Agilent 34970A, Battery replacement and repair - Page 1
Forum section: electronics / repair

author: HighVoltage
author_rank: Super Contributor
timestamp: December 11, 2015, 05:39:28 pm
content: This Agilent 34970A Data Acquisition unit I bought used in broken condition very cheap.After opening it up, I found the problem right away with a loose ribbon cable.Then I took it completely apart and cleaned it all and replaced a ribbon cable.It seems to work perfect now.But I measured the battery and it has only 2.6V instead of 3VSo, I would think it needs to be replaced.Does anyone here have experience with replacing this battery?Do I need to keep the unit powered up or at least plugged in, during the exchange of the battery.Anything else to watch out for?Here are some pictures:

author: nfmax
author_rank: Super Contributor
timestamp: December 11, 2015, 05:51:04 pm
content: Yes, I have replaced the battery in the unit I bought second-hand a few weeks ago. You should disconnect the unit from the mains supply, calibration data (including relay operation cycle counts) is not dependent on the battery. The procedure is described in the service manual and it's pretty straightforward.My unit had a cylindrical, through-hole tag mounted battery, not a surface mount button cell like yours. I think these have a larger capacity: if you look at the PCB you will see there are three holes for the battery tags so presumably you can use either. Be careful to choose a battery with the correct pin spacing at the 2-pin end, and with the correct polarity - all possible variants are made and only 1 of the 4 is right!It sounds as though your battery, while dying, is not quite dead yet. When it finally dies, you will get an error indication each time you power up the unit & 2 codes - clock lost & memory lost. But no harm in replacing the battery now while you are working on it anyway!

author: magnehh
author_rank: Contributor
timestamp: December 11, 2015, 10:02:17 pm
content: I believe the HP 34790A's had the "long" cell and the old, horrid FRAM. While in the Agilent version, they changed both of them.I do have two multimeter modules for these if you're interested. Only problem is, they loose the cal data when you unplug them from the main board. :-P

author: HighVoltage
author_rank: Super Contributor
timestamp: December 12, 2015, 12:02:45 pm
content: Thank you both for the feedback.Now I just have to find the right battery with the solder tabs at the right spot.The original Panasonic number isBR2477AThat one seems not to be available.

author: PA0PBZ
author_rank: Super Contributor
timestamp: December 12, 2015, 12:26:04 pm
content: http://www.digikey.com/product-detail/en/BR-2477A%2FVAN/P030-ND/273650

author: HighVoltage
author_rank: Super Contributor
timestamp: December 12, 2015, 12:58:43 pm
content: Thank you for the link, PA0PBZ

author: nfmax
author_rank: Super Contributor
timestamp: December 12, 2015, 01:21:19 pm
content: Quote from: HighVoltage on December 12, 2015, 12:02:45 pmThe battery I fitted was a Varta, Farnell part number 197-2505. This has two pins at the positive end, spaced at 7.5mm. The dead battery was reading about 0.65V (!), and I was seeing error codes 202 and 204 at each power on. I don't think this was the original battery though as there was uncleaned flux on the PCB. My unit is an Agilent labelled one, as are the plug in modules.I have a spare copy of the (English) service guide - PM me if you are interestedMax

author: HighVoltage
author_rank: Super Contributor
timestamp: December 12, 2015, 02:02:48 pm
content: PM sent,I ordered the original battery from Digikey and I will post again, once the replacement battery is installed.May be a full calibration will be required afterwards.

author: Jwalling
author_rank: Unknown
timestamp: December 13, 2015, 12:10:51 pm
content: Quote from: HighVoltage on December 12, 2015, 02:02:48 pmFYI: I've found that these units will accept a standard horizontally mounted CR2032 battery holder like you would see in any PC motherboard. Sure the battery doesn't last as long, but when you need to replace it, it's a snap.Jay

author: HighVoltage
author_rank: Super Contributor
timestamp: December 13, 2015, 12:33:35 pm
content: Quote from: Jwalling on December 13, 2015, 12:10:51 pmThank you for this information, great idea!I will get a CR2032 holder and take a closer look.

author: Jwalling
author_rank: Unknown
timestamp: December 13, 2015, 01:35:09 pm
content: Quote from: HighVoltage on December 13, 2015, 12:33:35 pmYou're welcome. Note that the pins of the holder don't go in the same holes as the original battery, they go in the larger holes between the original pin holes. You'll figure it out using a DMM on continuity - just watch out for polarity. You'll also need to scrape away a bit of the solder mask before soldering it in. I use a bit of scotch tape to hold in the battery holder since you have to solder it in upside down.Jay

author: dom0
author_rank: Super Contributor
timestamp: December 13, 2015, 02:55:44 pm
content: Quote from: nfmax on December 11, 2015, 05:51:04 pmThe battery powers only the RTC?In my olde 3478A there was one of these large (thicker but shorter than a AA mignon) lithium cells, over 30 years old, still had 2.95 V or so on it :-)

author: nfmax
author_rank: Super Contributor
timestamp: December 14, 2015, 11:14:15 am
content: Quote from: dom0 on December 13, 2015, 02:55:44 pmThe battery also supplies the SRAM used to hold the measured data - this is really useful as you can take measurements on an experiment in the lab, then bring the datalogger back to your desk to download & analyse the data. The one I bought recently was for home use, but we have used dozens of these dataloggers at work since I bought us the first one back in 1999!

author: HighVoltage
author_rank: Super Contributor
timestamp: December 23, 2015, 09:12:46 pm
content: Today I installed the new battery (original replacement from Digikey)The Battery was out for about 6 minutes and the instrument kept all calibration data.Tomorrow I will check the calibration on all ranges.It seems so far, that it was a success.Thanks for all your help.

author: plesa
author_rank: Frequent Contributor
timestamp: December 31, 2015, 05:51:57 pm
content: I know that it is little bit late, but in my unit fir battery CR14250, it is rotated by 90 degree compare to your picture.

author: HighVoltage
author_rank: Super Contributor
timestamp: December 31, 2015, 05:54:44 pm
content: Quote from: plesa on December 31, 2015, 05:51:57 pmHow can it be rotated 90 degree?You mean 180 degree?Can you take a picture of what you have in your unit?Thanks

author: HighVoltage
author_rank: Super Contributor
timestamp: December 31, 2015, 05:59:11 pm
content: BTW, this 34970A has been turned on for a while now and seems to be very stable.I still need to do a detailed calibration check.Do you usually check the calibration on all channels of a 901 card to also include the multiplexer card ?

author: plesa
author_rank: Frequent Contributor
timestamp: January 01, 2016, 01:03:57 pm
content: I calibrate only one channel, but before I highly suggest to check the relay card resistance and relay odometer.Quite funny is the fan placement on side completely covered with enclosure, I'm quite curious what is purpose of this fan, because on another side it is covered by IEC connector assembly.So It cannot cannot help to flow air inside instrument, like we saw inside Keithley 7510.

author: plesa
author_rank: Frequent Contributor
timestamp: January 03, 2016, 12:59:16 pm
content: What I forgot to mentioned - check the relay counter on internal DMM (if present).I do not find the way how to check it through front panel, only remotely by DIAG:DMM:CYCLES?For instance on my unit the DMM relay K102 is almost dead >10M cycles. Probably someone selected different ranges 10V/100V or similar switching problemFor details check "Chapter 5 Theory of Operation - Internal DMM" in service manual.I needs to desolder relay and replace it by new one Omron G6SU-2-DC3Because my unit has only one issue ( errors in self test 740/741/748 and etc) all were due to unlocked instrument, when I locked calibration all are gone.Battery has 3V.Based on the relay counter I expect that unit failed calibration due to K102 relay.There is another trap - if you checking basic performance of modules put into terminal some wire. Unit has been supplied with two modules. Both as faulty ones with marking which relay is faulty.So I checked the odometer and maximum was 25 cycles.DIAG:RELAY:CYCLES? (@101,102, ....)So I checked them according to service manual and yes they seems to be not working.So I expect that someone reset relay counter, but modules were almost new. When I measured the relay contacts all were OK, yes the problem was in terminals!!!!!The guy which has been cheeking the modules make same mistake probably.If you are measuring the screw, there is ope circuit, when you put there some wire it is OK

author: HighVoltage
author_rank: Super Contributor
timestamp: January 03, 2016, 01:15:50 pm
content: Thank you plesa, this was really good information.One more question,If you would replace a relay, can you reset the counter to reflect the new relay installation?

author: plesa
author_rank: Frequent Contributor
timestamp: January 03, 2016, 01:30:31 pm
content: Yes, both can be cleared/reset. You needs to unsecure the instrumentCAL:SECURE:STATE OFF,HP034970and thenDIAG:DMM:CYCLES:CLEAR (1,2,3 ) depends on which relay counter you want to resetDIAG:RELAY:CYCLES:CLEAR (@101,102, ...) depends on which relay counter you want to resetThe good document for this is manual for 34972A instead of 34970A manualhttp://cp.literature.agilent.com/litweb/pdf/34972-90001.pdfor old HP manualhttp://www.keysight.com/upload/cmc_upload/All/34970-90003_users.pdfThat's pity that this is not possible for bench DMM, or I do not know how.This can be helpful to predict the relay failure like you have on 34410A.Which firmware you have and what is response to SYSTem:VERSion?In meantime I found only service note to my serial numberhttp://literature.cdn.keysight.com/litweb/pdf/34970A-13.pdfrelated to stability of 400k Vishay UXB thin film resistor which can affects 10M and 100M Ohms measurement.And another related to connection bwtween main board and DMMhttp://cp.literature.agilent.com/litweb/pdf/34970A-14C.pdfFunny is that my serial number is not affected by cover exchange, but in real it does not have proper cover ( so check if your cover has ventholes on righ side and bottom end).Complete list you can found here:http://servicenotes.literature.keysight.com/litapp/SearchSN.do?method=openExternalSNSearch&prodNum=34970AAlso interesting document about change FRAM ( when you have 740 errors ) in attachment.

author: plesa
author_rank: Frequent Contributor
timestamp: January 03, 2016, 10:54:59 pm
content: I just found that latest firmware is v13, programmed in U401 ( 27C4096 OTP EPROM). I will really appreciate if someone can post version v12 or v13 for upgrade.

author: HighVoltage
author_rank: Super Contributor
timestamp: January 04, 2016, 02:05:30 pm
content: I have two of these Agilent 34970A units.How do I test what FW version is installed?Can I do it over the UI?

author: plesa
author_rank: Frequent Contributor
timestamp: January 04, 2016, 05:50:35 pm
content: Quote from: HighVoltage on January 04, 2016, 02:05:30 pmVersion of FW is in response to *IDN? command, it is first number ( XX-X-X).Do you have PLCC 44 package programmer?

author: nfmax
author_rank: Super Contributor
timestamp: January 05, 2016, 02:40:30 pm
content: Quote from: plesa on January 04, 2016, 05:50:35 pmKeysight Connection Expert also shows the firmware version from the ident string. My unit returns 12-1-2. Does anyone know what the differences are?Max

author: Jwalling
author_rank: Unknown
timestamp: January 05, 2016, 02:49:05 pm
content: Quote from: nfmax on January 05, 2016, 02:40:30 pmTake a look at service notes - there's a lot of info on the firmware (and other) changes:http://servicenotes.literature.keysight.com/litapp/SearchSN.do?method=openExternalSNSearch&prodNum=34970AWould be nice if you could download and burn your own PROM.Jay

author: plesa
author_rank: Frequent Contributor
timestamp: January 05, 2016, 03:21:56 pm
content: Found following thread about FRAM exchangehttps://www.eevblog.com/forum/testgear/agilent-34970a-errors-and-battery-replacement/And buch of others with usefult information for 34970A restorationhttps://www.eevblog.com/forum/testgear/hp-34970a-error-741-fix/https://www.eevblog.com/forum/testgear/hpagilent-34970a-teardown/https://www.eevblog.com/forum/testgear/hp-34970a-errors-740-741-747-748/Thanks Free_ElectronSo ordered two pieces of Cypress FM24C04B-G and hopefully I will replace also 27C4096 OTP EPROM with firmware and K102 relay.Latest still seems to be v13.

author: plesa
author_rank: Frequent Contributor
timestamp: February 13, 2016, 09:09:03 am
content: Scored on 34901A ( 20 Channel Multiplexer (2/4-wire) Module) this is the most universal module for 34970A.Started with check according to service manual and found that five relays does not work (K107-K111).According to odometer all relays has about 500k cycles, which is minimal relay life ( electrical ).Contact resistance on relays is according to spec in manual ( < 2Ohm).In the service manual for 34970A is schematic for modulehttp://cp.literature.agilent.com/litweb/pdf/34970-90012.pdfon page 245.Suspected IC was immediately 74HC574 ( U104 and U103) and U104 it is dead according to IC tester. Logo on IC is Phillips, manufactured in 2003, so Agilent needs to have plenty of them, module has been manufactured in 2010 ( firmware 2.3 )uC soldered directly to board without socket. Another strange things is that the 20 channels relays are made by Panasonic TX2 and not by Omron G6SU like on previous version of module.

author: douardda
author_rank: Regular Contributor
timestamp: June 02, 2016, 07:46:53 pm
content: Hi,I just bought a sick 34970A (with a 901 and a 907 for 200€ with shipment).It has a sick display (at least one of the 2 flv drivers is dead, and the display itself is a quite dim). I'm waiting for the replacement parts, meanwhile I'm playing with it via the GPIB interface (I'm trying to implement a sigrok driver for it).And it gives enough 700 errors (including several DMM cal data lost) each time I power it up that I can tell its 2 FRAMs are dead.It also have a very old firmware revision (8-1-2), so since I am in the process of trying to give it a chance for a second life, I'd like to upgrade its firmware.Has anyone dumped a recent firmware? plesa have you found a v13 dump somewhere?Thanks,David

author: HighVoltage
author_rank: Super Contributor
timestamp: June 02, 2016, 07:50:10 pm
content: Keep us updates with your repair and show some pictures.I have an older version and a newer version.May be I can get the FW versions and read them out for you.

author: douardda
author_rank: Regular Contributor
timestamp: June 18, 2016, 12:20:10 am
content: Hiso my attempt of repairing my 34970A is not going so well so far.I've replaced the 2 VFD drivers (putting them in PLCC sockets instead of soldering them directly).But the VFD is not reacting well to my rejuvenation assaults.With the VFD being dead, I was thinking about hacking the device by replacing the VFD display with a blue OLED display managed by an arduino or a nucleo that would take place of the 2 shift registers (in the VFD drivers) to decode what to display.But I'm afraid I killed (don't know exactly how, I did nothing specially wrong when it started to fail) the U1 microcontroller of the display board yesterday evening since it does not give me any more signal on SEGDATA (U1 pin 5).From there, I see 2 options:- I find a replacement front-panel unit (they seem to be still available from Keysight for a bit more than 200€)- I inspect the serial communication to rewrite a implement a new front-panel management controller.I've looked a bit at what happens there, and it should not be too difficult.I don't event want to try to dump the ROM from U1, since being a 87C51, it's most probably "encrypted"(XORed with a 32bit key). And on my unit, if P1.3 pin is dead, I guess I won't be able to dump theROM (unless it still work as an input, sice P1 is used to set the address when dumping the ROM). I may give a try. I don't know yet.The good news is that I've changed the FRAM chips (both on the main board and the DMM)and it does not complain any more about these.Quote from: HighVoltage on June 02, 2016, 07:50:10 pmThat would be awesome! Yes please!PS: I've written a blog post on this work on my modest blog (https://whatever.sdfa3.org).

author: douardda
author_rank: Regular Contributor
timestamp: June 21, 2016, 10:40:20 am
content: For the record, I've asked keysight if they would accept to make the ROM content of the display panel microcontroller available, but they are reluctant to respond favorably to my request:QuoteI don't really understand why they can't make these kind of "firmware" available (besides the time required to find the correct file andupload it on the support web site). Any Keysight guy is hanging around? ;-)So now I guess I'm good for a reverse ingeeniring of the serial protocol between the 2 boards...David

author: HighVoltage
author_rank: Super Contributor
timestamp: June 21, 2016, 11:22:09 am
content: This usually is the problems with larger companies.As you know, I have a 34970A around and could do a readout for you.But I am not sure if it is the same version.

author: douardda
author_rank: Regular Contributor
timestamp: June 21, 2016, 12:24:48 pm
content: Quote from: HighVoltage on June 21, 2016, 11:22:09 amyup, I did not expect too much, so I was not disappointed :-)Quote from: HighVoltage on June 21, 2016, 11:22:09 amYes, please! that would be very nice. I'm looking for both ROMs in fact: the display panel's 80c51one (if it's not encrypted), and a reasonably recent version of main CPU one.David

author: julian1
author_rank: Frequent Contributor
timestamp: June 25, 2016, 06:22:44 am
content: Could someone tell me if it's normal behavior for the 34970a to perform a full startup when power is applied to the unit (eg. by plugging in the power cord).Or does it need the soft-start button on the front panel to be pressed.

author: Jwalling
author_rank: Unknown
timestamp: June 25, 2016, 09:29:24 am
content: Quote from: julian1 on June 25, 2016, 06:22:44 amI've never seen one do that. Maybe there is a persistent setting that enables this? If you want to stop it from doing the full test, there's probably a way to reset the unit to factory defaults.Jay

author: julian1
author_rank: Frequent Contributor
timestamp: June 26, 2016, 06:08:55 am
content: Quote from: Jwalling on June 25, 2016, 09:29:24 amThanks. It's wasn't doing a full-test, but plugging in the power cord, made it start up automatically. Without needing to also press the front-panel button.I suspect the power-management u104 chip may have been incorrectly issuing a reset due to sensed a voltage drop when power was first applied.

author: Jwalling
author_rank: Unknown
timestamp: June 26, 2016, 10:05:23 am
content: Quote from: julian1 on June 26, 2016, 06:08:55 amOK, I misunderstood what you were saying.They will do that when the battery is replaced. Maybe yours is getting low? They will also do that when AC power is removed then restored if it was powered on.Jay

author: julian1
author_rank: Frequent Contributor
timestamp: June 26, 2016, 10:54:14 am
content: Quote from: Jwalling on June 26, 2016, 10:05:23 amGood. thanks for clarifying.

author: douardda
author_rank: Regular Contributor
timestamp: June 29, 2016, 09:21:26 pm
content: Quote from: julian1 on June 25, 2016, 06:22:44 amActually, there is an option to configure this behavior in the "Utility" menu (Shift + Advanced).David

author: gamalot
author_rank: Super Contributor
timestamp: August 15, 2016, 12:08:56 pm
content: I have just upgraded my 34970A, using CR2302 (in holder) to replace the original CR14250 battery

author: carl_lab
author_rank: Frequent Contributor
timestamp: August 15, 2016, 07:03:40 pm
content: Which lifetime do you expect using your CR2032?Capacity of CR2032 (230mAh) is only 1/4 of CR14250SE (~900mAh)...http://www.varta-microbattery.com/applications/mb_data/documents/data_sheets/DS6032.pdfhttp://www.batteryjunction.com/varta-cr12aa.html

author: Jwalling
author_rank: Unknown
timestamp: August 15, 2016, 07:22:43 pm
content: Quote from: carl_lab on August 15, 2016, 07:03:40 pmI did some measurements a few years ago, and one could expect at least a year or so.Then figure:1. Ease of repair - no de-soldering required and no stressing the same solder pads over and over. Just pop a new one in. If you're careful, you can do it without losing your setups and logging memory with power applied.2. Cost - about 30 cents (US) versus $5 or more.Jay

author: gamalot
author_rank: Super Contributor
timestamp: August 16, 2016, 04:58:47 am
content: Quote from: Jwalling on August 15, 2016, 07:22:43 pm

author: HighVoltage
author_rank: Super Contributor
timestamp: April 20, 2017, 01:19:28 pm
content: I was lucky to get a34972Avery cheap, because it was "broken" and I expected another repair.This is the successor of the 34970A with LXI and LAN and USB connection.Turns out to be that the display did not turn on, because it was turned OFFThe instrument works and looks like new, even the fan had no dust on it.This unit was built in 2012 and even the calibration certificate was online at the Keysight website.So, in other words, NO repair needed.Now I took the opportunity to look inside and take some pictures.This new model looks very different in the inside, compared to the older models.Mostly noticeable, a new battery holder at the bottom of the unit.

author: HighVoltage
author_rank: Super Contributor
timestamp: April 20, 2017, 01:24:29 pm
content: Pictures of the inside

author: HighVoltage
author_rank: Super Contributor
timestamp: April 20, 2017, 01:29:05 pm
content: More pictures of the bottom

author: nfmax
author_rank: Super Contributor
timestamp: April 20, 2017, 01:30:32 pm
content: Oh wow! I was only half serious when I suggested checking if the display was turned off, and that turned out to be the problem after all.I gather the 34970A is basically a 34401A type DMM + scanner, while the 34972A is a similar scanner but based on a later DVM - the 34410A, I think (never had either of these in my hands to look)

author: HighVoltage
author_rank: Super Contributor
timestamp: April 20, 2017, 01:35:15 pm
content: Quote from: nfmax on April 20, 2017, 01:30:32 pmYes, you were right with the display, that was the first I checked.That is an interesting suggestion you make there, that this 34972A model is based on the 34410A.I will have a closer look.It should be easy to find out, since the 34410A was much better in low voltage AC measurements, than the 34401AThat will be an interesting test.Interestingly, the bootup time takes a little longer than the older models.

author: HighVoltage
author_rank: Super Contributor
timestamp: April 20, 2017, 02:51:55 pm
content: Unfortunately this is not confirmed...It seems the 34972A is also using the circuitry of the 34401A, at least when it comes to low AC voltage measurements.It is a known fact that the 34401A has problems to accurately measure low AC voltagesHere I did a test with250 mV AC, 400 HzThis is the lowest setting of my calibrator.and these are the measurement results:- 34401A:54 uV, jumping around +/- 8 uV- 34410A:250.8 uV, stable- 34411A:253.7 uV, stable- 34970A:53.4 uVjumping around +/- 8 uV- 34972A:52.2 uVjumping around +/- 8 uV

author: nfmax
author_rank: Super Contributor
timestamp: April 20, 2017, 03:27:24 pm
content: Well that is interesting. I wonder why they did such a major redesign on the 34972A if they weren't updating the DMM? I've always preferred the 34401A over the later 6 1/2 digit DMMs because it doesn't have a fan, but there does seem to be a real performance gain

author: HighVoltage
author_rank: Super Contributor
timestamp: April 20, 2017, 03:41:43 pm
content: Quote from: nfmax on April 20, 2017, 03:27:24 pm- Removing the GPIB interface- Add LAN- Add USB- Add LXIAnd probably solving lots of problems with the older design like with the battery and FRAM.But I am surprised as well, of how much effort was put in to the re-design.QuoteYes, I agree.And even with some 34410A and 34461A meters around, I like to gram the 34401A for most of my daily measurements.May be just habit.The fan noise of the 34410A can be reduced with a lower fan speed / different fan.Back to the 34972AIt seems the screen update rate is also higher on the new model, compared to the old one.

author: nfmax
author_rank: Super Contributor
timestamp: April 20, 2017, 03:46:49 pm
content: Quote from: HighVoltage on April 20, 2017, 03:41:43 pmHeh! It took long enough to wean me off my 3478A onto a 34401A. Having the ranges running up to 3xxx means there is often no significant resolution gain on the 344401A - though the accuracy specification is better

author: HighVoltage
author_rank: Super Contributor
timestamp: April 20, 2017, 04:55:54 pm
content: Actually on the 34401A as well as the 34970A / 34972A you can gain one more digit and make it a 7 1/2 digit meter, if you read out the data remotely. It is just probably not very useful.