When I try to execute a 10V cal, I get an error code "209 HARDWARE FAILURE - - INTERNAL OVERLOAD:31" I suspect that the unit has a different security code than 3458. I can't change it without opening up the unit, which I don't want to do unless I decide to keep it. Do you have any other suggestions on how to check the A9 card?
On Sat, Nov 18, 2017 at 11:17 AM, Randy Evans <randyevans2...@gmail.com> wrote: > Illya, > > That is a great idea. I will give it a try. > > Thanks > > On Sat, Nov 18, 2017 at 4:47 AM, Illya Tsemenko <il...@xdevs.com> wrote: > >> Since you have 732A, testing should be easy enough. Calibrate faulty >> meter for zero and DCV 10V to 732A, record CAL? 2,1 value. This is your LTZ >> output. Then leave it running for few days to drift away and calibrate >> again to same 732A. Check CAL? 2,1 again. Calculate the difference and if >> it matches output drift (that 1.1ppm/day you mention) - you can be 80% sure >> that A9 is a problem. Other 19% go to A1 and A3 circuits, as 7V is not used >> directly in the meter, and there are still gain parts to get +12 and >> -12VREF on A3 and 10Vish bipolar levels on A1. If your CAL? 2,1 stays same >> (within 0.3ppm) then A9 is fine. >> >> >> On November 18, 2017 12:59:53 PM GMT+08:00, Randy Evans < >> randyevans2...@gmail.com> wrote: >>> >>> I just received an Agilent 3458A that has a problem with noise and a >>> drifting voltage measurements. I am using two Fluke 732As to compare >>> absolute voltage measurements over time against the Agilent and an HP >>> 3458A. The HP unit has a new A3 ADC card and seems to be very stable and >>> low noise, so is being used for comparison. I have been doing simultaneous >>> absolute voltage measurements and DC Cal Constant measurements several >>> times a day and then calculating the drift rates of the two units using the >>> HP Service Note 18 procedure. >>> >>> >>> >>> The results indicate the Cal Constant drift rate of both units is very >>> similar and within spec per Service Note 18. However, the absolute value >>> measurements show the Agilent unit changing 1.1 ppm over a day whereas the >>> HP unit is within a tenth of a ppm over a day. In my way of thinking the >>> Cal Constant procedure assumes the voltage reference board in the 3458A is >>> stable, hence the absolute value reading should remain essentially constant >>> after each ACAL DCV, which is the case with the HP unit. Since the Agilent >>> unit shows a steady drift in the absolute reading, this would indicate to >>> me that the voltage reference board is likely the cause of the problem, and >>> is also likely the cause of the noisy readings. If so, this is a >>> “relatively” easy fix (I have several 3458A voltage reference boards, one >>> of which has been continuously powered up for several years). >>> >>> >>> >>> The issue is that I have to make a decision to keep or return the Agilent. >>> It has a cal seal on it and if I open the unit up to change the voltage >>> reference board, I own it and can’t return it. I would appreciate an >>> opinion from the members of the group as to what they think the odds are >>> that the voltage reference board is the source of the problems with the >>> Agilent 3458A. >>> >>> >>> >>> Thanks, >>> >>> >>> >>> Randy Evans >>> >>> > _______________________________________________ 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.