - Page 1
Forum section: electronics / general

author: SCSKITS
author_rank: Regular Contributor
timestamp: July 29, 2024, 10:03:51 pm
content: I need to "unlock" calibration on an Agilent 53131A and 53132A frequency counter. There is a security code in the units and it is not the factory default.Does anyone here have the secret recipe to unlock the units. If so, please contact me off list.Thank youed

author: pqass
author_rank: Super Contributor
timestamp: July 30, 2024, 12:22:23 am
content: This might help(bottom of page).

author: SCSKITS
author_rank: Regular Contributor
timestamp: August 07, 2024, 03:29:01 pm
content: That workedThanksed

author: OP-SEC
author_rank: Contributor
timestamp: February 15, 2025, 08:20:39 pm
content: Does ANYONE have the HP procedure to just wipe the code? I've tried everything. Keysight claims that they don't have the procedure anymore. (Lost tribal knowledge?)I bought a 53131A at auction and of course, it came with CAL SECURE enabled and it is NOT the default code or anything else I've tried. I have everything I need to completely re-calibrate the device after wiping it. I just can't find the procedure to actually wipe it.

author: pqass
author_rank: Super Contributor
timestamp: February 15, 2025, 09:11:04 pm
content: Did you try the link in reply #1?

author: OP-SEC
author_rank: Contributor
timestamp: February 18, 2025, 07:14:57 am
content: Indeed I did. I'm looking for advice on how to actually CLEAR the NVRAM since none of the variations of the default passcode work. It can't be possible that nobody has this information although, surprisingly Keysight claims that they no longer have the documentation on how to do this. These are great counters - especially for the price. Upgrading the timebase and adding the prescaler is as simple as can be but, I need to be able to calibrate the device after the fact.

author: chekhov
author_rank: Regular Contributor
timestamp: February 18, 2025, 09:17:41 am
content: Maybe it makes sense to read device's flash that stores calibration (and likely a password) and just find it ?Also, have you tried to unsecure via GPIB or via front panel ?On different instrument so far I failed to unsecure via GPIB but worked fine via front panel.

author: OP-SEC
author_rank: Contributor
timestamp: February 18, 2025, 09:30:10 am
content: I don't have the tooling or experience to read the flash. I also don't have a GBIB interface. Therein lies the rub.

author: pqass
author_rank: Super Contributor
timestamp: February 18, 2025, 06:27:52 pm
content: If you're looking for a quick&cheap GPIB interface, all you need is an Arduino UNO (or Nano), a connector, andthis software(discussionhere, manualhere).

author: OP-SEC
author_rank: Contributor
timestamp: March 10, 2025, 05:29:11 pm
content: Well, I ultimately returned the 53131A to the seller. They had no objections. I did the kindness of getting the onboard (stock) 10MHz reference calibrated to 10,000,000.000.004 Hz. The counter had been plugged in and powered up for several weeks when I did the calibration and it remained stable for the several days after I calibrated it prior to packing it up and shipping it back to the seller. So, for someone who is good with that, or who will only be using an external 10MHz reference, or someone who doesn't want to add the 3rd channel, it will make a great counter. It was in otherwise pristine condition. Alas, we can't win them all!