I would like to thank everyone that replied to my query on what to look for in my "new" HP-3458. I did find that the AUTO ZERO button does work fine, thanks to Bill's comments. I had looked in the manual, just not far enough.
The display is still perfectly readable but i would like it to be "perfect". I am particularly interested in the exchange display for $272 (better than $700 for a new one, as Todd suggested). Does someone have a contact number at Keysight that I could call (my experience is that one can spend a lot of time calling around until the right person is finally found). I certainly need to figure out how to copy and replace the NVRAM - I lost the calibration on my Datron 1082 by not realizing the memory backup battery died and now I need to calibrate it myself (the HP3458A should make that doable, I hope). Any suggestions would be greatly appreciated. I believe it has been covered before on Volt-Nuts and I need to go through the past discussions to find it. One question I have for the group is what should the display typically show with the input shorted? I see a reading of about -.0025 mV. That seems rather high. I tried several different banana cables (gold plated, tin plated) used to short the input terminals to see if thermocouple effects might be responsible but there was no change in the reading. Still learning. Thanks, Randy On Fri, Aug 15, 2014 at 8:06 AM, Jason Watson <[email protected]> wrote: > I've also seen excessive Guard to Low leakage when varistor RV501 has gone > bad (it's located on the front/rear switch pcb and it's possible to replace > it while leaving the circuit board in place if you are careful). > HP/Agilent/Keysight Part number is 0837-0196, cross referenced to a Harris > Corp. V430MA3A. > > > On Fri, Aug 15, 2014 at 10:46 AM, Stephen Grady <[email protected]> > wrote: > > > Randy, > > > > I have come across a few 3458A's that had leakage between Guard and Low > > when > > te guard is in external guard position. This was due to a leaky external > > guard switch and/or leaky front rear switch. This can be quickly > determined > > by measuring resistance between guard and low with guard external. This > > normally in not an issue except when you are using 3458A to measure > voltage > > with low above earth potential say in a bridge the guard low leakage will > > be > > loading other arm of the bridge. > > > > Kind Regards, > > > > Steve Grady > > Sydney, Australia > > > > -----Original Message----- > > From: [email protected] [mailto:[email protected]] On > > Behalf Of Randy Evans > > Sent: Friday, 15 August 2014 1:22 PM > > To: [email protected] > > Subject: [volt-nuts] New HP3458A > > > > I picked up a used HP3458A today, which I needed for some precision DC > > measurements i need to make. It passes all the self tests and the Auto > Cal > > but is there any thing else I can check ( I have a 14 day RR). It reads > a > > 10V standard I made within a few tens of ppm, but it's not a 732A but > that > > is at least comforting. It also reads an ESI 10Kohm standard resistor > dead > > on. > > > > The only problem is that the display has some faint pixels in some > > locations, with three in the second row for every digit location dead. > > Likely a pixel driver I would think. > > > > I am not too familiar with it yet but I noticed when I push the auto > zero > > button, the display has a blinking square until I hit a measurement mode > > button; e.g., DCV, ACV, OHM, etc. Is this normal? > > > > Regards, > > > > Randy Evans > > _______________________________________________ > > volt-nuts mailing list -- [email protected] To unsubscribe, go to > > https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts > > and follow the instructions there. > > > > > > --- > > This email is free from viruses and malware because avast! Antivirus > > protection is active. > > http://www.avast.com > > > > _______________________________________________ > > volt-nuts mailing list -- [email protected] > > To unsubscribe, go to > > https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts > > and follow the instructions there. > > > _______________________________________________ > volt-nuts mailing list -- [email protected] > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts > and follow the instructions there. > _______________________________________________ volt-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
