Help to identify missing components on Agilent N9912A FieldFox main board - Page 1
Forum section: electronics / testgear

author: analogRF
author_rank: Super Contributor
timestamp: January 29, 2023, 02:32:14 pm
content: HiI got an N9912A which is a very early model (I think 2008). It could not boot because the front panel board was dead which I replaced with a board that I had bought (aimlessly) for parts long time ago for $40 even though I never thought I would need it one daySo anyways, the unit boots now with no errors and measures (both SA and VNA) and works fine except that RF board serial and part number/identity and SB serial and part numebr (whatever that means) show up as "?" in the system info page.I noticed that two components (U7 and U6) on the main board have been removed - see attached photo.I am surprised that the unit does not complain...but I guess they must have something to do with the problem I just describedI have not tested the LAN and SD card but USB port works. So maybe those are not working either...I cannot find any photo of this main board anywhere to figure out what those components must be. I am sure they are either some kind of voltage regulator or maybe a logic gate.I was wondering if anyone has a similar main board or pictures of it that can help me to identify the two missing parts

author: analogRF
author_rank: Super Contributor
timestamp: January 29, 2023, 07:27:36 pm
content: apparently SB means System Board which is the main board minus the CPU/flash module sitting on top of it.so the unit does not recognize the SN/HW Id/PN of the RF module and System Board while both of them work fineas far as I can tell. There are no errors and RF measurements are okit has something to do with those two missing chips I am sure. If someone can post a picture of this board it is highly appreciated.It's a very early unit. The System board PN is N9912-63004 while later models had N9923-xxxxx as their system board...I have seen pictures of those and they look completely different at least in this section of the board

author: TheSteve
author_rank: Unknown
timestamp: January 30, 2023, 03:07:26 am
content: The primary storage for the model and serial are in the MSP430 on the SB board(in encrypted form). The part # of the RF board will be stored in a small eeprom on the RF board.I'm guessing your SB board has a mini SD card slot - from before they switched to a regular sized SD card. I have a fox parts collection but none of them use the mini SD card.Your board is likely a proto/test board based on the number label on it. Have you tried updating the firmware on it - it could possibly be risky to do so.

author: analogRF
author_rank: Super Contributor
timestamp: January 30, 2023, 03:23:56 am
content: Quote from: TheSteve on January 30, 2023, 03:07:26 amyes it does have a mini-Sd card slot. I think later models have micro-sd. The S/N of the unit starts with US not MY so I assume it was made in the US.The FW is 2.xx and I wanted to update it but it must be updated to 4.xx first before updating to 8.0 however keysight have removed that old zip file for V4.0from their site so I could not update it.If someone has the 4.xx FW file I appreciate if you can share it.If the S/N and P/N and HW ID of the boards are stored in chips (on SB and RF) that are working, then why do they show up as "?" in the system info?My guess was that those two missing components perhaps provide power to a circuit that stores the board info but if it is stored in the 430 then I am wrong. Perhaps they have nothing to do with the S/N. I have not opened the RF board yet.

author: TheSteve
author_rank: Unknown
timestamp: January 30, 2023, 04:48:14 pm
content: Wow, version 2.x, I've never seen anything that old. Being it's a prototype those parts may have been removed to make it work. At one point I did have an archive of older firmware, not sure I still do. I'll have a look but again performing an update could be risky.Also, there is a command to set the model/serial. It may possibly work. It can only be run once if they aren't set.

author: analogRF
author_rank: Super Contributor
timestamp: January 30, 2023, 05:54:48 pm
content: Quote from: TheSteve on January 30, 2023, 04:48:14 pmhow do we know it's a prototype board? It does have a couple of bodge wires...it does seem odd that the unit works without those parts and does not complainalso it is odd if only the SN and PN of the boards depend on those two missing parts. But there is nothing else obvious so that's why I assumed they need to be there...yeah, I need FW 4.02 (not 4.03 because SN is USxxxx) if you can find it in your stuff, that would be awesomeI dont know the command to set the SN but the unit's SN and model are all ok, only the SB and RF boards show up as unknownand it is not just their SN. it is also their PN and Idendity (HW ID etc....)

author: TheSteve
author_rank: Unknown
timestamp: January 30, 2023, 06:11:51 pm
content: It is possible they were never programmed. You can read the eeprom on the boards and see what they contain. I believe the contents are in plain text. They are usually located not that far from the main interface connector.

author: TheSteve
author_rank: Unknown
timestamp: January 31, 2023, 04:06:15 am
content: Had and look and while I know I did have an archive of older firmware, I am not able to locate it now. I also don't know if I ever had anything that old.

author: analogRF
author_rank: Super Contributor
timestamp: January 31, 2023, 11:35:20 am
content: Quote from: TheSteve on January 31, 2023, 04:06:15 amThanks. I appreciate your help.I will try to locate and read the eeprom on the SB board and see if I can get anywhere. It must be on the other side of the boardbecause there is no eeprom on the top (visible) sideFor every board/module in the system there are a set of parameters (HW, ID, OF, OT, XT, NM) but they only show up as "?"for the SB and RF boards and yet these boards work fine. I wonder how that is possible?

author: TheSteve
author_rank: Unknown
timestamp: January 31, 2023, 04:50:55 pm
content: I believe it just assumes certain defaults and goes with it.