agilent 3458A multimeter value

[eurofox]

Hi nV freaks,

What is the value for a second hand Agilent 3458A for a unit that was not used very much, look like new and still have a valid calibration?
I have a proposition for such a unit but it is hard to check the real value.

eurofox

[saturation]

Working to factory spec with a valid calibration?  ~$5000 in the USA.

[EEVblog]

They have gone for as little as $2500 in the past I believe, and I think this is close to what Martin Lorton paid for his. But most go for a lot more than that, probably double if you wait long enough and have a good ad.

[eurofox]

Thanks for input

eurofox

[saturation]

Sample ranges for units sold on US eBay ~ 3-4 months ago for USA:

http://www.ebay.com/sch/i.html?_sacat=0&_from=R40&LH_Complete=1&LH_Sold=1&_nkw=3458a&_sop=3

[orin]

Hi nV freaks,

What is the value for a second hand Agilent 3458A for a unit that was not used very much, look like new and still have a valid calibration?
I have a proposition for such a unit but it is hard to check the real value.

eurofox

Bear in mind that Agilent charges $2660 flat rate to fix them.  Any error and I mean any error in self tests or on any range reduces the value by $2660.  Once you've paid the $2660 though, a maintenance contract is relatively cheap at $180 per year (so add that to the budget).

Given that 'working' units have been going for $4000 to $5000 on ebay, I'd pay no more than $4000 for a working calibrated unit.  $1500 for a 'parts' unit.  Yes, the 'parts' units go for more than that, but too much of a risk IMO.

Calibration will cost $650 minimum at Agilent - you don't want to get one of these calibrated at Joe's Discount Cal Lab!

 

[eurofox]

Hi guy's,

And what about  the KEITHLEY 2002 - 8,5 Digits compared to the agilent 3458A, it is a more modern version and not so big.
Someone  got experience with this one?

eurofox

[quarks]

Hello eurofox,

have a look at

https://www.eevblog.com/forum/testgear/8-5-digit-dmm/msg258880/#msg258880

I also have somewhere downloaded a comparison document between 3458A and 2002.  If you cannot find it, I can send it.

Bye
quarks

Edit: here is a link to the document
http://www.bnl.gov/cad/sns/test_report/Comparison%20of%20Keithley2002%20and%20HP3458A%20DMM.doc

[eurofox]

Hello eurofox,

have a look at

https://www.eevblog.com/forum/testgear/8-5-digit-dmm/msg258880/#msg258880

I also have somewhere downloaded a comparison document between 3458A and 2002.  If you cannot find it, I can send it.

Bye
quarks

Edit: here is a link to the document
http://www.bnl.gov/cad/sns/test_report/Comparison%20of%20Keithley2002%20and%20HP3458A%20DMM.doc

Thanks

[ben_r_]

Wow, that is one pricy meter! But 8.5 digits?! Crazy!

[mos6502]

What would you need that kind of precision for, apart from experimental physics?

Once you go to that level, you pretty much have to control all the environmental variables, temperature, humidity ... and everything would have to be super clean.

[Dave]

What would you need that kind of precision for, apart from experimental physics?

Once you go to that level, you pretty much have to control all the environmental variables, temperature, humidity ... and everything would have to be super clean.

Calibration.

[ben_r_]

Yep, thats the only thing I could think of, calibration.

[staxquad]

Wow, that is one pricy meter! But 8.5 digits?! Crazy!

$3 with free shipping is not pricy   

Unit is Calibrated and Guaranteed Working

Certificate of Calibration Provided With Instrument

(calibration expires 9/17/14)

including option 002

[quarks]

$3 with free shipping is not pricy   

Unit is Calibrated and Guaranteed Working

Certificate of Calibration Provided With Instrument

(calibration expires 9/17/14)

including option 002

that looks really strange, but when you look at the description there is a 3500$ price tag
http://www.ebay.com/itm/Agilent-HP-3458A-Digital-Multimeter-8-Digit-w-001-002-700-ID-25159-/190907939747?hash=item2c72fffba3

[eurofox]

Hi Guy's,

Any idea how much I should propose to pay for a 3458A with bad NVRAM?
Where can I get the latest firmware?

Is there any application to read the data from the NVRAM over the GPIB and store it to a file in HEX format?
I have now the USB-GPIB interface.

Thanks 

eurofox

[ManateeMafia]

If you don't already know, the calibration constants are stored in one of the three NVRAM modules inside the meter. You should replace all three at a time.
Once they are replaced, you will lose your calibration unless you can salvage the contents of U132 with a programmer.
Also, the NVRAM are not socketed, but should have them added using high quality mill-max style sockets.

If you cannot save the cal data, you should add in the cost of a full calibration as a minimum. Plus, add a new DS1220Y, two DS1235Y, sockets, labor to replace.

Have you performed a self-test and ACAL ALL on this unit? A passing self-test does not guarantee a passing ACAL ALL.
One of my units failed ACAL due to a bad capacitor, but passed self-test all day long.

A passing ACAL does not mean it will pass full calibration, but a failing test probably means a full repair cost. Agilent's repair price also includes a calibration afterward.

[quarks]

Hi Guy's,

Any idea how much I should propose to pay for a 3458A with bad NVRAM?
Where can I get the latest firmware?

Is there any application to read the data from the NVRAM over the GPIB and store it to a file in HEX format?
I have now the USB-GPIB interface.

Thanks 

eurofox

I guess it is an old unit, because the batteries in the NVRAMs are usually good for min. 10 years. If  battery in the DS1220 is already dead then the unit has lost the cal data and you need new calbration. If the data is still there you can either carefully unsolder the chips and make a copy with a programmer or you can try MREAD via GPIB (look for details in voltnuts).

[casinada]

There is no way that the unit went for $3 and free shipping considering what the other things from the seller go for. That would be like the deal of the millennium

[PaulAm]

The seller probably cancelled the deal claiming the meter was previously sold, or disappeared from his stock.

That's happened to me a couple of times.

[eurofox]

I guess it is an old unit, because the batteries in the NVRAMs are usually good for min. 10 years. If  battery in the DS1220 is already dead then the unit has lost the cal data and you need new calbration. If the data is still there you can either carefully unsolder the chips and make a copy with a programmer or you can try MREAD via GPIB (look for details in voltnuts).
[/quote]

I just wonder if data is still there with the error message and if it make sense to develop an application to read the data over GPIB because I don't think that MREAD command will create a file in Hex able to load in a new NVRAM, this mean that some code should be written in VB or C using the Agilent library.
Correct me please if I'm wrong.

Thanks for input 

eurofox

[staxquad]

The seller probably cancelled the deal claiming the meter was previously sold, or disappeared from his stock.

That's happened to me a couple of times.

looking at his completed listings, he re-listed the unit and took a best offer (so you all didn't miss the deal of the millennium)

[quarks]

I just wonder if data is still there with the error message and if it make sense to develop an application to read the data over GPIB because I don't think that MREAD command will create a file in Hex able to load in a new NVRAM, this mean that some code should be written in VB or C using the Agilent library.
Correct me please if I'm wrong.

Thanks for input 

eurofox

Do you know the exact error message?
If I remember right the MREAD and my direct Eprom chip read out was identical.

[eurofox]

Do you know the exact error message?
If I remember right the MREAD and my direct Eprom chip read out was identical.


The error message is "RAM TEST 2 HIGH", I suppose it is the high part of the NVRAM since memory is mapped into low/high with 2 NVRAM's.
The instrument in completely locked.

With respect to use undocumented MREAD, I found some information (From POUL HENNING):

The 3458A has a number of undocumented commands, amongst these:

   XYZZY      (try it :-)

   MREAD
   MWRITE
   JSR

MREAD allows you to read one 16bit memory word, for instance:

   MREAD   4
   MREAD   6

will get you the two halfwords of the RESET vector.

The Calibration NVRAM is located in the top byte of the memory at
address 0x60000...0x60fff, so by issuing 2048 GPIB commands:

   MREAD 393216
   MREAD 393218
   ...
   MREAD 397308
   MREAD 397310

I think the only way is to write code that open a file code.hex, loop from the beginning till the end of the NVRAM, use MREAD, apply eventually conversion to it in Intel Hex format, write into the file.
This file could be used in theory to write into a new NVAM.


eurofox

[Dr. Frank]

if the calram is ok, you may buy the instrument, that's where the money is in.
Forget the working ram, 32k*8. Its content can be restored easily.
You need GPIB, a program to read out, desoldering tools & skills and a programmer to transfer the CALMEM to a new one. (Which you may buy easily also)

I did it successfully, Quarks and others also.

Frank

[eurofox]

if the calram is ok, you may buy the instrument, that's where the money is in.
Forget the working ram, 32k*8. Its content can be restored easily.
You need GPIB, a program to read out, desoldering tools & skills and a programmer to transfer the CALMEM to a new one. (Which you may buy easily also)

I did it successfully, Quarks and others also.

Frank

Hello Frank,

Did you write such a program?
If yes could you be so kind to share it?

Thanks for the info 

eurofox

[eurofox]

Since the instrument is locked because of the error it is not possible to know or change the GPIB address, I try with address 22 that is the factory default but no communication possible. 
I use the Agilent Connection Expert but cannot find an IVI compatible driver from Agilent only NI drivers seems to be available. 

This high tech multimeter drive me creasy     

eurofox

[alm]

Why would you need an instrument driver? It's not likely to support MREAD anyhow. Just sending ID? to its address (pretty sure the 3458A doesn't support the SCPI *IDN? command that the Agilent software probably sends by default) and it should return "HP 3458A". I haven't used the Agilent GPIB software for a long time, but I'm pretty sure it has a "send GPIB command" function somewhere. There are only 30 addresses to try.

[eurofox]

Sorry for my GPIB ignorance, I never used before and just bought a USB-GPIB interface 2 weeks ago.
Agilent explorer scan and detect the instruments connected, I have other instruments and did not give the GPIB address but detected without problem, only the 3458A seems to be an exception.

eurofox

[Dr. Frank]

Since the instrument is locked because of the error it is not possible to know or change the GPIB address, I try with address 22 that is the factory default but no communication possible. 
I use the Agilent Connection Expert but cannot find an IVI compatible driver from Agilent only NI drivers seems to be available. 

This high tech multimeter drive me creasy     

eurofox

Hi,

does that mean, that you have bought the unit and have it on your bench?
What's the vintage / date code?

The 3458A GPIB is very well designed, and can be accessed very easily, under normal conditions.
Perhaps the "agilent expert" does not work with the GPIB/USB adapter.

To find out the GPIB address, use the front panel keypad.

(For sure you have downloaded the manual already)

Choose MENU FULL. Then ADDRESS? gives you the GPIB address, ADDRESS 22 sets it to the desired one.

If the unit fails with RAM TEST High, this should happen only on power up. If you then make a RESET from the front panel, the instrument should initialize the NVRAM (32k*8 ) with default values, and should then continue without further failure (until, of course, you repower the unit).
Address 22 should be default, otherwise change it.
If the error persists, perhaps the CAL memory is affected. So skip the unit, as the calibration is affected (Once again: what's the date code of the unit, or better, of the DALLAS chips inside?).

What do you mean that the unit is "locked"? The front panel menu should be accessible.

I don't know anything about your GPIB program, neither your GPIB/USB interface.
 
I have programmed mine in Pascal, and may publish the core code of the MREAD command usage for the CAL RAM, if you have the possibility to write a program on your own, in any other language, perhaps.
I cannot provide any GPIB adapter related code, because mine is written for the ancient CEC card, not NI or else.
So you have to adapt the appropriate GPIB drivers and functions on your own.

My program writes a hex and a binary file. Latter one can be directly used for an EPROM programmer to write the data to the new chip.
It's not possible to do that via MWRITE command.

The latest firmware 9,x can be bought at agilent, see their site for details, it's listed there, related to PC board revisions.
The update for the old version (6 EPROMs) cost about 202€, the single chip version about 22€.
Depends on the vintage of your unit.

After EPROM and NVRAMs are updated, the unit will be as good as new.

Frank

[eurofox]

Since the instrument is locked because of the error it is not possible to know or change the GPIB address, I try with address 22 that is the factory default but no communication possible. 
I use the Agilent Connection Expert but cannot find an IVI compatible driver from Agilent only NI drivers seems to be available. 

This high tech multimeter drive me creasy     

eurofox

Hi,

does that mean, that you have bought the unit and have it on your bench?
What's the vintage / date code?

The 3458A GPIB is very well designed, and can be accessed very easily, under normal conditions.

To find out the GPIB address, use the front panel keypad.

(For sure you have downloaded the manual already)

Choose MENU FULL. Then ADDRESS? gives you the GPIB address, ADDRESS 22 sets it to the desired one.

If the unit fails with RAM TEST High, this should happen only on power up. If you then make a RESET from the front panel, the instrument should initialize the NVRAM (32k*8 ) with default values, and should then continue without further failure (until, of course, you repower the unit).
Address 22 should be default, otherwise change it.
If the error persists, perhaps the CAL memory is affected. So skip the unit, as the calibration is affected (Once again: what's the date code of the unit, or better, of the DALLAS chips inside?).

What do you mean that the unit is "locked"? The front panel menu should be accessible.

I don't know anything about your GPIB program, neither your GPIB/USB interface.
 
I have programmed mine in Pascal, and may publish the core code of the MREAD command usage for the CAL RAM, if you have the possibility to write a program on your own, in any other language, perhaps.
I cannot provide any GPIB adapter related code, because mine is written for the ancient CEC card, not NI or else.
So you have to adapt the appropriate GPIB drivers and functions on your own.

My program writes a hex and a binary file. Latter one can be directly used for an EPROM programmer to write the data to the new chip.
It's not possible to do that via MWRITE command.

The latest firmware 9,x can be bought at agilent, see their site for details, it's listed there, related to PC board revisions.
The update for the old version (6 EPROMs) cost about 180€, the single chip version about 20€.
Depends on the vintage of your unit.

After EPROM and NVRAMs are updated, the unit will be as good as new.

Frank

Hi Frank,

Yes the instrument is on my bench and I have an option to buy it.

Shift RESET just illuminate all segments from the display, I assume it really make a reset but return with the same "RAM TEST 2 HIGH" error.
No way to enter an new GPIB address, instrument is locked, just accept a RESET
By locked I mean that there is no way to access the menu.

Date code from Dallas NVRAM is 8936D1 and 8946M, Rev of ROM 5.3, it looks like an instrument from the 1st year of production since they start in 1989.

I assume that all calibration data is lost and it is not a good idea to buy this instrument or maybe just for 200 Euros.

I can write code in assembler, C, Basic, VB and used in the past Pascal, if you can share the Pascal code it is welcome.

Thanks for your sharing experience and support.

eurofox

[Dr. Frank]

Hard to figure out, if replacing those 3 NVRAMs will heal the unit.
Perhaps something in the hardware is faulty, also.

This LOCK is unusual, see manual for the LOCK command.

These NVRAMs do not cost that much, but if the calibration is lost, that'll be at least 500€ extra to get an official recal by agilent after your repair.
So, the risk would be on you, if you keep and try to repair.

Therefore the unit in its current state is worth about 1500€ at most, I would guess.

I append the TP code fragments.

Frank

[alm]

Agilent explorer scan and detect the instruments connected, I have other instruments and did not give the GPIB address but detected without problem, only the 3458A seems to be an exception.

Like I said, the Agilent explorer probably sends the *IDN? command to all addresses to probe for instruments. *IDN? is an SCPI command, which I'm pretty sure the 3458A doesn't support. ID? would be the equivalent 3458A command, but you'd have to send this manually. I'm not sure how likely it is for GPIB to work if the front panel controls fail, however.

[ManateeMafia]

If you press the Blue shift button and then press the - (error) key it will show the first error. The little "err" annunciator should be lit on the display.
Then you press the shift button again and then press backspace (clear) it will delete the error. Then repeat the process through all other errors.
The err annunciator should disappear after stepping through all the errors.

Write them down and post them including the error numbers. It sounds like there are more logged errors, it is probably showing the RAM Test 2 High error since it is the first failure.

I have seen similar issues with either a bad A/D converter board or AC converter board that failed POST and would not go any further, except I believe RESET was usable.

The 3458A assembly level troubleshooting guide lists the error messages and probable causes starting on page 73. It is a board level troubleshooting guide, but should give you an idea of what may be the cause of failure. Of course, power supplies are easy to test too.

[eurofox]

Agilent explorer scan and detect the instruments connected, I have other instruments and did not give the GPIB address but detected without problem, only the 3458A seems to be an exception.

Like I said, the Agilent explorer probably sends the *IDN? command to all addresses to probe for instruments. *IDN? is an SCPI command, which I'm pretty sure the 3458A doesn't support. ID? would be the equivalent 3458A command, but you'd have to send this manually. I'm not sure how likely it is for GPIB to work if the front panel controls fail, however.

From Agilent Explorer I can send a command and I try with other instruments and it is working but the unit should be know by the system at least by GPIP address and this is not working, I try manually all addresses.
The unit only accept RESET from the front panel.

Verry frustrating 

Eurofox

[ManateeMafia]

I read service note 3458A-04A that states during a power-on sequence or reset, a subroutine at location SUB 0, will run. If you have one that sets "LOCK ON" it could give you the same indication.

You can run the SCRATCH command when you get the GPIB interface working, this will delete all subroutines.

You probably don't have this issue based on the age of your NVRAM, but worth a shot anyway.

[alm]

If you want an easy scripting interface for GPIB, the EZ-GPIB software might work for you. It's a Pascal-like scripting language that's fairly popular for hobbyist instrument control on the cheap. It would be easy to write a program to loop through addresses 1-30, send ID? and read a response.

[Dr. Frank]

Agilent explorer scan and detect the instruments connected, I have other instruments and did not give the GPIB address but detected without problem, only the 3458A seems to be an exception.

Like I said, the Agilent explorer probably sends the *IDN? command to all addresses to probe for instruments. *IDN? is an SCPI command, which I'm pretty sure the 3458A doesn't support. ID? would be the equivalent 3458A command, but you'd have to send this manually. I'm not sure how likely it is for GPIB to work if the front panel controls fail, however.

From Agilent Explorer I can send a command and I try with other instruments and it is working but the unit should be know by the system at least by GPIP address and this is not working, I try manually all addresses.
The unit only accept RESET from the front panel.

Verry frustrating 

Eurofox

Well I understand the dilemma.
3458A would definitely respond to ID? with "HP3458A", but if it does not respond to ANY GPIB address..
And yep, the 3458A does not understand SCPI.

Pls. inspect the volt-nuts mailing list, April 2013.
There was the same error, RAM HIGH 1, same instrument vintage, with lockout of keyboard.
Those old firmware versions maybe leave the instrument in a totally puzzled state, if the NVRAM content is corrupted, instead of simply initializing to default parameters, what happened initially when I powered on after insertion of the fresh, blank 32k*8 RAMs. I've got late firmware 8,2.

But I don't know, what was the other solution, perhaps you ask that colleague volt-nuts.

PS: Pls. also try the TEST key, if that is accessible via keyboard.

Frank

[eurofox]

Agilent explorer scan and detect the instruments connected, I have other instruments and did not give the GPIB address but detected without problem, only the 3458A seems to be an exception.

Like I said, the Agilent explorer probably sends the *IDN? command to all addresses to probe for instruments. *IDN? is an SCPI command, which I'm pretty sure the 3458A doesn't support. ID? would be the equivalent 3458A command, but you'd have to send this manually. I'm not sure how likely it is for GPIB to work if the front panel controls fail, however.

From Agilent Explorer I can send a command and I try with other instruments and it is working but the unit should be know by the system at least by GPIP address and this is not working, I try manually all addresses.
The unit only accept RESET from the front panel.

Verry frustrating 

Eurofox

Well I understand the dilemma.
3458A would definitely respond to ID? with "HP3458A", but if it does not respond to ANY GPIB address..
And yep, the 3458A does not understand SCPI.

Pls. inspect the volt-nuts mailing list, April 2013.
There was the same error, RAM HIGH 1, same instrument vintage, with lockout of keyboard.
Those old firmware versions maybe leave the instrument in a totally puzzled state, if the NVRAM content is corrupted, instead of simply initializing to default parameters, what happened initially when I powered on after insertion of the fresh, blank 32k*8 RAMs. I've got late firmware 8,2.

But I don't know, what was the other solution, perhaps you ask that colleague volt-nuts.

PS: Pls. also try the TEST key, if that is accessible via keyboard.

Frank

Frank,

Thanks for support, I think this machine need a full service, new NVRAM, new Firmware and new calibration and I really wonder if the final cost will not be more than the market value, on ebay France at least 2 times working units sold for +/- 2000 Euros.
And finaly there could be another hardware problem as well

eurofox

[eurofox]

If you want an easy scripting interface for GPIB, the EZ-GPIB software might work for you. It's a Pascal-like scripting language that's fairly popular for hobbyist instrument control on the cheap. It would be easy to write a program to loop through addresses 1-30, send ID? and read a response.

Hi Alm,

Thanks for the link I will try this tool.


eurofox

[eurofox]

Hello Volt Nuts,

Update of the HP3458A story.

I would like to thank Quarks for he’s kind support    and all others 

I could manage finally to get the instrument.

It is in a fair cosmetic condition, only small usage marks, after removing all labels and glue from calibration labels, the front panel is in mint condition. I hate all those labels on the front panel and sometimes when the instrument is defect they put it on the display. 

The LTZ1000 is covered by a plastic cap, is this done on all HP3458A because I could find some pictures on the net with the option 002 with this kind of protection?

I order 1 DS1220 and 2 DS1235Y, I will change them to DS1230Y.
I order a Geller Lab SVR-T that is on he’s way to spend one week in our customs.
I order a 10K resistor 0,005% / 0,05ppm/°C

I removed the 3 NVRAM without problem with my iron with pump, easy job, just 2-3 minutes for 1 NVRAM, no damage on PCB *.
Put 3 industrial gold plated sockets and solder them on the PCB and clean it.

I checked the DS1220Y by reading with my eprom programmer and is virtual empty, just a few random values. By using the test function it give an OK

I don’t really know what they do in the testing procedure, I suppose reading content, saving it to put back after test, writing FF, reading again and comparing if it is the same and write back the saved data.

By testing the 2 DS1235Y my programmer report that one is bad at a specific address. 

I got the ordered DS1220Y from Germany last week and put it in place  , still waiting for the DS1235Y from UK. 

I try to put the DS1235Y(s) back and depending of the position it give me an error HIGH or LOW and it could be logic if one is bad and detected by the test procedure.

I upgraded the firmware as well but nothing changed, instrument is still only accepting the SHIFT and RESET function.
I hope that there is no other issue after adding the 2 NVRAM.

I intend to do the following to calibrate it:

1/ I have 2 calibrated in metrology lab 6,5 digits meter, Agilent and Picostest (They have similar specifications), I have a DER DEE for the resistor test.
2/ I will measure the value (after warm up) of the resistor with the 2 6,5 digits meter and the DER DEE and make an average and this value with the resistor will be used to calibrate the HP3458A.
3/ Start the calibration with the copper wire, the 10V reference from Geller lab and the 10K precision resistor.
4/ I hope that this should finalize it. I will check the Agilent notes about the instrument.

I will update when I get the 2 missing NVRAM.

* Used wrist strap and safe table connection to ground.

eurofox

[ManateeMafia]

I am pretty sure all cal constants are stored on the DS1220. You will be able to verify that when you run through the calibration procedure.

I have seen the plastic caps on both the standard and opt002 reference boards. Look on the board for the part number. The standard reference is 03458-66509. The opt002 is 03458-66519.

You can skip the SCAL procedure unless you have a stable ac reference. It will be difficult to cal the ac unless you have a good source.

How do the power supplies look? Hopefully the unit did not spend a lot of time gathering dust.
If so, it could take about 6 weeks of sitting idle for the reference to settle down. There was an app note from HP on this. I cannot remember which one, I am not at home to give you the specifics.

[eurofox]

I am pretty sure all cal constants are stored on the DS1220. You will be able to verify that when you run through the calibration procedure.

I have seen the plastic caps on both the standard and opt002 reference boards. Look on the board for the part number. The standard reference is 03458-66509. The opt002 is 03458-66519.

You can skip the SCAL procedure unless you have a stable ac reference. It will be difficult to cal the ac unless you have a good source.

How do the power supplies look? Hopefully the unit did not spend a lot of time gathering dust.
If so, it could take about 6 weeks of sitting idle for the reference to settle down. There was an app note from HP on this. I cannot remember which one, I am not at home to give you the specifics.

I will check the option 002 based on the number you provide.
I have Fluke 510A AC Reference Standard that I have fixed and calibrated with my Agilent 6 1/2 digits, I can use this one if needed.
The unit is totaly clean inside virtual no dust at all.

eurofox

[TiN]

The LTZ1000 is covered by a plastic cap

That is not for protection, that's for temperature stabilization. Plastic cover is working similar to simple thermostat, to reduce temperature variation of reference.

Show us some nice internal pics

[Dr. Frank]

Hello Volt Nuts,

The LTZ1000 is covered by a plastic cap, is this done on all HP3458A because I could find some pictures on the net with the option 002 with this kind of protection?

I order 1 DS1220 and 2 DS1235Y, I will change them to DS1230Y.
I order a Geller Lab SVR-T that is on he’s way to spend one week in our customs.
I order a 10K resistor 0,005% / 0,05ppm/°C

I checked the DS1220Y by reading with my eprom programmer and is virtual empty, just a few random values. By using the test function it give an OK

By testing the 2 DS1235Y my programmer report that one is bad at a specific address. 

I try to put the DS1235Y(s) back and depending of the position it give me an error HIGH or LOW and it could be logic if one is bad and detected by the test procedure.

I upgraded the firmware as well but nothing changed, instrument is still only accepting the SHIFT and RESET function.
I hope that there is no other issue after adding the 2 NVRAM.

I intend to do the following to calibrate it:

1/ I have 2 calibrated in metrology lab 6,5 digits meter, Agilent and Picostest (They have similar specifications), I have a DER DEE for the resistor test.
2/ I will measure the value (after warm up) of the resistor with the 2 6,5 digits meter and the DER DEE and make an average and this value with the resistor will be used to calibrate the HP3458A.
3/ Start the calibration with the copper wire, the 10V reference from Geller lab and the 10K precision resistor.
4/ I hope that this should finalize it. I will check the Agilent notes about the instrument.

I will update when I get the 2 missing NVRAM.

eurofox

The LTZ1000A reference inside the HP3458A always has two plastic caps assembled, one on component side, one on soldering side, see picture. That's intended for thermal shielding. The references on the web without those caps need urgently an external case for shielding.

The DS1220 contains all calibration constants (253 EA, artifact calibration and autocal constants, see listing in cal manual, CAL? command).
This RAM is protected against erroneous writing, but the content can be read by undocumented MREAD command.

The DS1230/1235 RAMs store configuration information and macros.
And most important, this 32kx16 RAM space is the working RAM memory for the 68HC000 processor.

Therefore, if one of the RAMs has a hardware error, as you obviously determined by your programmer, the processor may get stuck.
At which memory location the error is detected?

Therefore, replacing them may really heal the problem.

If you also upgraded the firmware (ver. 9,x?), which removes many bugs, then you will have a very fine refurbished box.

Your description, how you want to calibrate the unit, is ok, but it's a fact that you will have lost accuracy of DCV and OHM , and also high frequency calibration (above 100kHz VAC).

Therefore, I hope you have not payed more than 2000€, better less, as the calibration data are lost.

Frank

[eurofox]

Hello Volt Nuts,

I still wait for the NVRAM from UK  , they promise to send me a new set free of charge.

@ TiN : I will make some pictures when the NVRAM’s arrive.
@ Frank : Picture of the error of the NVRAM in attachment, I copy the data from another working HP3458A into the new DS1220Y, this way I should have basic calibration data that of course is not from my instrument. Firmware is upgraded to 9.x.

I exchange the instrument with a working oscilloscope (I have 4 other scopes  ), if the instrument is working with the NVRAM and no other problem it is a good deal  , if not it is a very bad deal.

With respect to AC calibration I have all the instruments/tools needed just missing the thermal converter.
If I understood right what those thermal converters are doing is just converting the AC RMS into a DC value that is read by the instrument.
There are many discussions about converting RMS by mathematics or by this thermal system (resistor + thermocouple)
I have an idea of an alternative using a generator, a 6 ½ digits meter and a DC calibrator.

Connect the generator to the 6½ digits meter in AC, connect the DC calibrator to the HP3458A, follow the procedure from the calibration manual with the 3 VAC, 1VAC …. On the different frequency’s, put the value from the DC calibrator according the value from the 6½ digits meter.
I think worst case I will have an accuracy that is similar to the 6 ½ digit millimeter. I could use as well the output level from the generator but I suppose the HP meter will be more accurate.
If you have comment on the procedure please comment.

I got an email today from Agilent, they charge 623,08 Euros + 60 Euros for the carrier to pick-up the instrument + VAT.
Agilent is very dynamic over here, usually you get an answer on email in one hour and they are very service minded, already got free of charge a part of an instrument.

eurofox

[ManateeMafia]

The AC calibration requires a 100KHz, 2 MHz, and 8MHz reference. If your 6.5 digit meter is not spec'd for that input range, you probably won't want to waste your time with those steps.

You are not forced to do all the AC cal steps, but if you already have access to another 3458A, use it as a transfer standard. If not, just do the DC and resistance checks, then run ACAL AC.
If it passes, check the meter with whatever AC source you have for sanity checks. Some other people have had limited success with signal generators like the HP 3325A , but if you are already considering the Agilent cal, test the meter as best you can. Agilent will do the rest.

[Dr. Frank]

oK, the error is at 0805, that's a low address, I assume in the area the µP normally uses as working space. The setup and key programming will be on higher addresses.

I assume, the firmware tests the working space area for errors on bootup (test pattern R/W), and the setup area for integrity only.
After finding defect RAM cells, the instrument will go into hold mode, to not endanger the operation.

And I confirm exactly, what ManateeMafia already wrote.

Better let the instrument initialize the CALRam with default values, then calibrate as good as possible 10V and 10kOhm, and that's it.
Any other 6,5 digits instrument will not work at 2/8Mhz sufficiently well.

And the problem has nothing to do with the A/D of alternating signals, it's the AC preamplifier, which is calibrated by the SCAL commands.

The 3458A is very precise up to 100kHz without SCAL, and may measure accurately down to 20ppm or even better at audio frequencies, if you use e.g. Gods Program from agilent , written by Swerlein.

So, if you don't need ACV at frequenciy >100kHz, better leave the RAM alone.

I think, copying cal data from another 3458A might worsen things.

Frank

[Dr. Frank]

I order 1 DS1220 and 2 DS1235Y, I will change them to DS1230Y.


eurofox

Hello eurofox,

I hope you have ordered the DS1230Y - 150+, not the terminated DS1235Y?
You would either get"old", not "fresh" ICs, or it would be very difficult for the distributor to even source it.

Or did you order at MAXIM UK directly?

Recently, Maxim UK had 10 weeks lead time for the DS1230Y, so a colleague volt-nuts ordered instead at Mouser, who delivered within 1 week.

Frank

[eurofox]

Frank,

I order them from a supplier in UK, according the tracking number I should get them next Monday.

With respect to the calibration on the analog part I will follow your advice, I check the 6 1/2 digit meter and is not supporting AC in the requested frequency range for the calibration.

I just have to put the missing NVRAM and cross my fingers.

I will update next Monday when I get the NVRAM.

eurofox

[TiN]

This thread motivates me to dig into my Keithley's trying fix some
Reversing schematics. Layout is not reverse-friendly at all 

[eurofox]

This thread motivates me to dig into my Keithley's trying fix some
Reversing schematics. Layout is not reverse-friendly at all 

You are right, I get adicted to it and this particular instrument is quite unique, was designed 25 years ago and nothing really to replace it.

From time to time I buy from ebay defective instrument at very low cost and fix them.

[eurofox]

Hello Vot Nuts,

Today I got the 2 missing NVRAM .... after 2 long weeks waiting 

The good news is  it is working 

And a few other picture from inside the instrument like requested.

[eurofox]

Some more pictures

[quarks]

congratulations 

[Dr. Frank]

Calibrate and have fun! 

Frank

[ManateeMafia]

Congratulations.

Not a bad deal, a scope for a 3458A. It doesn't get much better than that.

Your zener reference could take a few weeks now to get stable. If you calibrate it now, you should compare it against your 10V reference every day until the readings remain fairly constant.

It took several weeks before my meter would stay close to zero with the inputs shorted with a copper wire across the inputs. I ran ACAL ALL a couple of times a day for several weeks, and I could see the zero drift less with each passing week. Temperature is also a big factor too. This thing is very sensitive to temp changes, even by a change of 1 deg. C

[eurofox]

The scope is an Agilent 500Mhz combi scope with all probes like new. I bought it because it was a good deal, I already have 4 scopes.

If I could not get the instrument working it was a very bad deal, I can say that the deal is fair for a working instrument.

I still have minor problems discovered with testing it, the keyboard key's 1234 are not responsive, 2 not responsive at all.

I'm afraid they use keys with carbon on the rubber key making a short on the pcb, maybe I'm wrong but will have to check it, but I suppose that Agilent can supply this kind of spare part.

eurofox

[Dr. Frank]

Your zener reference could take a few weeks now to get stable. If you calibrate it now, you should compare it against your 10V reference every day until the readings remain fairly constant.

It took several weeks before my meter would stay close to zero with the inputs shorted with a copper wire across the inputs. I ran ACAL ALL a couple of times a day for several weeks, and I could see the zero drift less with each passing week. Temperature is also a big factor too. This thing is very sensitive to temp changes, even by a change of 1 deg. C

That's absolutely not right, or not in that extreme, sorry.

The LTZ reference itself is stable within a few minutes. Afterwards it may drift a few tenths of ppm, or less. That's how my two external LTZ1000 behave @ 45°C.
For the 3458A it's hard to tell, how the LTZ behaves at 95°C, because normally you cannot measure the internal ref from outside, and the intial drift is determined totally by the gain resistors drift.

The 3458A as a whole only needs those 2..4h hours of warming up, 12..15°C max. difference of internal vs. room temperature.
Take care, that the difference is not greater, otherwise clean the fan filter. And put it on desk top, not in a rack for best metrological performance.

I always shut off the 3458A after a session.
When I power on again, it takes about 2h, and perhaps (not necessarily) an AUTOCAL, and then the instrument is back to a few 10nV zero reading, and Full Scale reading to tenths of ppm.
That does not take weeks, that's absolutely not correct!
Even after weeks of being shut off.

For precision measurements, half a day of stabilization is used.
Afterwards, Autocal is only necessary if Rt changes more than 1°C.

But you can measure such small effects only, if you have absolutely stable RT over a longer period of time, and if you have a source with equal or less drift than the internal one.
A Fluke 721A is not sufficient.
LM399H is minimum requirement, better another LTZ1000 or oven stabilized SZA263 (Fluke 732, 5440, 5720, 7000 etc.) reference is required.
Also a high quality short is required, either good laboratory cables, or a clean copper wire.

If the instrument is not rock stable under the described conditions, it would be faulty.

How long the Geller ref takes to stabilize, I cannot tell. But weeks would be too long, to give a reliable reading,  I think.

Frank

[ManateeMafia]

I should have been more specific. I was referring to service note 3458A-18A, where the reference may revert back to its pre-aged state if left off for extended periods.

http://literature.agilent.com/litweb/pdf/3458A-18A.pdf

The meter that I repaired came to me as a "for parts only" deal along with a second unit in much worse shape. I was able to piece together one good one out of two, but they sat for about 9 months in my possession before I  worked on them. I went through the calibration procedure using a 10V reference and 10K resistor since the NVRAMs were replaced.

I compared the fixed meter to a third that sat for about 6 months. There was a difference between the two meters. There possibly may be an unknown issue with the repaired meter, but it seemed to drift from zero a lot farther in the beginning and now it is pretty steady day to day. I leave it on 24/7 with the inputs shorted and have been patiently waiting to get a proper calibration from Agilent. I have a few other projects I am working on and my list of to-dos is getting longer.

Perhaps this service note does not apply, I am not certain, but I thought it may be at least somewhat relevant if it is unknown how long the meter sat before it was repaired.

[Dr. Frank]

I should have been more specific. I was referring to service note 3458A-18A, where the reference may revert back to its pre-aged state if left off for extended periods.

http://literature.agilent.com/litweb/pdf/3458A-18A.pdf

The meter that I repaired came to me as a "for parts only" deal along with a second unit in much worse shape. I was able to piece together one good one out of two, but they sat for about 9 months in my possession before I  worked on them. I went through the calibration procedure using a 10V reference and 10K resistor since the NVRAMs were replaced.

I compared the fixed meter to a third that sat for about 6 months. There was a difference between the two meters. There possibly may be an unknown issue with the repaired meter, but it seemed to drift from zero a lot farther in the beginning and now it is pretty steady day to day. I leave it on 24/7 with the inputs shorted and have been patiently waiting to get a proper calibration from Agilent. I have a few other projects I am working on and my list of to-dos is getting longer.

Perhaps this service note does not apply, I am not certain, but I thought it may be at least somewhat relevant if it is unknown how long the meter sat before it was repaired.

Service note 18A describes faulty references in agilent instruments (serial number beginning with "US....."), produced  just before 2007. You should find out very easily from instrument serial numbers, or PCB date codes, if that applies to your repaired instrument, or its diverse assemblies.

I don't know, which parameter you have compared against the other working 3458A, as your description is rather vague again.

As I already stated:

If zero reading and Full Scale reading against a known good reference are not rock stable after 4h warming up under stable environmental conditions, your repaired instrument still is faulty, quite obviously.

Frank

[TiN]

Congratz.

I see MV106 quite popular, lol That's all because Dave videos. 

[eurofox]

Hi Volt Nuts,

I got finally my voltage reference from Geller Lab and could calibrate the unit. I’m very happy with it. 
After final calibration when I measure the reference I get from 9,999999 to 10,000001 VDC. 
It is not too bad I think, because it is calibrate with the same reference it is what I can expect if the instrument is working well. 

I just have the keyboard to fix, I did not open it but due to the nature of the key’s I expect that it is a system like in the TV remote control where carbon is used and make a short on the PCB.

I order some repair kit with carbon.

If someone got experience with this kind of problem advice and comments are welcome.

eurofox

[Dr. Frank]

Hi Volt Nuts,

I got finally my voltage reference from Geller Lab and could calibrate the unit. I’m very happy with it. 
After final calibration when I measure the reference I get from 9,999999 to 10,000001 VDC. 
It is not too bad I think, because it is calibrate with the same reference it is what I can expect if the instrument is working well. 

If someone got experience with this kind of problem advice and comments are welcome.

eurofox

Instead of 7 1/2 Digits, you should arrange the 3458A to display/measure 8 1/2 Digits, i.e. NDIG 8, NPLC 100, and then report the stability of the Geller ref .
A good ref should be stable to a few parts on the very last digit.

Anyhow, congrats again, and have fun.

I think, the front including keypad is available as spare part from agilent, and does not cost that much.

But first inspect, if that is really the problem, perhaps a cleaning of keys and PCB is sufficinet, if a liquid had been poured over.

Frank

[eurofox]

Hello Volt Nuts,

Update of repair of my HP3458A

I got the carbon glue yesterday, in fact I order "Keypad fix" and "Wire glue" and they are both very similar, produced by the same company.

I did some test on paper and gummy and test the flatness and the resistance, I’m very surprised that this stuff is conducting very well.
Finally I decided to use the “Wire glue” and it is anyway indicated that it can be used to repair gummy keys like keys from a remote control as well.

After removing the front panel (tricky) and opening the keyboard, cleaning all keys on both side the PCB and the gummy part I add a very thin coating of carbon glue on all keys not only the few “bad” keys.

All keys are working now perfectly. 

I add extra RAM for option 1. 

The instrument is working well now without errors anymore. 

I have decided to send it to Agilent to calibrate it correctly, DC and resistance is ok after calibration with a DC reference and a 10k resistor but AC is not really accurate anymore compared to my 6 ½ digits that is calibrated.

This ways I will have a rock solid AC/DC/Resistor reference in my lab because of the age of the instrument it will not drift much anymore.

On ebay the prices are getting up all the time from US$3000 to more than US$6000, it is a good investment

I’m working on a 10V DC reference based on the LTZ1000A, I’m just curious to compare it to the Geller Lab module.

eurofox

[rjyousey]

We have a nice 3458a for $3850 usd with opt 001 and 002, it was recently checked by a high end cal and repair lab, sold and returned because with a blown current fuse.  We have since replaced the fuse and retested the unit.  908-328-3663

[eurofox]

My 3458A is on he's way for calibration in Agilent lab.

I'm curious to check the Geller Lab reference compared to the new calibration.

I will be able to check and correct my own calibration tools 

eurofox

[texaspyro]

A local contract assembly house was shutting down their operations and yesterday there was a liquidation auction.  One lot was a new-ish Agilent 3458A (option 002) that has been kept under a maintenance contract.   It passed self-tests and ACAL.   I had a nice talk with their lead tech and he gave me the history.  $2000 later and it's mine (I didn't really need a fourth one, so I low-bid it... will wonders never cease).  I also got a HP-58503B GPSDO.

They also had a second 3458A in a lot of 50 pieces of test equipment in their "to-be-repaired / calibrated" cage.   It had a sticker on it "Do not use, readings inaccurate". I bid $500 on the lot, but it went for $1500.  There was a lot of nice stuff in that lot (and some crap)... I should have bid more.  I had a guy lined up who was willing to load and remove all the equipment in exchange for anything I did not want to keep.