Repair worklog : Old rusty HP 3458A

[crispy_tofu]

Congrats on the purchase!!

[Monittosan]

I think I'm going to have to get another 3458A after today 

[TiN]

Get your pocketses ready to be emptied

[VK5RC]

Thanks CrispyT, I am aware I am not in the league of TiN, Dr F and the others so I will do a lot of reading/testing before I do anything!
Starting from re reading this thread!

[TiN]

Fixing RAM is fairly easy. You can get more details from my worklog. Use solder sucker or wick to release original NVRAM pins and solder collet-type socket instead. You can try your luck with Maxim samples for DS1230 (U need two) and DS1220 (need one).

Save calrom by GPIB tool first, i can be lost any time on old unit.

[VK5RC]

Thanks TiN, I appreciate you being so helpful by putting all your work up on the web so others can travel the path so much more easily.
It will be a few days before I get my unit, so I am reading already!

[Monittosan]

Thanks TiN, I appreciate you being so helpful by putting all your work up on the web so others can travel the path so much more easily.
It will be a few days before I get my unit, so I am reading already!

I wish you lived in Melbourne I would of dropped it off to you

[deadlylover]

It will be a few days before I get my unit, so I am reading already!

Keysight in Australia charges around a grand for calibration, but I don't know what uncertainties they have. I *think* it was in the range of 3.6ppm or so, they use a golden 3458A in 90day cal as reference.

TRVMS in Sydney has a 10V standard (Statronics VS4 // 1.5ppm uncertainty 95%) and 10kOhm standard (good ol' ESI SR104 // 1ppm ditto) you can use for artefact calibration, was arouuuund 600 buckeroos. This doesn't include verification of all ranges and functions, it's the external cal only.

If you're a high roller, the NMI charges an arm, leg and a kidney. The base charge was 2 grand + a couple of hundred PER RANGE. This is with their JJA, it doesn't get much better than that.

But if it's just for hobbyist use, you can send me a voltage reference/resistor and I'll measure it for you on my R6581, it was calibrated at TRVMS in March, I'm good for ~7.5ppm on 10VDC and ~9ppm on 10KOhms. Probably much better than that but I won't know until the next cal.

[TiN]

Taiwan is just few seas away  O0

But I actually already have some work. Not sure if I should start other thread instead, or just post in here.

Nice and crispy:



Also blown cap:



What should I do with this? Plan was to use this part as donor for parts, but I think I can fix it... No custom unobtanium ASICs on it..



+18V rail is likely blown, with some (many?) other parts dead on it's way. C305 sits on +18VDC too.

P.S. No, my 3458A still OK, it's another A1 DC board   

[ManateeMafia]

I don't know about Oz, but Agilent was selling full service contracts for the 3458A as long as it was passing calibration. I was able to get a 5 year contract on mine regardless of its age. Few companies are willing to support equipment that old. The price, IIRC, was about $180/yr. I am not sure about current pricing or restrictions.

[TiN]

Wasn't that a deal only if you pay full $2.6K cal first?

[Macbeth]

TRVMS in Sydney has a 10V standard (Statronics VS4 // 1.5ppm uncertainty 95%) and 10kOhm standard (good ol' ESI SR104 // 1ppm ditto)

Doesn't somebody else in Sydney have a 10kOhm 0.1ppm standard? 

https://www.youtube.com/watch?v=UYGl0vebWN8&feature=youtu.be&t=2m24s

Dave has yet to make a voltnut vid using this. I guess he's waiting for a JJA to arrive in the mailbag 

[ManateeMafia]

I went with the standard (lowest price) calibration and they were willing to offer me a 3 or 4 year contract afterwards. I had to talk with someone else within the company that would agree to the 5 year. Not sure if the folks at Loveland were aware of all the contract options.

[deadlylover]

I went with the standard (lowest price) calibration and they were willing to offer me a 3 or 4 year contract afterwards.

Mate do you remember off hand what the uncertainty was for your 3458A @ 10VDC at time of calibration? I have no idea if it's included in the data for the standard cal. (which is a bloody shame considering what they're charging eh?)

Doesn't somebody else in Sydney have a 10kOhm 0.1ppm standard? 

That's a very nice transfer standard specced at 1ppm/yr. 

Ugh I need to get around to building a LTZ1000 based reference & ordering a bunch of resistors from Edwin, but the AUD is like monopoly money now... 

[ManateeMafia]

I will have to look it up later and see if it was spec'd. It is a shame and certainly a lower cost cal can be found elsewhere. The biggest benefit to me is if it goes in for cal and it fails, the same people repair it. I haven't researched if there is an additional cost for the second calibration but I would assume there would be a partial credit on the first, and full charge on the second. That should have been something I should have asked but didn't think of at the time.

[bingo600]

@TiN, MM and Dr F, I think you have a lot to answer for ! (HiHi)
I have just bought a 3458A that needs a little love (1 Fault = RAM Test Low) for a reasonable "Australian" price

Congrats & welcome to the '58 Club 

/Bingo

[ManateeMafia]

Congratulations and hopefully you will have minimal issues outside of replacing the nvram.

[VK5RC]

Thanks, the effort that a lot of the EEVblog contributers esp TiN , by not only doing the repair and showing pictures but also documenting the job give me a bit more confidence to 'have a go ya mug' HiHi.

[lowimpedance]

If you're a high roller, the NMI charges an arm, leg and a kidney. The base charge was 2 grand + a couple of hundred PER RANGE. This is with their JJA, it doesn't get much better than that.

Your soul will be required too 


To late to call the fire dept. then 

Nice and crispy:

[TiN]

Since somebody asked in other thread, here are few datalogs on ranges/ppm shorted input noise (using my short 4W PCB)

ACV (in SYNC mode, LFILTER ON):



OHMs (up to 1000 range, need rerun rest ranges). It is definately looks like out of wack..



Script for ohm readings (I'll run it later again, for all ranges)
EZGPIB Script for 3458A ohms.

[Dr. Frank]

Good idea to use DISP MSG command to output empty spaces, so you will not kill VFD too quick when running long data capture sessions. Only problem, bottom line like "SMPL", "MRNG" segments still lit. DISP OFF command disables them, but it outputs "-------" dashes on main line instead 



I'll be out of town this weekend, so meter will be left on, running this piece of code for 2 days.

Hello TiN,

It's no problem to blank the display completely including the annunciators, and without changing the firmware code.    I just tested that. 

Simply send "DISP OFF" plus a message text, that is a blank string inside two single quotation marks (!!), to the 3458A:  DISP OFF,'    '

Explanation - as always RTFM - in the user manual, chapter 6 - Command Reference, about "DISP", and the last line of the examples contains the crucial hint, p. 171/172 of the online pdf document!

You only may have to format these quotation marks correctly in your compiler, as these also were used for text string delimiters in many programming languages.
In Pascal the text string has to be formatted as:

     cmd:= 'DISP OFF,''    ''';

Frank

[TiN]

  Yea, it always helps to RTFM, sorry for dumb questions.

It's can be a very bad habit to go always most difficult way to do something simple..

I seem also to discover why my noise numbers on slow NPLCs are bad:

NPLC 50, 10VDC



NPLC 1000, 10VDC



There are these wierd steps, with period 20 minutes. I rechecked today, everything in room except PC is turned off.
Maybe it's refrigerator?

Eh.

[deadlylover]

Thanks TiN for testing the ACV for me. ^^

I really need to set up a computer in the lab so I can start logging data, maybe I can just use the math function to get STDEV on the R6581 as an appetiser...

In regards to DISP OFF giving you dashes, could be worse; 

[VK5RC]

My new 'baby' arrived, all intact form the travels. Clean on the outside, under a ~2009 calibration seal, the inside looks like someone had smoked near it, lots of really fine black dust esp near the fan, unfortunately that is also close to the voltage reference. It had a known NVRAM failure (replacements arriving soon I hope) but also showed an ACAL AC required warning, (photo1) on first ACAL ALL , showed a new ?downslope error fault ( didn't photograph) but thought all that smoke wouldn't be good. After 2-3hours of cleaning with static protection, and re do ACAL AC it has resolved. Still need new NVRAM.

What programs do you guys use to 'talk' to your 3458, I have a Prologic GPIB-USB and Win XP PC? (PS I am not a good programmer!!!!!)
I want a good copy of the cal data before I change even the non CAL RAM.

[ManateeMafia]

Yes, dust is not uncommon. Some 3458A appear to live their lives in a dirty/dusty environment as I have seen similar crud in a few. Some of the Vishay resistors on the reference board look twisted, or it could be the angle of the photo.

I believe there were multiple scripts posted recently but I cannot remember if it was this thread or the 3245A thread.

You can download the utility from here ...  https://xdevs.com/article/hp3458a_gpib/#summary Scroll to the bottom of the page.

The 110 Error may indicate some or all cal data is corrupted but it couldn't hurt to back it up anyway as desoldering old NVRAM is pretty risky.