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.