Bill, I installed the U-short and executed the BLUE-C-0 front panel command and I get an ERR on the display. I assume this is not good. Did I do this correctly?
Thanks, Randy On Sun, Aug 17, 2014 at 10:49 AM, Bill Gold <wpgold3...@att.net> wrote: > Randy: > > Look at page #23 of the 3458A Calibration Manual. Make yourself a "4 > Terminal Short" as shown and put it in as shown. > > Before I did an ACAL I had around -000.00025 mVDC. After ACAL I now > read +000.00002 mVDC. I did the "CAL 0" myself so I would expect that the > meter should return to a low value, and it does. I do get a variation of > +/- 30 nVDC using 100 PLC and just observing the variations. As I remember > I have never seen a spec on the ZERO stability over temperature. > > If I turn on the MATH function and then do 40 measurements with 100 PLC > the statistics show: > > Low reading -70 nVDC > Mean reading -28 nVDC > High reading +3.5 nVDC > Total Variation 73 nVDC > > So that correlates with my visual observation of 60 nVDC. After an > hour > the room had gone up around 1 degree C. Then I observed -000.00023 mVDC. > After another ACAL the reading was again +000.00002 mVDC. This particular > meter has a negative tempco as the room temp goes up. > > Obviously do an ACAL before any precision measurements requiring low > nanovolts. > > Go to the Keysight website and go to "Technical Support" and choose > "Parts". Then enter in the "Part Number" "03458-66517" which is the > replacement "03458-66507" assembly and you will see the replacement part > number on the right hand side. Click on that and you will get the > information about the exchange program and so on. Looks like you can just > order this part online and pay for it with a credit card, but you have to > create or use an existing login account. > > I needed a new display a few years ago. At that time you could order > just the display for around $80. Being extremely good at removing and then > inserting and soldering I ordered the part. The problem was that the > spacing from top to bottom of the pins had changed. It went from around > 1.3 > inches to around 1.5 inches. So I had to bend the pins to fit my display > board and then get something like 72 pins into the holes on the PC Board. > It took hours. This change is probably why HP/Agilent/Keysight doesn't let > you just get the display anymore but wants you to get the whole PC Board > assembly. It did work just fine once installed. > > Hope this helps your decision to keep or not. > > Bill > > > > ----- Original Message ----- > From: "Randy Evans" <randyevans2...@gmail.com> > To: "Discussion of precise voltage measurement" <volt-nuts@febo.com> > Sent: Saturday, August 16, 2014 10:36 PM > Subject: Re: [volt-nuts] RE "new" 3458A > > > > Interesting note. After the room cooled down from about 79F to 73F, and > > another ACAL, the meter now reads +000.00035 mVDC, a more reasonable > value, > > although it does bounce around a couple of tenths of a uV. > > > > Maybe that is OK? If so, then the only issue would seem to be the > display > > has some faint pixels, which a new display should fix. > > > > Randy > > > > > > On Sat, Aug 16, 2014 at 9:59 PM, Randy Evans <randyevans2...@gmail.com> > > wrote: > > > > > > > > The unit seems to be working so far except for one issue. After doing > an > > > ACAL, and making sure the Auto Zero is ON, I short the input leads > with > a > > > copper wire shunt across the inputs and the reading is approximately > > > -000.0023 mVDC. That seems rather high. I would expect the unit to > short > > > the input leads internally and force a zero reading during the ACAL. > > > Anyone have any comments on this reading? > > > > > > Thanks, > > > > > > Randy > > > > > > > > > On Sat, Aug 16, 2014 at 3:37 PM, Richard Moore <richiem5...@gmail.com> > > > wrote: > > > > > >> Hi Randy -- sounds like your unit is in cal, based on your > measurements > > >> of DCV and precision 10k resistor. > > >> > > >> Using autocal all is recommended before doing precision measurements, > and > > >> I do that if it's been more than a day or two since last use. The > autocal > > >> uses the internal Vref and an internal 10K resistor to do cal on > everything > > >> else, so that tells you what the basic cal procedure is. I just got my > 3458 > > >> back from Loveland, and that's what they did for me -- warmed it up, > then > > >> ran autocal, then measured everything against a Fluke 5700, aided by > an > HP > > >> 3325, and another 3458. > > >> > > >> It has been 5 years since I replaced the display board (no "exchange" > > >> deal was available then AFAIK, so I don't know what's changed) and > also > the > > >> NVRAM board, which was dead, with one with the Snap-cap RAM chips. I > did > > >> those replacements, then sent it home for cal, which was complete, > since > > >> all the RAM was new. Now after 5 years, the unit passed all incoming > > >> performance tests and was sent back to me without a cal process of any > > >> kind. This tells me that an old, well-aged Vref module is a good > thing. > The > > >> 10VDC test had changed by a bit under 5ppm, or roughly 1ppm/year. > > >> > > >> They have a cal deal -- use code 1.090 -- press them for it -- and > that > > >> saved me 30% off the normal price. I think this deal lasts until > > >> mid-September, so my recent "cal" ended up at just under $400 > including > > >> shipping. I'm not sure the deal is available on new or first-time > cals; > my > > >> unit was in their data bank. > > >> > > >> But this is a long way of saying I don't think you need to send it for > > >> cal -- just push Auto Cal and Enter and wait about 10 minutes and you > > >> should be good to go. > > >> _______________________________________________ > > >> volt-nuts mailing list -- volt-nuts@febo.com > > >> To unsubscribe, go to https://www.febo.com/cgi-bin/ > > >> mailman/listinfo/volt-nuts > > >> and follow the instructions there. > > >> > > > > > > > > _______________________________________________ > > volt-nuts mailing list -- volt-nuts@febo.com > > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts > > and follow the instructions there. > > _______________________________________________ > volt-nuts mailing list -- volt-nuts@febo.com > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts > and follow the instructions there. > _______________________________________________ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
