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.
