Re: [volt-nuts] Agilent 3458A Issues
Thanks, I see whadt you were saying. On Nov 23, 2017 8:18 PM, "Illya Tsemenko" wrote: A3 ADC has no way to measure meter's reference drift, as all of the measurements are relative to A9 output and/or 40k STDR. In this respect ref output is taken as constant. As result drifty reference will cause all readings to drift as well after self-calibration, because DC constant is changed only after external DCV 10V cal. So you have either zero A9 drift assumed from ACAL DCV or zero drift ADC A3 assumed from CAL 10V. By playing with time you can narrow the more drifty component. Good stable 3458A stable to <0.2ppm over week. On November 24, 2017 9:32:30 AM GMT+08:00, Randy Evans < randyevans2...@gmail.com> wrote: > > Illya, > > Can you explain why you say " If ACAL DCV does not remove drift then A3 > is probably fine". I don't really follow the argument. > > Randy > > On Thu, Nov 23, 2017 at 5:18 PM, Illya Tsemenko wrote: > >> Well, one thing you can know for sure , that reference is indeed broken. >> Drift over a day should be way below the noise floor (<0.1ppm). With 1.7x >> gain of ADC scale that drift rate gives you around 0.8ppm +/- 0.3ppm due to >> zener noise. So it is in line of 1.1ppm/day. If ACAL DCV does not remove >> drift then A3 is probably fine. >> >> Since reference is much easier to troubleshoot and fix I would go with >> replacing LTZ chip and testing if drift go away, if that have any help on >> your desire to keep meter. >> >> Also serial number range in SN doesn't mean much for you, as meter >> history is unknown and it still may have been serviced at some time. >> >> On November 24, 2017 8:40:00 AM GMT+08:00, Randy Evans < >> randyevans2...@gmail.com> wrote: >>> >>> Illya, >>> >>> I ran the test you suggested over 4 days and got 7.19114068 VDC on the >>> start of the test and 7.19113736 VDC at the end of the fourth day (96 hours >>> later). I calculate a total of 0.46 ppm drift, which seems excessive but >>> does not account for the 1.1 ppm/day I measured overall. I suspect the A3 >>> card is the primary source of drifting. Since the unit is a late model >>> Agilent unit, that is well beyond the expected range of units described in >>> Service Note 18. What do you think? >>> >>> Thanks, >>> >>> Randy Evans >>> >>> On Sat, Nov 18, 2017 at 4:47 AM, Illya Tsemenko 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
Re: [volt-nuts] Agilent 3458A Issues
A3 ADC has no way to measure meter's reference drift, as all of the measurements are relative to A9 output and/or 40k STDR. In this respect ref output is taken as constant. As result drifty reference will cause all readings to drift as well after self-calibration, because DC constant is changed only after external DCV 10V cal. So you have either zero A9 drift assumed from ACAL DCV or zero drift ADC A3 assumed from CAL 10V. By playing with time you can narrow the more drifty component. Good stable 3458A stable to <0.2ppm over week. On November 24, 2017 9:32:30 AM GMT+08:00, Randy Evans wrote: >Illya, > >Can you explain why you say " If ACAL DCV does not remove drift then A3 >is >probably fine". I don't really follow the argument. > >Randy > >On Thu, Nov 23, 2017 at 5:18 PM, Illya Tsemenko >wrote: > >> Well, one thing you can know for sure , that reference is indeed >broken. >> Drift over a day should be way below the noise floor (<0.1ppm). With >1.7x >> gain of ADC scale that drift rate gives you around 0.8ppm +/- 0.3ppm >due to >> zener noise. So it is in line of 1.1ppm/day. If ACAL DCV does not >remove >> drift then A3 is probably fine. >> >> Since reference is much easier to troubleshoot and fix I would go >with >> replacing LTZ chip and testing if drift go away, if that have any >help on >> your desire to keep meter. >> >> Also serial number range in SN doesn't mean much for you, as meter >history >> is unknown and it still may have been serviced at some time. >> >> On November 24, 2017 8:40:00 AM GMT+08:00, Randy Evans < >> randyevans2...@gmail.com> wrote: >>> >>> Illya, >>> >>> I ran the test you suggested over 4 days and got 7.19114068 VDC on >the >>> start of the test and 7.19113736 VDC at the end of the fourth day >(96 hours >>> later). I calculate a total of 0.46 ppm drift, which seems >excessive but >>> does not account for the 1.1 ppm/day I measured overall. I suspect >the A3 >>> card is the primary source of drifting. Since the unit is a late >model >>> Agilent unit, that is well beyond the expected range of units >described in >>> Service Note 18. What do you think? >>> >>> Thanks, >>> >>> Randy Evans >>> >>> On Sat, Nov 18, 2017 at 4:47 AM, Illya Tsemenko >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
Re: [volt-nuts] Agilent 3458A Issues
Illya, Can you explain why you say " If ACAL DCV does not remove drift then A3 is probably fine". I don't really follow the argument. Randy On Thu, Nov 23, 2017 at 5:18 PM, Illya Tsemenko wrote: > Well, one thing you can know for sure , that reference is indeed broken. > Drift over a day should be way below the noise floor (<0.1ppm). With 1.7x > gain of ADC scale that drift rate gives you around 0.8ppm +/- 0.3ppm due to > zener noise. So it is in line of 1.1ppm/day. If ACAL DCV does not remove > drift then A3 is probably fine. > > Since reference is much easier to troubleshoot and fix I would go with > replacing LTZ chip and testing if drift go away, if that have any help on > your desire to keep meter. > > Also serial number range in SN doesn't mean much for you, as meter history > is unknown and it still may have been serviced at some time. > > On November 24, 2017 8:40:00 AM GMT+08:00, Randy Evans < > randyevans2...@gmail.com> wrote: >> >> Illya, >> >> I ran the test you suggested over 4 days and got 7.19114068 VDC on the >> start of the test and 7.19113736 VDC at the end of the fourth day (96 hours >> later). I calculate a total of 0.46 ppm drift, which seems excessive but >> does not account for the 1.1 ppm/day I measured overall. I suspect the A3 >> card is the primary source of drifting. Since the unit is a late model >> Agilent unit, that is well beyond the expected range of units described in >> Service Note 18. What do you think? >> >> Thanks, >> >> Randy Evans >> >> On Sat, Nov 18, 2017 at 4:47 AM, Illya Tsemenko 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.
Re: [volt-nuts] Agilent 3458A Issues
Well, one thing you can know for sure , that reference is indeed broken. Drift over a day should be way below the noise floor (<0.1ppm). With 1.7x gain of ADC scale that drift rate gives you around 0.8ppm +/- 0.3ppm due to zener noise. So it is in line of 1.1ppm/day. If ACAL DCV does not remove drift then A3 is probably fine. Since reference is much easier to troubleshoot and fix I would go with replacing LTZ chip and testing if drift go away, if that have any help on your desire to keep meter. Also serial number range in SN doesn't mean much for you, as meter history is unknown and it still may have been serviced at some time. On November 24, 2017 8:40:00 AM GMT+08:00, Randy Evans wrote: >Illya, > >I ran the test you suggested over 4 days and got 7.19114068 VDC on the >start of the test and 7.19113736 VDC at the end of the fourth day (96 >hours >later). I calculate a total of 0.46 ppm drift, which seems excessive >but >does not account for the 1.1 ppm/day I measured overall. I suspect the >A3 >card is the primary source of drifting. Since the unit is a late model >Agilent unit, that is well beyond the expected range of units described >in >Service Note 18. What do you think? > >Thanks, > >Randy Evans > >On Sat, Nov 18, 2017 at 4:47 AM, Illya Tsemenko >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.
Re: [volt-nuts] Agilent 3458A Issues
Illya, I ran the test you suggested over 4 days and got 7.19114068 VDC on the start of the test and 7.19113736 VDC at the end of the fourth day (96 hours later). I calculate a total of 0.46 ppm drift, which seems excessive but does not account for the 1.1 ppm/day I measured overall. I suspect the A3 card is the primary source of drifting. Since the unit is a late model Agilent unit, that is well beyond the expected range of units described in Service Note 18. What do you think? Thanks, Randy Evans On Sat, Nov 18, 2017 at 4:47 AM, Illya Tsemenko 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.
Re: [volt-nuts] Agilent 3458A Issues
Problem solved! As expected, operator error. When I did the CAL 0, I shorted the voltage and sense lines separately but did not short them together. This caused error 209, which caused the CAL 10V to fail since the zero was not done correctly. All is well now. Still learning. On Sat, Nov 18, 2017 at 12:58 PM, Randy Evans wrote: > 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 > 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 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.
Re: [volt-nuts] Agilent 3458A Issues
In message , Randy Evans writes: >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. The 3458 is quite elonquent, and will say so clearly if that is the problem. 209 means that the compiled in limit on one of all the many calibration values is out of range. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ 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.
Re: [volt-nuts] Agilent 3458A Issues
If you were able to run CAL 0 with the inputs shorted, then security is not an issue. After that, try CAL 10.xx whatever the value is. I think overload means the expected value is out of range. On Sat, Nov 18, 2017 at 3:58 PM, Randy Evans wrote: > 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 > 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 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. > ___ 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.
Re: [volt-nuts] Agilent 3458A Issues
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 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 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.
Re: [volt-nuts] Agilent 3458A Issues
Illya, That is a great idea. I will give it a try. Thanks On Sat, Nov 18, 2017 at 4:47 AM, Illya Tsemenko 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.
Re: [volt-nuts] Agilent 3458A Issues
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 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.
[volt-nuts] Agilent 3458A Issues
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 HP-3458A Calibration drift rate 2017-11-17A.xlsx Description: MS-Excel 2007 spreadsheet ___ 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.
