Author Topic: Agilent 34970A errors and battery replacement  (Read 11352 times)

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Offline plantgrower

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Agilent 34970A errors and battery replacement
« on: June 12, 2013, 11:13:36 am »
The problem is the unit gave error codes 742-746 and 749. The multimeter module was then put in another machine where it did not give these errors. It was then replaced into the original machine where it now does not give these errors.

I have tested the battery as shown in the Agilent service document 34970-90012 which reads 2.59v which is below the 2.7v at which the document says to replace it. Could this have been the cause of the errors ?

Could someone please tell me a suitable battery to use to replace it with and what sort of solder to use. I have some 63/37 lead solder is that ok ? Any tips on the procedure to remove the old battery ?

Do I need to run any procedures to undo original errors ?

many thanks

 

Offline bingo600

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Re: Agilent 34970A errors and battery replacement
« Reply #1 on: June 12, 2013, 11:57:38 am »
Outch ....

This indicates that you have lost all the calibration data
http://www.pmelforum.com/index.php?topic=1237.0

Pg. 318
http://docs-europe.electrocomponents.com/webdocs/0d87/0900766b80d870bd.pdf

/Bingo
 

Offline plantgrower

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Re: Agilent 34970A errors and battery replacement
« Reply #2 on: June 12, 2013, 01:56:04 pm »
Thanks for replying. I had found those two docs.

It no longer shows these errors and a self test PASSes.

Someone in the first link mentions a METCAL  automated adjustment procedure for this. Does anyone have something like this or some instructions for a newbie to follow.
 

Offline bingo600

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Re: Agilent 34970A errors and battery replacement
« Reply #3 on: June 12, 2013, 02:09:16 pm »
The METCAL was mentioned in the first link i posted.

And that forum belongs to
Quote
This is a site dedicated to the Air Force 2P0X1 - Precision Measurement Equipment Laboratory (PMEL)

The cost of the equipment to (correctly) calibrate a 6½ digit meter , would probably pay for lot's of 34970A's

Ohh ...
Did you change the battery ?

I wouldn't expect it to just disappear , unless you invoked some kind of calibration procedure.
And that would be a short joy , if you have a worn battery.

/Bingo
 

Offline plantgrower

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Re: Agilent 34970A errors and battery replacement
« Reply #4 on: June 12, 2013, 02:26:51 pm »
I haven't changed the battery yet.

No errors are showing.

Please could any one who has some experience with this piece of equipment or similar offer advice.

 

Offline free_electron

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Re: Agilent 34970A errors and battery replacement
« Reply #5 on: June 12, 2013, 03:13:25 pm »
Run the extended selftest. Hold the shift key while pressing power on. Keep holding ot until the machine beeps. Takes a good 5 seconds. Then it will run the extended selftest. That takes avout 20 seconds. See what happens then.

The errors you describe are most commonly cal memory corruption or failure. There is a 24f02 f-ram device on the multimeter card. These die over time. Digikey has them. IT NEEDS TO BE THE F-RAM VERSION ! Standard 24c02 eeprom does not work (fram has no erase cycle)
 You also need the image of a good fram.  I have working images. Once the fram is programmed solder it down. And restart the machine. You can now run the calibration.

Testing the dmm module in a different machine means nothing. If the other machine never had the dmm it is disabled in the system menu. You need to re-eanble it or no tests will be performed.

The dmm module is as accurate as a 34401. It is essentially the same guts in a different package.

The battery is a 1/3 a size. 3 volt lithium manganese cell with 3 pins. To desolder : desolder the end with 1 pin first. Heat the pin at the backside of the board while pullin on the battery at the other side.
Then heat the other two pins one by one while pulling. Clean up the holes with solderwick (chemtronics is ,by far, the best brand)

When installing a new battery : poke the two pins of one side through first, then poke the last one.
Solder one pin at a time

Make sure your soldering iron, nor solder does not touch anything else. If you short these batteries you may create catastrophical damage. The lithium cell can deliver multiple amperes when shorted, frying the traces on the board ....

When you remove the old cell. See if it has leaked .. If it has: clean up with alcohol before soldering.
The crystal growth is flammable and it will burn and spatter when soldering. It will also eat the traces on the board. But since you dont have communication errors or the dreaded double-beep at powerup( front panel not found) i suspect bo leakage.

The dreaded double beep is because two traces under the battery are damaged( eaten away) and the main cpu cannot talk to the front cpu. So it gives two long beeps and that's it.

Self calibrating the machine can't be done. You most likely don't have the equipment to do it. The calibration procedure is in the service manual. It takes about half an hour to do manually. A few minutes automatic . In either case you need a reference meter (3458) and some signal sources .
The 3458 alone will cost 10x more than the 34970a. You also need a 34901 plugin ( the relay multiplexer with 4 wire ohms and ampere range.

Callabs will calibrate the 34970 for about 75$.
« Last Edit: June 12, 2013, 03:21:41 pm by free_electron »
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Offline plantgrower

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Re: Agilent 34970A errors and battery replacement
« Reply #6 on: June 12, 2013, 04:00:04 pm »
Run the extended selftest. Hold the shift key while pressing power on. Keep holding ot until the machine beeps. Takes a good 5 seconds. Then it will run the extended selftest. That takes avout 20 seconds. See what happens then.

Sorry should have explained I have already done this and have just repeated the extended self test a couple of times it no longer brings up any errors.

Quote
The errors you describe are most commonly cal memory corruption or failure. There is a 24f02 f-ram device on the multimeter card. These die over time. Digikey has them. IT NEEDS TO BE THE F-RAM VERSION ! Standard 24c02 eeprom does not work (fram has no erase cycle)
 You also need the image of a good fram.  I have working images. Once the fram is programmed solder it down. And restart the machine. You can now run the calibration.

What are some less common reasons, oxidation on cables that connect the modules that unplugging and plugging could have removed ?
Can't find any 24f02 devices when I search at digikey is this the correct model no ?
Quote

Testing the dmm module in a different machine means nothing. If the other machine never had the dmm it is disabled in the system menu. You need to re-eanble it or no tests will be performed.


The machine it was tested in had a working dmm unit taken out and this unit put in to test.

Quote

The battery is a 1/3 a size. 3 volt lithium manganese cell with 3 pins. To desolder : desolder the end with 1 pin first. Heat the pin at the backside of the board while pullin on the battery at the other side.
Then heat the other two pins one by one while pulling. Clean up the holes with solderwick (chemtronics is ,by far, the best brand)

When installing a new battery : poke the two pins of one side through first, then poke the last one.
Solder one pin at a time

Make sure your soldering iron, nor solder does not touch anything else. If you short these batteries you may create catastrophical damage. The lithium cell can deliver multiple amperes when shorted, frying the traces on the board ....

If I had valid memory backed by the battery would I need to worry about losing the values in the memory when changing batteries?
Do you have a link to a suitable battery on digikey or such.
 Is there an order to solder the pins with the  new  battery ?


Many thanks for all the help. much appreciated  :)
« Last Edit: June 12, 2013, 06:20:55 pm by plantgrower »
 

Offline free_electron

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Re: Agilent 34970A errors and battery replacement
« Reply #7 on: June 12, 2013, 07:42:58 pm »
the battery only holds accumulated measurement data. calibration data is stored in the ferro ram.
if the battery gets too low to meter will not power up at all.

if you have replugged the dmm module you need to go in the menu and re-enable it. removing it disables the module. plugging it in does not automatically re-enable ! meny - system menu - dmm - enable dmm
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Offline plantgrower

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Re: Agilent 34970A errors and battery replacement
« Reply #8 on: June 13, 2013, 06:30:06 am »
Thanks for that. The DMM was disabled I have now enabled it and run the extended self test a couple of times and it still shows PASS.

Is it possible there was another fault other than you have suggested such as a loose/oxidized cable and unplugging replugging has fixed this issue ?

Are there any other checks I can run ?

many thanks
« Last Edit: June 13, 2013, 10:26:38 am by plantgrower »
 

Offline plantgrower

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Re: Agilent 34970A errors and battery replacement
« Reply #9 on: June 14, 2013, 09:23:58 am »
Thanks free_electron now when I run the self test test on every run it returns the errors 742, 743, 744, 745, 746 and 749.

I am now trying to get a refund on this unit from my ebay seller.

Many thanks for the heads up on enabling the DMM. I thought the person selling me this unit knew what they were doing with the equipment but obviously not.
 

Offline free_electron

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Re: Agilent 34970A errors and battery replacement
« Reply #10 on: June 14, 2013, 01:54:06 pm »
Thats corrupted cal memory. I can fix those.
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Offline plantgrower

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Re: Agilent 34970A errors and battery replacement
« Reply #11 on: June 14, 2013, 03:48:32 pm »
>Thats corrupted cal memory. I can fix those.

Can you please tell me how ? Does it involve soldering a new chip. I couldn't find that f-ram version only the eeprom version on digikey.

I presume it also involves the machine being recalibrated.

If you could tell me what to do it may be worth having a go rather than sending it back.
 

Offline free_electron

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Re: Agilent 34970A errors and battery replacement
« Reply #12 on: June 14, 2013, 06:13:08 pm »
It involves replacing 1 chips programmed with a known good image. part number is FM24C04B-G
Then a recalibration is in order. it may still fail calibration if there is really a defect on the dmm card. but out of the 8 machines I fixed I've only had one with a broken card. The rest were all revived.


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Offline plantgrower

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Re: Agilent 34970A errors and battery replacement
« Reply #13 on: June 14, 2013, 07:07:12 pm »
How do I program the chip with the image ?

I paid £147/230USD for this machine I think its just seven years old. It looks immaculate on the inside very good on the outside. The person selling these had quite a few to sell and this was the only machine with a problem. The others he sold for £290/454USD.

Sounds like it may be worth trying to repair it. Agilent want a lot more than 75USD to calibrate it though more like 180USD.

Thanks for all the help.
« Last Edit: June 14, 2013, 07:15:29 pm by plantgrower »
 

Offline free_electron

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Re: Agilent 34970A errors and battery replacement
« Reply #14 on: June 14, 2013, 07:27:51 pm »
you need an eeprom programmer that can handle the frams ... and the image file.
I can send you a programmed fram if you want. but you will have to wait a few weeks..
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Offline plantgrower

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Re: Agilent 34970A errors and battery replacement
« Reply #15 on: June 14, 2013, 10:15:09 pm »
Thanks for the offer I am in the UK. The eeprom programmers I looked at were in the low hundreds I don't know which programmer you have.

Waiting a few weeks wouldn't be a problem.
 

Offline free_electron

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Re: Agilent 34970A errors and battery replacement
« Reply #16 on: June 15, 2013, 12:42:40 am »
not all programmers know how to do the FRAM's.

that chip is small enough it can go in an envelope. i'll get you one. but like i said. it's gonna be a few weeks.
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Offline plantgrower

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Re: Agilent 34970A errors and battery replacement
« Reply #17 on: June 16, 2013, 10:55:52 pm »
Many thanks. I'd like to take you up on your generous offer please.

If the machine sometimes returns PASS on the extended self test is this indicative of the FRAM chip starting to fail or of a bigger problem with the DMM card ? It seems more likely to return PASS when it has been off for an extended period of time. When it  then starts to return FAIL it never shows PASS again until it has been off for an extended period.

Is it ok if  I pm you with my contact details ?
« Last Edit: June 17, 2013, 09:17:03 am by plantgrower »
 

Offline free_electron

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Re: Agilent 34970A errors and battery replacement
« Reply #18 on: June 17, 2013, 11:53:38 am »
Hmmm. That is a behavior i have not seen yet...
Start with swapping the battery. It may not come out of reset properly ....

If that doesnt work ill send you a new FRAM.

I have those batteries as well, but shipping that to uk is going to be a nightmare...
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Offline plantgrower

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Re: Agilent 34970A errors and battery replacement
« Reply #19 on: June 17, 2013, 04:03:31 pm »
The machine gives three short beeps at normal power up and a long beep and then three short beeps when I run an extended test.

I've had the dmm unit out and checked the battery 2.9v and in good condition so I don't think its that. Its also a short cylinder that has two prongs one either side not three prongs.

This machine PASSed three times in a row this morning but none since ?

Is it possible the fram has just started going bad as I was told these machines were in use not that long ago or is the error likely to be else where ?
« Last Edit: June 17, 2013, 06:21:46 pm by plantgrower »
 

Offline free_electron

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Re: Agilent 34970A errors and battery replacement
« Reply #20 on: June 17, 2013, 11:43:49 pm »
The three beeps on powerup are errors.

At powerup there should be only one short beep. So it looks like the FRAM is shot all right.
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Offline plantgrower

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Re: Agilent 34970A errors and battery replacement
« Reply #21 on: June 18, 2013, 10:56:48 am »
Edit :Now this machine is mostly PASSing how can that be ? Is it possible it really is a faulty lithium battery I have read in the manual that the battery is used at boot and the battery has dropped 0.02v in 24 hours so I think it may well be that? The battery in my machine is a Panasonic BR-2477A/VAN which digikey uk thankfully stock.

 Do these fram chips fail in this fashion I have been unable to find anything or is there another possible reason for the failure ?

I have an oki metcal sp200 iron with a fine chisel tip. I have used it to solder chips this small but that was on a new board.

Is it possible to use some solder wick and iron to remove the chip or do I need a hot air station ?

many thanks for all the help
« Last Edit: June 20, 2013, 09:48:10 am by plantgrower »
 

Offline N0_eq_kTBR

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Re: Agilent 34970A errors and battery replacement
« Reply #22 on: June 28, 2013, 10:26:32 pm »
Thanks.

Watched the 34970A slowly die and set it aside until I could afford a replacement.
As I recall, factory wanted $850 for replacement and a tech rental shop was offering $750 w/ 34902A earlier this year.

Somehow the other day ended up here.
Battery voltage read 0.15V.

Under $10 for new battery from Mouser.

Un-soldering w/Pace station. 
Tip touched round hole next to pin and spark blew all the solder out around terminal. 

Ohmmeter readings show that that hole is connected to the terminal????  Like the + terminal is connected to its close hole.

Judiciously replaced the battery and back in operation.
 

Offline plantgrower

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Re: Agilent 34970A errors and battery replacement
« Reply #23 on: July 20, 2013, 05:03:35 am »
Yes my battery has rapidly declined since. Once they start to go they rapidly decline.

I am waiting for my battery from digikey then I will sell it.

If anyone in the UK is interested in a pristine Agilent A34970a 7 years old with DMM and a new battery just installed please contact me.
 

Offline free_electron

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Re: Agilent 34970A errors and battery replacement
« Reply #24 on: July 20, 2013, 02:41:09 pm »
Thanks.

Watched the 34970A slowly die and set it aside until I could afford a replacement.
As I recall, factory wanted $850 for replacement and a tech rental shop was offering $750 w/ 34902A earlier this year.

Somehow the other day ended up here.
Battery voltage read 0.15V.

Under $10 for new battery from Mouser.

Un-soldering w/Pace station. 
Tip touched round hole next to pin and spark blew all the solder out around terminal. 

Ohmmeter readings show that that hole is connected to the terminal????  Like the + terminal is connected to its close hole.

Judiciously replaced the battery and back in operation.

That spark is because you had a leak. You need to clean the board under the battery ! The battery fluid will eat the traces ...
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