A new addition to the lair... - Page 1
Forum section: electronics / general

author: slateraptor
author_rank: Frequent Contributor
timestamp: February 09, 2012, 07:43:09 am
content: Forgot to ask the assets manager to run a records check on which lab the DMM came from before leaving the warehouse; should get a response by sometime tomorrow. Needless to say, the meter is in absolute pristine condition and I'm still stoked that I've managed to land 4-wire capability without having to make a trip to the university lab at such a cheap price...acquiring Kelvin probes and a solid pair of unshrouded probes is another story though. Auction photo and after clean up pics attached below.EDIT: 1 set each of Probe Master8044Sand8018Sto compliment the new bench DMM...good enough for government.

author: saturation
author_rank: Super Contributor
timestamp: February 09, 2012, 01:03:04 pm
content: Congratulations! Just beware that series uses a 10 year Li backup battery to store calibration data; when it goes so does the cal. You may want to serious consider replacing it before it goes.

author: slateraptor
author_rank: Frequent Contributor
timestamp: February 09, 2012, 01:53:34 pm
content: Thanks for the heads up. I recall reading about that battery for retaining calibration data in the operator's manual but didn't think twice about it.

author: robrenz
author_rank: Super Contributor
timestamp: February 09, 2012, 02:04:46 pm
content: I made my own set of Kelvin leads with a simple current reversal switch to eliminate thermal EMF'shttps://www.eevblog.com/forum/blog-specific/gaussian-resistors/msg71215/#msg71215clips are still available on ebay:http://www.ebay.com/sch/i.html?_nkw=mueller+kelvin+clips+&_cqr=true&_nkwusc=meuller+kelvin+clips&_rdc=1

author: ivan747
author_rank: Super Contributor
timestamp: February 10, 2012, 01:19:10 am
content: Quote from: saturation on February 09, 2012, 01:03:04 pmCan one replace a dying battery by connecting a relatively high impedance source in parallel and then swapping the old battery for a new one? I have always wondered about this, specially when the batteries power a RAM chip.

author: lowimpedance
author_rank: Super Contributor
timestamp: February 10, 2012, 02:23:47 am
content: Quote from: ivan747 on February 10, 2012, 01:19:10 amI have replaced a RAM backup battery in a HP8904a , according to their procedure you connect your external battery or PS through a 10k then replace the old internal RAM battery. Remove external connection, check all is still good and your done.

author: BravoV
author_rank: Super Contributor
timestamp: February 10, 2012, 03:23:15 am
content: Congratulation, looks like its still in a really nice condition.Quote from: slateraptor on February 09, 2012, 07:43:09 amLooks like those probe's banana jacks are shrouded, you might need to cut those plastic shroud.At mine, I love to use the banana to bnc binding post like this here ->ClickQuote from: saturation on February 09, 2012, 01:03:04 pmAs above saturation's concern, if you're going to replace that battery, please share and make a new thread for it, I might join you as well replacing mine, although last time I did measure it, the batt's voltage still fine.

author: bfritz
author_rank: Regular Contributor
timestamp: February 10, 2012, 04:43:28 am
content: Good meter, you're going to be a happy man!My favorite leads are Pomona 6235. The tips have a slight bend, and are very sharp, excellent for probing surface mount devices.http://media.digikey.com/photos/Pomona%20Photos/6235.JPGThe 6235 set comes with one red, one black, and a set of clear rubbery covers for the tips when not in use. Without the rubber tips, you will draw blood regularly! LOLEnjoy you new friend. I'm sure you will give him a good home, and treat him well.

author: BravoV
author_rank: Super Contributor
timestamp: February 10, 2012, 06:34:58 am
content: Here some infos to save your time in searching it in the service manual, its about the cmos ram backup battery that I've captured & stored while ago, its just don't have time to actually do it yet, fyi my battery is still at about 2.98 volt after all this years.Quotes from the HP3468A service manual :Hope this helps.

author: nukie
author_rank: Frequent Contributor
timestamp: February 10, 2012, 07:28:35 am
content: I wonder a Tadiran 3.6V battery is okay for a substitute.

author: slateraptor
author_rank: Frequent Contributor
timestamp: February 10, 2012, 11:15:37 am
content: Quote from: lowimpedance on February 10, 2012, 02:23:47 amUnfortunately, there doesn't appear to be any explicit procedure for this battery replacement in the service manual. Shouldn't be problematic though...and if I goof it, perhaps one of my PMEL buddies can bail me out. =PQuote from: BravoV on February 10, 2012, 03:23:15 amThe specific models purchased have retractable sheaths, which was something I was explicitly looking for; really helped to narrow down prospective candidates to a small sub-set from the ridiculous options on the market. When I get around to replacing the battery, I'll def do a write-up, maybe even a video.

author: Unknown
author_rank: Unknown
timestamp: February 10, 2012, 10:54:04 pm
content: Quote from: slateraptor on February 09, 2012, 07:43:09 amNice catch. How much did it set you back?Quote from: BravoV on February 10, 2012, 06:34:58 amI believe the typical Li-(CF) batteries used for these applications have a very flat discharge curve, until they're fully depleted, then the voltage suddenly collapses. So cell voltage may not be a very reliable indicator of charge.

author: slateraptor
author_rank: Frequent Contributor
timestamp: February 10, 2012, 11:17:13 pm
content: Quote from: alm on February 10, 2012, 10:54:04 pmUS$83.60 after tax and buyer premium.

author: slateraptor
author_rank: Frequent Contributor
timestamp: February 22, 2012, 07:19:34 am
content: Just wanted to follow up and say that after a little over a week of extensive use, I've pretty much tossed the OE Fluke probes that came with my 87V out the window. The mini-grabber adapter is soooooooo useful.