HP 3458A check out when you're looking at one? - Page 1
Forum section: electronics / general

author: notfaded1
author_rank: Frequent Contributor
timestamp: February 07, 2020, 09:34:16 pm
content: I'm finally getting an opportunity to aquire a 3458. I found it in state by another method than the auction network and I'm going to drive 200 miles one way to get it tomorrow. I know the basic self test it runs and have watched TiN's live stream where he's checking out some of his. Besides the basic self test that's fairly good at showing glaring problems is there anything else you would check out since I'll be able to turn it on and can take some things with me to check it out in person. I was going to take my Datel portable voltage standard with me to see if it's ballpark around 10V range. Perhaps take one of my decade resistance standards to check that too. I'm excited to finally get a 3458A and something better than my current 34401A. I'll feel better seeing it work and then not have to have it shipped too since I'm driving it.Is there any other easy things I should check?Thanks,Bill

author: valley001
author_rank: Frequent Contributor
timestamp: February 08, 2020, 02:04:12 am
content: #1- I am jealous#2- I would like to know this information as well.

author: syau
author_rank: Frequent Contributor
timestamp: February 08, 2020, 03:27:31 am
content: Please also test the jack at the back plate as people tends to miss itIf the unit passed self test and all measurement spot on then I don’t think you can do much as the service note 18A required weeks or months of testing for the famous drift in U180.

author: martinr33
author_rank: Frequent Contributor
timestamp: February 08, 2020, 03:42:21 am
content: Short the inputs with a copper wire (U shape) and put it on 100 NPLC / 10V range / NDIG 9. The last digit should be stable, single digit moves around the zero.If the unit has a drifty ADC, you are in for $800 - $1400 depending on what Keysight has in stock.If the unit has changed hands many times, your risk of a bad ADC is higher. Bad ADCs can appear in pretty much any unit, but maybe post-2008 are better.In any case, these units are expensive to get now, and you can live with the drift.

author: notfaded1
author_rank: Frequent Contributor
timestamp: February 08, 2020, 04:16:07 am
content: Thanks great point check the back inputs. I was also thinking short the input but great advice on settings because I'm not as familiar with these but am looking forward to joining the club. I've been waiting for this opportunity for so long... I guess you could say it's on my bucket list of voltnuterry and is really THE tool I wanted to find a way to but for a hobbiest it's a big bridge to cross.Thanks for everything you guys. I've learned more here than really anywhere when it comes to volts and time.Bill

author: TiN
author_rank: Super Contributor
timestamp: February 08, 2020, 05:55:10 am
content: I see buying 732A and High-end 10k resistance standard in your future....

author: niner_007
author_rank: Frequent Contributor
timestamp: February 08, 2020, 09:00:51 am
content: Quote from: notfaded1 on February 07, 2020, 09:34:16 pmthat was me on my first 3458A, now, 12 3458A later it’s different

author: ScoobyDoo
author_rank: Regular Contributor
timestamp: February 08, 2020, 09:32:50 am
content: Hello Bill - I would suggest you ask a 90 days return money back warranty in case the unit is not stable and you do not want to invest in new / refurbished boards to repair. If the seller is confident that his unit is trustworthy than I see no reason why he should refuse such request ...Good luck with your first unit !ScoobyDoo

author: Kleinstein
author_rank: Super Contributor
timestamp: February 08, 2020, 09:42:20 am
content: If one is lucky the last ACAL was done longer time ago. Than one could do a crude check for the dreaded ADC ASIC drift:Read out the CAL72 value and last ACAL date, do an ACAL and compare. There should not be too much drift in the CAL72 value.The test may not be 100% reliable if the meter was not used for longer time (possible reversible humidity effect).I don't know if this is possible via the keyboard or needs the remote interface.Anyway ACAL is a reasonable good extra self test and the amount of scattering could indicate possible, though not that likely problems.

author: HighVoltage
author_rank: Super Contributor
timestamp: February 08, 2020, 10:00:45 am
content: Quote from: niner_007 on February 08, 2020, 09:00:51 amYou still have all 12 instruments?For checking the instrument, take a stable 10k resistor with known value and compare.If you don't have one, may be you can borrow one.

author: MiDi
author_rank: Frequent Contributor
timestamp: February 08, 2020, 01:41:40 pm
content: Quote from: Kleinstein on February 08, 2020, 09:42:20 amFor ACAL it is unlikely that you get last Date, if not documented somewhere or owner could tell you.CAL72 (and all others) can be accessed from and viewed on Frontpanel.Recommend to note the last CAL175 too, it is the DCV cal temperature.The last CAL values are overwritten when doing new ACAL, so get the last values first.

author: notfaded1
author_rank: Frequent Contributor
timestamp: February 08, 2020, 07:17:52 pm
content: Thanks guys you helped me out 100% I couldn't have done this without your help and guidance!!! Attached is the money shot! The 3458 is sitting on his dad's lap. 😁👍😁👍😁Bill

author: notfaded1
author_rank: Frequent Contributor
timestamp: February 08, 2020, 07:23:52 pm
content: I'm so stoked I can't even put it into words... I even got the seller to throw in an HP33120A function arbretrary waveform generator!!! I bought it in Tuscon and drove down from Phoenix to get it. I felt much better driving it vs having him ship it.Nicest guy the seller too. He said he'll stand by all his gear. 🤗😁🤗😁🤗. He had a few antenna coming out of his house roof like old ham CB radio guy.Oh and I found out he bought all the gear in auction from defense industry company down there he used to work for. So I know all the history on this 3458. I'm basically the second owner and it comes from the original owner.Bill

author: Grandchuck
author_rank: Super Contributor
timestamp: February 08, 2020, 07:36:45 pm
content: Congratulations

author: notfaded1
author_rank: Frequent Contributor
timestamp: February 08, 2020, 08:14:29 pm
content: Quote from: niner_007 on February 08, 2020, 09:00:51 amYou have to be pro with 3458's now... I thought TiN had a LOT! Wow! One thing I was pretty sure about... This really isn't a great instrument to be buying a broken one without a lot of knowledge about them. The rusty one TiN fixed wow what a saga that was... I can only imagine that you've seen too.Bill

author: TiN
author_rank: Super Contributor
timestamp: February 08, 2020, 08:22:52 pm
content: Owning bunch of 3458s does not make one of a pro.It still takes lot of effort to find a golden 3458, like my two.

author: IanJ
author_rank: Unknown
timestamp: February 08, 2020, 08:31:37 pm
content: Quote from: notfaded1 on February 07, 2020, 09:34:16 pmCongrats on the 3458A......and welcome, chasing the least significant truly starts here.Ian.