HP 53131A vs 53132A hardware differences - Page 1
Forum section: electronics / testgear

author: james_s
author_rank: Super Contributor
timestamp: March 25, 2020, 03:04:57 am
content: I noticed my 53131A actually has a 12 digit display and indeed it appears that the entire front panel board is the same as that used for the 53132A. I don't suppose it's possible to hack it to get those extra digits? The 53132A seems to use a whole different mainboard but I haven't been able to find out whether it's actually a whole different PCB or the same board with some of the missing components populated and different firmware. I assume somebody here must have compared the two? I was surprised I didn't see any discussion of this either here or elsewhere around the web. I don't really need the extra precision, I just quite like hacking gear to unlock latent capabilities.

author: TheSteve
author_rank: Unknown
timestamp: March 25, 2020, 03:09:06 am
content: It has been discussed here before(somewhere), just add the missing parts and update the firmware and you should be good to go. I don't think anyone has ever actually done it though.

author: eliocor
author_rank: Unknown
timestamp: March 25, 2020, 03:59:11 am
content: Several years ago I compared the two schematics: the '132A has some different values and some more ICs. It can be done except for one SMALL problem: the required ADC (AD7580JP) is UNOBTAINIUM* !The PCB are the same, just differently populated.*) if someone of you are able to find some AD7580JP, I would be grateful if you will sell me 1 or 2 pieces of them: all of the ones available on Chinese market are fake. Please do not ask me how I know! Maybe via some brokers, but....

author: coromonadalix
author_rank: Super Contributor
timestamp: March 25, 2020, 12:06:53 pm
content: reply #12 gives some infoshttps://www.eevblog.com/forum/testgear/my-ocxo-purchase/

author: CalMachine
author_rank: Frequent Contributor
timestamp: March 25, 2020, 04:42:51 pm
content: Quote from: james_s on March 25, 2020, 03:04:57 amI believe you can get those extra 2 digits with a longer gate time. If I recall correctly, a 10 second gate time yielded the full 12 digits

author: DeepLink
author_rank: Regular Contributor
timestamp: March 25, 2020, 06:33:45 pm
content: It is indeed possible to get hold of these ADC's, but they are expensinv ~25$ eachQuote from: eliocor on March 25, 2020, 03:59:11 am

author: eliocor
author_rank: Unknown
timestamp: March 25, 2020, 06:51:19 pm
content: QuoteNo, the higher resolution is due to a different HW (more precise ADC) with the same gate time.QuoteCan you recommend aTRUSTEDseller (1-2 quantity)? I got "burned" by fake ICs too much time!I have a 53131A which is waiting for the ADC transplant: the other components are already replaced/installed.

author: ch_scr
author_rank: Frequent Contributor
timestamp: March 25, 2020, 07:28:32 pm
content: via Octopart:https://www.rocelec.com/part/ANAANAAD7580JPZThey are an authorized seller: "Distributors marked (...) are members of the ECIA (Electronic Components Industry Association) or are authorized by the manufacturer to sell their products (or both)." HQ located in the US.

author: eliocor
author_rank: Unknown
timestamp: March 25, 2020, 08:22:18 pm
content: I asked for 1-2 pieces, not MINIMUM 9!

author: ch_scr
author_rank: Frequent Contributor
timestamp: March 25, 2020, 08:36:24 pm
content: Sorry, but i do not know another reputable source. OTOH: If you get it to work, the other 8 will sell on here for sure

author: SMB784
author_rank: Frequent Contributor
timestamp: March 25, 2020, 10:05:02 pm
content: Quote from: ch_scr on March 25, 2020, 08:36:24 pmUh, yeah! If someone has a definitive guide on how to upgrade the 53131 to the 53132 with all the necessary parts, I would definitely buy two from you.

author: CalMachine
author_rank: Frequent Contributor
timestamp: March 25, 2020, 10:30:47 pm
content: Quote from: eliocor on March 25, 2020, 06:51:19 pmI realize with the same gate time you would need the additional hardware. BUT, if you don't/can't get the additional hardware, I think increasing gate time will provide those extra digits. (Through averaging)If you don't have a 53131A and can't provide evidence that 53131A still yields 10 digits with gate time of 10 seconds.... then go away.

author: james_s
author_rank: Super Contributor
timestamp: March 26, 2020, 12:44:50 am
content: Shoot, thwarted by obsolete siliconWell a minimum order of 9 ADCs is not a huge deal if they are actually genuine, given what a 53132A costs I would bet there are easily enough people here who would go in for a couple even at $9 each if we could determine with some certainty what is needed. This is the sort of project that would be well suited to try on a scrapper motherboard that has something else wrong with it. I haven't looked at the datasheet for that ADC yet, is there something special about it or might there be an electrically compatible part in a different package that could be adapted?If I could get the other digits with a longer gate time that would be reasonable and at least it wouldn't bug me having those digits sitting there unused. I only got the counter recently and fixed it up, I've been using it for basic measurements but have not really delved into what all it can do yet. It's certainly a lot nicer to use than my old Protek counter, I was not even aware until recently that reciprocal counters were a thing. Had I know how much nicer these are I would have bought one years ago.

author: eliocor
author_rank: Unknown
timestamp: March 26, 2020, 02:12:24 am
content: Being stranded at home (I live in Italy) I was not able to reach my two 53131A units and my notes regarding the differences between the two models, so I made a quick "blink comparison" on the schematic pages.Attached you'll find the "blink" PDF (Red=53131A/Green=53132A) and an XLSX with the list of the different components.Hope it can be useful to someone of you....http://literature.cdn.keysight.com/litweb/pdf/5989-6307EN.pdfhttp://literature.cdn.keysight.com/litweb/pdf/5989-6308EN.pdf[Edited about one year later....]the spreadsheet has been replaced with an updated one (added C203), due to a suggestion by ytsejam: the older one has been removedhttps://docs.google.com/spreadsheets/d/e/2PACX-1vT2Cw7BYP3INiD25b4SDg2K0neCQuzmEF8RHb0b05xkjEJA0OHkFD3Vtjcn3vYeawHzW9UgewXsksDZ/pubhtml

author: ytsejam
author_rank: Contributor
timestamp: March 17, 2021, 06:35:55 pm
content: Quote from: eliocor on March 26, 2020, 02:12:24 amThanks eliocor! The overlapped schem comparison is amazing!I've successfully converted a 53131A to 53132A.

author: james_s
author_rank: Super Contributor
timestamp: March 17, 2021, 06:42:19 pm
content: That's cool, where did you get the parts to do so? I shelved the idea after determining that at least one of the critical parts was unobtanium.

author: ytsejam
author_rank: Contributor
timestamp: March 17, 2021, 06:58:47 pm
content: Quote from: james_s on March 17, 2021, 06:42:19 pmI got these ICs from China. Not from ebay, from Taobao instead. There're still some decent sellers who provide these NOS parts.

author: james_s
author_rank: Super Contributor
timestamp: March 17, 2021, 09:06:07 pm
content: Could you share a specific seller that had genuine parts? I might explore this project again.

author: eliocor
author_rank: Unknown
timestamp: March 18, 2021, 03:00:55 am
content: Thanks to ytsejam I corrected the spreadsheet with the differences between 53131A and 53132A models:you can find the new document attached to this message or you can consult it online:https://docs.google.com/spreadsheets/d/e/2PACX-1vT2Cw7BYP3INiD25b4SDg2K0neCQuzmEF8RHb0b05xkjEJA0OHkFD3Vtjcn3vYeawHzW9UgewXsksDZ/pubhtml

author: ytsejam
author_rank: Contributor
timestamp: March 18, 2021, 08:10:29 am
content: Quote from: james_s on March 17, 2021, 09:06:07 pmPM sent

author: anotherlin
author_rank: Frequent Contributor
timestamp: March 19, 2021, 09:07:20 am
content: Quote from: ytsejam on March 17, 2021, 06:35:55 pmWhere did you find the firmware ROMs?Also, do you know if firmwares can be upgraded for all mainboard revisions?According to the assembly level repair manual, there has been several ones.

author: eliocor
author_rank: Unknown
timestamp: March 20, 2021, 02:42:57 am
content: Quotego to KO4BB web site:http://www.ko4bb.com/getsimple/index.php?id=manualsand search for "53132A"BTW: I have updated the component list inserting DigiKey codes and links

author: TheSteve
author_rank: Unknown
timestamp: March 20, 2021, 02:47:58 am
content: There are also a couple threads posted on the forum here with firmware attached.

author: anotherlin
author_rank: Frequent Contributor
timestamp: March 20, 2021, 06:23:06 pm
content: Hi everyone,Thanks for your answers.I've also checked other 53132A related topics, lots of discussions and information.In particular, about how to switch to a less noisy fan or how to calibrate (there is even a calibration fixture in the work).It would benefit us all if we can put all the related information on one webpage, KO4BB comes closest to that.One more question, I've noticed that latest available firmware is "4613". That would be 2006 (HP serial number is 2 first digits + 1960).Will that work with any hardware revision of the 53132? In particular, early ones? Mine has serial number 3546A...Best regards,

author: ytsejam
author_rank: Contributor
timestamp: March 21, 2021, 05:39:08 am
content: Quote from: anotherlin on March 20, 2021, 06:23:06 pmYour serial number seems to be the early version with HP in stead of Agilent on the front panel.Based on a service note 53131-04A, S/N below 3710Axxxxx seems does not have the mother board 53131-60004.I think mother board will be the concern instead of firmware version.I also got an US version HP 53131A with S/N start with 3736A.It can be upgrade from FW rev3703 to rev3944 without any problem.Although I haven't tested yet, but I don't think it will be a problem for running rev4613.

author: SMB784
author_rank: Frequent Contributor
timestamp: March 21, 2021, 06:22:30 am
content: Well now I'm gonna have to look into this again! Thanks for all your great work everyone

author: daddioo
author_rank: Contributor
timestamp: May 29, 2023, 05:09:30 pm
content: Hello everyone, about a month ago I changed my two HP 53131A to 53132A, I followed all the comments on the site and downloaded the file for the components to add and replace, I did the job accurately with hot air welding, I replaced the eprom with the 4613 firmware, both frequency meters work fine SELFTST: PASS, GPIB AT 3, there is only one problem when I turn on this message UNCALIBRATED appears, I don't know what to do.I wonder if there is anyone who can help me.sorry for english, i'm using google translateThank you

author: HighVoltage
author_rank: Super Contributor
timestamp: May 29, 2023, 05:28:09 pm
content: Did you try to calibrate the instrument with an external 10 MHz signal?After a successful calibration with adjustment it should work and the message should stay away.

author: daddioo
author_rank: Contributor
timestamp: May 29, 2023, 05:50:38 pm
content: yes I did this calibration with 10Mhz from the gpsdo, but it is used to calibrate option 11 10Mhz high stability, nothing to do it always appears uncalibrated.

author: eliocor
author_rank: Unknown
timestamp: May 29, 2023, 06:04:04 pm
content: http://ftb.ko4bb.com/manuals/146.241.179.38/HP_53131A_53132A_53181A_Universal_Counter_Assembly_Level_Service_Guide.pdfhttp://file.yizimg.com/327204/201684-115911255.pdfsee chapter 2Leggiti il capitolo 2 per la calibrazione dello strumento

author: daddioo
author_rank: Contributor
timestamp: May 30, 2023, 03:52:32 pm
content: Calibration solved, luckily I had the function generator, I did step by step as the service manual said, I did the CAL: OFFS 1 and 2 (0V) then CAL: GAIN 1 and 2 (5V) and then CAL: TI QUIK ? 10Mhz square wave 1V peak peak, doing all this disappeared the writing UNCALIBRATED.Thanks everyone for your helpJoseph

author: alexvinassa
author_rank: Newbie
timestamp: June 28, 2023, 09:10:21 am
content: Hi ytsejam and Hi to everyone!looking at the photo attached to reply 14,It seems to me that you use two identical FPGA, the XC3142A 84-PLCC instead of one XC3142 (U58) and one XC3042 (U59). Does the circuit work correctly? Are the two fpga identical? Of course, with only one type of fpga is more practical. Thanks for your attention!

author: switchabl
author_rank: Frequent Contributor
timestamp: June 28, 2023, 04:49:40 pm
content: According to the datasheet (https://www.mouser.com/datasheet/2/903/3000-1595472.pdf), the XC3100A are pin- and bitstream compatible with the XC3000A but they can run significantly faster. So, yes, if you can't re-use the original U58 XC3042A for some reason, you could use two XC3142A instead.

author: alexvinassa
author_rank: Newbie
timestamp: June 28, 2023, 05:00:29 pm
content: yeah, I have come to the same conclusion as you! I will order all the components (aliexpressand mouser), I want to try this upgrade! I'm mainly driven by recklessness, but.. you have to have fun somehow!

author: nostril
author_rank: Newbie
timestamp: September 01, 2023, 11:38:01 pm
content: Hi all,Write me up as one of the successful 53131A to 53132A conversions.I have what's presumably a still-to-be-located scratchy solder joint causing intermittent MEAS and INTERP failures under cold conditions. But aside from this, I now have 12 digits per second if I let things warm up, or twist the board just right. Actually the fault is getting harder to reproduce the more I prod around (Murphy!!!)I seem to have fixed the intermittent issue by blasting under some chips with isopropyl+air, out came one or two very small solder balls. Perhaps they were just large enough to cause issues. But I can no longer reproduce the MEAS and INTERP failures except shorting two of the pins near where the ball came out (data line to gnd). I had one faulty joint (pin 29 on U59) but I couldn't reproduce the bug by lifting it to GND or VCC.I now have 12 digits per second on my "53131A".I would like to confirm a few things to add to the public knowledge around this hack since detailed internals of genuine '32s were hard for me to find to confirm some stuff before trying this hack:* I made all of the component replacements in the spreadsheet earlier in the thread.* All other passive components were sourced from Mouser using exact part number matching from the CLIP for maximum authenticity* I sourced the two ADCs from Aliexpress. Took a gamble here but I found someone had reviewed a listing from a seller as being non-fake.Probably someone recent from this thread* I used a 3142 and a 3042 FPGA per the 53132A CLIP, and not two of 3142. Again, sourcing-wise I took a roll of the dice here, but the same Aliexpress ADC seller had the 3142 FPGA in stock too.* I upgraded the SRAM to the 15ns IDT part number from the CLIP. I didn't bother trying with the original slower RAM as it may only have manifested as intermittent problems due to overclock. Not worth my time. This was obtained from an eBay seller with a fairly high (at least, high for a chip reseller) seller rating.* MC1403D reference was obtained from another eBay seller with a similar rating* I forgot to add it to my Mouser order, and I didn't yet want to burn the original EEPROMs even though I've backed them up... you never know... So I bought 4x AM29F010B from eBay as well. Ironically one of these ended up being the only non-working chip. Go figure. I can only speculate it is more likely to get counterfeits of popular chips that can be sold at volume?* I found there are two resistors missing from the delta/difference spreadsheet. This is a BOM change from 100R to 422R (R195 and R196). I'm not expert enough to determine if this makes any material difference.

author: ZGoode
author_rank: Frequent Contributor
timestamp: August 21, 2024, 05:40:33 pm
content: I'm looking to do this mod to my 53131A, but it appears to be one of the later revisions with the TSSOP flash instead of the PLCC flash. How do I upgrade the firmware? Do I need to remove the chip from the board to do that?

author: bson
author_rank: Unknown
timestamp: August 21, 2024, 09:41:48 pm
content: Just as a note if you're in the U.S.: Rochester Electronics sells the PLCC-28 AD7580JP in single qty for $30.28, is an authorized reseller and claims 1511 in stock.https://www.rocelec.com/part/01t4w00000POeYHAA1-AD7580JPThey're listed on AD's site as (under NY even though they're in MA?):Rochester Electronics, LLC16 Malcolm Hoyt DriveNewburyport,MA 01950United States1.727.873.0962 sales@rocelec.com

author: ZGoode
author_rank: Frequent Contributor
timestamp: August 22, 2024, 12:48:55 am
content: Quote from: bson on August 21, 2024, 09:41:48 pmRochester Electronics is a trustworthy source. Unfortunately they do not do small quantity orders. I was looking at buying from them, but they will not process orders under $250

author: bson
author_rank: Unknown
timestamp: August 22, 2024, 06:42:43 pm
content: Quote from: ZGoode on August 22, 2024, 12:48:55 amOh, I see - so that's why 9 would need to be ordered, to get over $250. I understand.I looked around and unfortunately don't see anything else of interest in the parts catalog. It's all old legacy stuff... I wonder what their business is, the repair parts business can't be large enough to pay rent for their sizeable building. (With a sign saying "Worldwide Headquarters" at the driveway!)

author: EEVblog
author_rank: Unknown
timestamp: July 10, 2025, 01:36:41 am
content: BUMP because I just did a video mentioning the update rate difference in the models.It would be cool to upgrade my 53131A to a 53132A

author: TheSteve
author_rank: Unknown
timestamp: July 10, 2025, 05:45:51 am
content: Quote from: EEVblog on July 10, 2025, 01:36:41 amMaybe you could do a video series on the upgrade - #1 figuring out what you need, #2 locating and ordering parts, #3 installing the parts and firing it up!

author: Mrt12
author_rank: Regular Contributor
timestamp: September 28, 2025, 06:22:19 pm
content: Good day dear colleaguesI notice some people here were successful in upgrading / modding a 53131A to a 53132A.Since few days, I am also now proud owner of a 53131A, without any options. But it's okay as I will use it anyways with an external reference, so I don't care about the internal crappy timebase.I wonder. In the attachment is the mainboard of my counter. Can I upgrade this to a 53132A, too? I am worrying a bit about the ADCs needed to do this, and the firmware ICs. Does anyone have spares and would sell some?

author: KungFuJosh
author_rank: Super Contributor
timestamp: September 28, 2025, 06:29:30 pm
content: You can get ICs to replace/upgrade the firmware. I posted about it here:https://www.eevblog.com/forum/testgear/hpak-frequency-counters-53132a-53131a-53181a/msg6009827/#msg6009827

author: Mrt12
author_rank: Regular Contributor
timestamp: October 01, 2025, 07:52:49 am
content: This is indeed very interesting!I notice from the components list, that there is also a change in the FPGAs.In the Excel list, I see that on the 53131A, the U58 FPGA is a XC3042 a. However, on the 53132A, the U58 is XC3142, and U59 is XC3042. So two different FPGAs according to the Excel list?But however, in this post herehttps://www.eevblog.com/forum/testgear/hp-53131a-vs-53132a-hardware-differences/msg3516678/#msg3516678we see that there are two identical XC3142 FPGAs. I wonder which is correct. Did you remove one of the FPGAs and replace it, or did you just add the missing FPGA?