Changing battery in a HP 3478A - can i use a 3v Lithium ?

[bingo600]

Inspired by these nice pictures of a 3468a battery change
https://www.eevblog.com/forum/testgear/quick-question-about-hp-3468a/msg197337/#msg197337
http://mrmodemhead.com/blog/hp-3468a-battery-replacement/

I decided to check/change the battery in my HP 3478A
SN : 2911A66xxx - Means : (29+60 = 89) = 1989 , Week 11 , A(merica)

My serial is almost the same as Daves  , and i have the same yellow battery in.
https://www.eevblog.com/forum/blog/eevblog-427-hp-3478a-multimeter-teardown/msg194349/#msg194349

I just measured the battery to 3.4170v - with a Agilent 34401A , and Bravo said "watch out" here.
https://www.eevblog.com/forum/blog/eevblog-427-hp-3478a-multimeter-teardown/msg195033/#msg195033

I have been preparing a bit , and have gotten som Lithiums from the "net" , even 2 Taradians.
But they have the "reverse polarity" , meaning - on the dual pins and + on the single pin.

I also have a "perfect fit" but it's only a 3v Lithium , could i use that ?.

I have attached some pics , and "snipped" 3 pages from the service manual to give an idea of the buildup.
The Ramchip (U512) in pg. 154 , and the battery circuit with CR764 on pg. 156.

On the schematic they say 3.0v , so i hope i can use the 3v Lithium.

But will not if anyone says its really a bad idea.



Hope to get some advice now that i have the "lid off" and is all "warmed up".
I have prepared  a spare Taradrian with an 1n4148 on + , have a propane solder iron ready.

I'll leave the meter powered on mains and solder the spare taradrian across C510 , and then desolder the original battery , and solder the new one in.

Edit: I just found this with the same part£ as in HP's manual
http://www.ebay.com/itm/1420-0278-Agilent-HP-Lithium-Battery-3V-95A-for-3478A-/350546682442

It's a 3v Lithium , so i think i should be ok or ?


TIA
/Bingo

[bingo600]

Well being impatient ....
I performed the surgery , and the patient survived 

The new battery delivers 3.0587v across C510 , sorry i didn't measure what the old one delivered across there.

I took a pict of the old battery , and it's a Panasonic BR-2/3A 3v cell.

So that's the one , also in Daves reviewed meter.

Ohh this is the battery i used : SANYO / FDK CR17335SE - 2/3A "med loddeflig (1 stk.)" ... the "xxxx" means with solder tabs
http://www.batteribyen.dk/sanyo-fdk-cr17335se-23a-med-loddeflig-1-stk-3112

Specs
http://www.fdk.com/battery/lithium_e/pdf/data_sheet/hcc_type/CR17335SE_spec-sheet.pdf

If i read it correctly , it should be good for 10+ years (@23 C) , the curves shows 10y with a 20uA load , and the Ram DS says it uses 10uA

/Bingo

[ModemHead]

I've attached the datasheet I dug up for the uPD5101L SRAM chip.  It indicates that the minimum voltage needed for data retention is 2.0V (third page).  So the 3.0V battery should be OK, as you've already figured out...

[bingo600]

Thanx 

I did see that, before i changed my battery.

I performed the "surgery" with mains on , and also with a 3v6 taradian soldered to C510 , via an 1n4148.
C510 is the silver cap seen here , just above the ram chip  - on sIMG_0513.jpg
https://www.eevblog.com/forum/beginners/changing-battery-in-a-hp-3478a-can-i-use-a-3v-lithium/?action=dlattach;attach=41988

Note "-" on the cap is towards the frontpanel , and "+" is towards the rear , it makes sense as it's pin-22 that's vcc.
I suggest always confirming with a DMM before soldering wires on.

[bingo600]

Ohh...

Does the Agilent 34401A also have a battery for calibration data retention ?  (i'm lazy) ...
I'd really hate to loose my cal on that one.

/Bingo

[ConKbot]

Is that section of the board floating/not ground referenced? You wouldnt want to short the battery out with a grounded soldering iron tip.   Or is that why you used the propane soldering iron?

Even if it doesnt reset the memory, shorting out a lithium battery isnt exactly a good thing.

[bingo600]

Is that section of the board floating/not ground referenced? You wouldnt want to short the battery out with a grounded soldering iron tip.   Or is that why you used the propane soldering iron?

Even if it doesnt reset the memory, shorting out a lithium battery isnt exactly a good thing.

I used the Propane iron just for that reason.

/Bingo

[johnh]

I was just wondering if its possible to build an adaptor to read the contents of the memory. So you could back it up

[nukie]

No it doesn't. Don't worry bout it.

Ohh...

Does the Agilent 34401A also have a battery for calibration data retention ?  (i'm lazy) ...
I'd really hate to loose my cal on that one.

/Bingo

[nukie]

Hello Bingo what's the date code on your new battery?

[bingo600]

Hello Bingo what's the date code on your new battery?

I don't really know 
I couldn't find any sensible printing saying that.

/Bingo

[nukie]

Have a look at the original yellow cell, it is usually printed on the battery sleeve or stamped letters. Or contact your seller for date code. I know Sanyo usually has date code on the battery sleeve.

[free_electron]

I was just wondering if its possible to build an adaptor to read the contents of the memory. So you could back it up

You can dump it through gpib....

[eliocor]

I was just wondering if its possible to build an adaptor to read the contents of the memory. So you could back it up

You can dump it through gpib....

Please can you state the GPIB commands required to dump the calibration parameters?
I have taken a look to the Operator's and Service manuals with no avail....
Manuals at the following link

[bingo600]

I was just wondering if its possible to build an adaptor to read the contents of the memory. So you could back it up

You can dump it through gpib....

Isn't that only the 3458A ?

I have never heard about a "hidden command" for the 3478A , or for my upcomming 3457A (hint..hint)

/Bingo

[radiogeek97]

well folks I found a resonably priced 3478a on fleabay for 99$ including shipping.  It arrived the other day and I just replaced the battery sucessfully   The battery installed in it was a saft LX1634, i measured the voltage across the battery and it was about 3.04xxvdc  the voltage across the c510 cap was about 2.8xxxvdc.  I installed a battery pack across c510 and I left the unit under power.  I used my gas soldering iron and took my time.  Stupid design but I am hopefully good for many years now.  The voltage across the c510 post replacement was 3.04xxx so there was a noticeable boost in voltave with the new battery.  The red and black tape was to remind me of which end was which I didn't want to take any chances on shorting anything.  Thanks to dave and all the rest of you for the valueable info.   

PS has anybody a link on the adaptors to allow me to use my fluke and or pamona leads on this?  I hate to cut a $$ pair of leads.  I saw a link somewhere on here but cant find it anywhere not.

take care all
john

[Monkeh]

I have no idea where else stocks them, but: http://www.rapidonline.com/cables-connectors/4mm-shrouded-socket-adaptors-63902/

[alm]

I think Frankie (iloveelectronics on this forum) sells them. Send him a PM and you should get a better price than in his EBay store. Pomona also sells them, but at quite a high price if I remember correctly.

[bingo600]

I might like some too ...

For my 3478A , and my newly arrived 3457A

Maybe Frankie can chip i here

/Bingo


Ps: I just bought batts for the 3457A , i might start another thread on that one ...

 

[radiogeek97]

digi-key has what looks like an exact fit the batteries were only like 5 bucks each however the shiping fedex or ups was 10$ i told the lady forget it.  upps wont take lithium batteries so you are stuck with paying a premium

[iloveelectronics]

I might like some too ...

For my 3478A , and my newly arrived 3457A

Maybe Frankie can chip i here

/Bingo

I hope it is ok to post a link to my eBay store here in this case. Here is the shrouded to unshrouded banana adapter: http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=200904597758

I do offer 7% discount to all members who buy direct from me outside of eBay, as I will save some eBay fees that way. Just PM me what you want and your paypal address etc. Thanks!

Cheers,
Franky

[radiogeek97]

just recieved my adaptors today  Thanks 

[BillyD]

Sorry for going a little off topic here, but this made me curious. Given that the meter is basically screwed if this battery dies, is there any safeguard against this happening? i.e. do you get any sort of low battery warning or equivalent before it's too late?

[nukie]

Microbattery sells them very good international shipping rates.

[nukie]

Send it in for calibration, or replace battery every 8 years or so. Note battery date code.

Sorry for going a little off topic here, but this made me curious. Given that the meter is basically screwed if this battery dies, is there any safeguard against this happening? i.e. do you get any sort of low battery warning or equivalent before it's too late?