Re: [volt-nuts] volt-nuts Digest, Vol 12, Issue 11
Hi, Marv -- RE my 3458 -- It was very clean externally, leading me to think it had been used in a test or lab environment, but it needed a display board and a ROM board, both of which I installed. Then it went to Loveland for calibration. That was last September. Because the ROM board was replaced, there was no "before" data to compare the cal to. It goes back to Loveland this September, and now there will be "before" and "after" data which will provide an estimate of drift in parameters. It is not an -02 high-stability option unit.
The ROM board change essentially made this a good-as-new unit, at least according to Loveland -- it passed all pre-cal tests with flying colors and cal'ed without problems.
I believe that Loveland uses a Fluke 572x calibration system, which for DC is at least as good as the 732B. As to AC -- well I think it probably is as good as there is right now for cal use outside of labs. The specs for the 3458 reflect the uncertainty of the calibration standards, and the AC specs definitely show that. I bought that 3458 for $1600 on fleabay -- didn't want to pay too much more because of the ROM battery problems on older units with the Dallas ROMs that had built-in battery back up. The new ROM board has ROMs that have a snap-on battery which is apparently easy to replace, though I wonder how long they will be available via Agilent....
In any case, the display board was $400+, the ROM board was $500+ and the cal was about $500, so my total investment to this point is around $3100 -- a lot, but worth it. I just trust the 3458 without wondering if it is right. It is the only high-res measurer in the shop now, so it is right by definition. As Steve Rooke likes to say, "A man with one clock knows what time it is. A man with two clocks isn't ever sure."
Best,
Dick Moore
On Aug 25, 2010, at 5:00 AM, volt-nuts-request@febo.com wrote:
Message: 1
Date: Tue, 24 Aug 2010 19:52:37 -0400
From: "Marvin E. Gozum" marvin.gozum@jefferson.edu
Subject: Re: [volt-nuts] Back to voltage
To: Discussion of precise voltage measurement volt-nuts@febo.com,
volt-nuts@febo.com
Message-ID: 6.2.5.6.2.20100824183805.0504e360@jefferson.edu
Content-Type: text/plain; charset="us-ascii"; format=flowed
Hello Dick,
Thanks for your input. Your posts on time-nuts have been invaluable
as was the thread here and all its contributors:
http://www.mail-archive.com/time-nuts@febo.com/msg16497.html
The last I read on time and volt nuts, your HP 3458a had it share of
trouble, but you describe here its working true now, did it take much
to get back into factory shape?
Hi Dick,
Something in your post caught my eye. Are you aware that, although performed at Loveland, Agilent's $500 cal is not performed in their Standards Laboratory. In order to receive their Standards Lab Cal, you have to specifically ask for that, and the cost is approximately $1350.
Basically their $500 cal is a STE9000 "Service Center" cal, although it's now performed geographically at Loveland. I'm the one who calculated the STE9000 version MU approximately 20 years ago. ...And I tweaked the procedure a bit for a little better metrology. The STE9000 version calibration for 3458A was developed for field calibration, hence its inferiority to the Standards Lab cal.
Having intimately evaluated the two versions of 3458A cal, I would briefly summarize the situation as follows:
If you only need a "go / no go" status for your 3458A, then the STE9000 cal might be sufficient for you. But if you wish to actually use the supplied test data (that's supplied along with the calibration), then the STE9000 cal is insufficient and you instead want the Standards Lab cal.
Put another way, if you just want to depend on your 3458A performing within its published specifications, then the STE9000 cal is probably sufficient. But if you want to track or trend your 3458A by parameter - or to use its calibration test data as correction constants in your processes - then you must have the Standards Lab cal. (The MU of the STE9000 procedure is too high for the supplied test data to be of much value for those purposes.)
Knowing what I know, I'd rather send my 3458A for Standards Lab cal on a 3 year cal interval, instead of a one year cycle for STE9000 cal.
...apology if you already know this information... ...Just putting out the info in case otherwise. I do know, in the past, confusion over this issue has "tricked" many customers into ordering the wrong 3458A cal based on a misunderstanding of what version calibration they're receiving.
Best,
Greg
----- Original Message -----
From: "Dick Moore" richiem@hughes.net
To: volt-nuts@febo.com
Sent: Wednesday, August 25, 2010 1:26 PM
Subject: Re: [volt-nuts] volt-nuts Digest, Vol 12, Issue 11
Hi, Marv -- RE my 3458 -- It was very clean externally, leading me to think it had been used in a test or lab environment, but it needed a display board and a ROM board, both of which I installed. Then it went to Loveland for calibration. That was last September. Because the ROM board was replaced, there was no "before" data to compare the cal to. It goes back to Loveland this September, and now there will be "before" and "after" data which will provide an estimate of drift in parameters. It is not an -02 high-stability option unit.
The ROM board change essentially made this a good-as-new unit, at least according to Loveland -- it passed all pre-cal tests with flying colors and cal'ed without problems.
I believe that Loveland uses a Fluke 572x calibration system, which for DC is at least as good as the 732B. As to AC -- well I think it probably is as good as there is right now for cal use outside of labs. The specs for the 3458 reflect the uncertainty of the calibration standards, and the AC specs definitely show that. I bought that 3458 for $1600 on fleabay -- didn't want to pay too much more because of the ROM battery problems on older units with the Dallas ROMs that had built-in battery back up. The new ROM board has ROMs that have a snap-on battery which is apparently easy to replace, though I wonder how long they will be available via Agilent....
In any case, the display board was $400+, the ROM board was $500+ and the cal was about $500, so my total investment to this point is around $3100 -- a lot, but worth it. I just trust the 3458 without wondering if it is right. It is the only high-res measurer in the shop now, so it is right by definition. As Steve Rooke likes to say, "A man with one clock knows what time it is. A man with two clocks isn't ever sure."
Best,
Dick Moore
Hello Dick,
Thanks for sharing your insights. It is extremely helpful.
I fear the exact same fate for myself, in that I anticipate any
'working' eBay 3458a sold 'as is' that is not tested by a competent
vendor or calibrated by the seller to some spec, or moreso NIST
traceable, will be bound for some expensive repairs in the near
future, after purchase. The going rate for working meters is
$5k. Thereafter, there isn't much DIY I can forsee I may be able to
do myself that can keep the 3458a factory accurate, so professional
metcal costs should be factored in unless the meter starts to
'settled' in and stabilize.
At 03:26 PM 8/25/2010, Dick Moore wrote:
Hi, Marv -- RE my 3458 -- It was very clean externally, leading me
to think it had been used in a test or lab environment, but it
needed a display board and a ROM board, both of which I installed.
Then it went to Loveland for calibration. That was last September.
Because the ROM board was replaced, there was no "before" data to
compare the cal to. It goes back to Loveland this September, and now
there will be "before" and "after" data which will provide an
estimate of drift in parameters. It is not an -02 high-stability option unit.
Great! If you don't mind sharing the results of this cal results, it
would be much appreciated. Theoretically, an aged 3458a should start
to approach the stability of the high stability board but without the
factory blessing and testing, but one can't tell unless the cal
numbers come rolling in over time.
The ROM board change essentially made this a good-as-new unit, at
least according to Loveland -- it passed all pre-cal tests with
flying colors and cal'ed without problems.
I believe that Loveland uses a Fluke 572x calibration system, which
for DC is at least as good as the 732B. As to AC -- well I think it
probably is as good as there is right now for cal use outside of
labs. The specs for the 3458 reflect the uncertainty of the
calibration standards, and the AC specs definitely show that. I
bought that 3458 for $1600 on fleabay -- didn't want to pay too much
more because of the ROM battery problems on older units with the
Dallas ROMs that had built-in battery back up. The new ROM board has
ROMs that have a snap-on battery which is apparently easy to
replace, though I wonder how long they will be available via Agilent....
I read of those battery ROMs issues, even more maintenance costs. Is
there an anticipated replacement interval or a system test to
determine its remaining life? Are they specialized batteries that
cannot be substituted? are they costly?
In any case, the display board was $400+, the ROM board was $500+
and the cal was about $500, so my total investment to this point is
around $3100 -- a lot, but worth it. I just trust the 3458 without
wondering if it is right. It is the only high-res measurer in the
shop now, so it is right by definition. As Steve Rooke likes to say,
"A man with one clock knows what time it is. A man with two clocks
isn't ever sure."
Yes, a statistician would look at both clocks and know what it means ;)
I use the 3456a stat functions to reduce the uncertainty of the last
digit of measurement, and target as small a variance as
possible. Likewise, will multiple meters, you can compare the means,
and the variances. You may not have a rock solid number, but a
better handle of the uncertainty of the LSD of the scale.
Best,
Dick Moore
Sincerely,
Marv Gozum
Philadelphia, PA
Dick
I have read the exchanges on the subject of the HP3458A with considerable
interest. I purchased a working 3458A about a year ago from a source which
in turn had obtained it from a large Companies Lab. when it closed down. It
was in pretty good condition overall, but it has the ROM board with the
Dallas ROMs' fitted, and I await the day in trepidation when they "run
out", but I would prefer to replace the board as you have, with the later
type. As for calibration, mine was last cal'd by Agilent (here in the UK)
on 27/02/2007 with a next cal due date of 27/02 /2009. To date the
instrument has performed faultlessly. I anticipate that to replace the ROM
board with one obtained from Agilent UK would be very expensive, judging
from prices for other HP equipment replacement/repair prices. As you may
know, we in the UK usually pay the same amount in UK pounds that you in the
US pay in dollars. Has anyone in the UK purchased this item ?
Best regards.
Roy
From: "Dick Moore" richiem@hughes.net
Sent: Wednesday, August 25, 2010 8:26 PM
To: volt-nuts@febo.com
Subject: Re: [volt-nuts] volt-nuts Digest, Vol 12, Issue 11
Hi, Marv -- RE my 3458 -- It was very clean externally, leading me to
think it had been used in a test or lab environment, but it needed a
display board and a ROM board, both of which I installed. Then it went to
Loveland for calibration. That was last September. Because the ROM board
was replaced, there was no "before" data to compare the cal to. It goes
back to Loveland this September, and now there will be "before" and
"after" data which will provide an estimate of drift in parameters. It is
not an -02 high-stability option unit.
The ROM board change essentially made this a good-as-new unit, at least
according to Loveland -- it passed all pre-cal tests with flying colors
and cal'ed without problems.
I believe that Loveland uses a Fluke 572x calibration system, which for DC
is at least as good as the 732B. As to AC -- well I think it probably is
as good as there is right now for cal use outside of labs. The specs for
the 3458 reflect the uncertainty of the calibration standards, and the AC
specs definitely show that. I bought that 3458 for $1600 on fleabay --
didn't want to pay too much more because of the ROM battery problems on
older units with the Dallas ROMs that had built-in battery back up. The
new ROM board has ROMs that have a snap-on battery which is apparently
easy to replace, though I wonder how long they will be available via
Agilent....
In any case, the display board was $400+, the ROM board was $500+ and the
cal was about $500, so my total investment to this point is around
$3100 -- a lot, but worth it. I just trust the 3458 without wondering if
it is right. It is the only high-res measurer in the shop now, so it is
right by definition. As Steve Rooke likes to say, "A man with one clock
knows what time it is. A man with two clocks isn't ever sure."
Best,
Dick Moore
On Aug 25, 2010, at 5:00 AM, volt-nuts-request@febo.com wrote:
Message: 1
Date: Tue, 24 Aug 2010 19:52:37 -0400
From: "Marvin E. Gozum" marvin.gozum@jefferson.edu
Subject: Re: [volt-nuts] Back to voltage
To: Discussion of precise voltage measurement volt-nuts@febo.com,
volt-nuts@febo.com
Message-ID: 6.2.5.6.2.20100824183805.0504e360@jefferson.edu
Content-Type: text/plain; charset="us-ascii"; format=flowed
Hello Dick,
Thanks for your input. Your posts on time-nuts have been invaluable
as was the thread here and all its contributors:
http://www.mail-archive.com/time-nuts@febo.com/msg16497.html
The last I read on time and volt nuts, your HP 3458a had it share of
trouble, but you describe here its working true now, did it take much
to get back into factory shape?
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.
In message 949887D3866942A3857625622A0587AF@LapTop, "Roy Phillips" writes:
I found a HP3458A (on ebay for EUR1390) which had appearantly spent
its entire life with a german manufacturer of electromechanical
relays.
The only problem were a dead bit in the GPIB port, and a fresh
driver-chip solved that.
To say the CMOS RAMS were old would qualify for understatement of
the year award: They were 5 year models (Suffix Y) datecoded in '89.
I used the "MREAD" GPIB command to make a backup copy of the CALRAM
chip to my computer, before unsoldering all three CMOSRams and
mounting new ones (in sockets).
Afterwards I checked the old CMOSRAM's battery state, by measuring
the voltage over the GND and VCC pins in 10GOhm input mode and
found a healty 2.9something volts.
This is a point I think many of us overlook:
If the meter has been turned on 24/7, the lithium cell does not do
anything but sit there, and the reverse current of the diode that
separates it from the chip is often enough to keep the battery in
fine shape, despite the fact that it is not in any way shape or
form intended to be rechargeable.
And I think it is pretty safe bet that most HP3458A's are left powered
24/7, because that avoids the entire issue of warm-up etc.
But yes, eventually you will run out of battery, but it was probably
the easiest chip I have ever unsoldered: the holes were suprisingly
large.
So I would recommend you make a backup of the CALRAM with the MREAD
command (I described how to in a post some time back) and let your
batteries run out.
If like me, you keep the meter powered, it may never happen.
Poul-Henning
--
Poul-Henning Kamp | UNIX since Zilog Zeus 3.20
phk@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.
Dick,
How were you able to order the replacement A5 (outguard controller) board? From Agilent's website, it does not appear that I can order the original through-hole (03458-66505), the SMT (03458-66547) or the upgrade kit (03458-80047).
My cal NVRAMs are past their expiration date (but still working) and I've been reluctant to replace them. My main concern is that I won't be able to remove the NVRAMs intact enough to read their contents and program into replacements (which I would put into sockets). My go-to technique for replacing DIP packages usually involves a wire cutter. :)
Randy.
--- On Thu, 8/26/10, Roy Phillips phill.r1@btinternet.com wrote:
From: Roy Phillips phill.r1@btinternet.com
Subject: Re: [volt-nuts] volt-nuts Digest, Vol 12, Issue 11
To: "Discussion of precise voltage measurement" volt-nuts@febo.com
Date: Thursday, August 26, 2010, 9:32 AM
Dick
I have read the exchanges on the subject of the HP3458A
with considerable interest. I purchased a working
3458A about a year ago from a source which in turn had
obtained it from a large Companies Lab. when it closed
down. It was in pretty good condition overall, but it
has the ROM board with the Dallas ROMs' fitted, and I
await the day in trepidation when they "run out", but I
would prefer to replace the board as you have, with the
later type. As for calibration, mine was last cal'd by
Agilent (here in the UK) on 27/02/2007 with a next cal due
date of 27/02 /2009. To date the instrument has performed
faultlessly. I anticipate that to replace the ROM board with
one obtained from Agilent UK would be very expensive,
judging from prices for other HP equipment
replacement/repair prices. As you may know, we in the UK
usually pay the same amount in UK pounds that you in the US
pay in dollars. Has anyone in the UK purchased this item ?
Best regards.
Roy
From: "Dick Moore" richiem@hughes.net
Sent: Wednesday, August 25, 2010 8:26 PM
To: volt-nuts@febo.com
Subject: Re: [volt-nuts] volt-nuts Digest, Vol 12, Issue
11
Hi, Marv -- RE my 3458 -- It was very clean
externally, leading me to think it had been used in a test
or lab environment, but it needed a display board and a ROM
board, both of which I installed. Then it went to Loveland
for calibration. That was last September. Because the ROM
board was replaced, there was no "before" data to compare
the cal to. It goes back to Loveland this September, and now
there will be "before" and "after" data which will provide
an estimate of drift in parameters. It is not an -02
high-stability option unit.
The ROM board change essentially made this a
good-as-new unit, at least according to Loveland -- it
passed all pre-cal tests with flying colors and cal'ed
without problems.
I believe that Loveland uses a Fluke 572x calibration
system, which for DC is at least as good as the 732B. As to
AC -- well I think it probably is as good as there is right
now for cal use outside of labs. The specs for the 3458
reflect the uncertainty of the calibration standards, and
the AC specs definitely show that. I bought that 3458 for
$1600 on fleabay -- didn't want to pay too much more
because of the ROM battery problems on older units with the
Dallas ROMs that had built-in battery back up. The new ROM
board has ROMs that have a snap-on battery which is
apparently easy to replace, though I wonder how long they
will be available via Agilent....
In any case, the display board was $400+, the ROM
board was $500+ and the cal was about $500, so my total
investment to this point is around $3100 -- a lot, but worth
it. I just trust the 3458 without wondering if it is right.
It is the only high-res measurer in the shop now, so it is
right by definition. As Steve Rooke likes to say, "A man
with one clock knows what time it is. A man with two clocks
isn't ever sure."
wrote:
Message: 1
Date: Tue, 24 Aug 2010 19:52:37 -0400
From: "Marvin E. Gozum" marvin.gozum@jefferson.edu
Subject: Re: [volt-nuts] Back to voltage
To: Discussion of precise voltage measurement
volt-nuts@febo.com
Message-ID: 6.2.5.6.2.20100824183805.0504e360@jefferson.edu
Content-Type: text/plain; charset="us-ascii";
format=flowed
Hello Dick,
Thanks for your input. Your posts on
time-nuts have been invaluable
as was the thread here and all its contributors:
http://www.mail-archive.com/time-nuts@febo.com/msg16497.html
The last I read on time and volt nuts, your HP
3458a had it share of
trouble, but you describe here its working true
now, did it take much
to get back into factory shape?
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.
I've seen the subject of HP 4358 CMOS RAM come up umpteen times now.
Sadly, I do not own a 3458 myself and I do not know what exact type of
memory is used, but I've always wondered if it would be at all feasible to
use FRAM as a replacement. That would certainly put an end to all the
hassle and uncertainty of the battery back-up.
Just a thought.
Regards,
Rob.
Op 26-8-2010 17:25, Poul-Henning Kamp schreef:
In message949887D3866942A3857625622A0587AF@LapTop, "Roy Phillips" writes:
I found a HP3458A (on ebay for EUR1390) which had appearantly spent
its entire life with a german manufacturer of electromechanical
relays.
The only problem were a dead bit in the GPIB port, and a fresh
driver-chip solved that.
To say the CMOS RAMS were old would qualify for understatement of
the year award: They were 5 year models (Suffix Y) datecoded in '89.
I used the "MREAD" GPIB command to make a backup copy of the CALRAM
chip to my computer, before unsoldering all three CMOSRams and
mounting new ones (in sockets).
Afterwards I checked the old CMOSRAM's battery state, by measuring
the voltage over the GND and VCC pins in 10GOhm input mode and
found a healty 2.9something volts.
This is a point I think many of us overlook:
If the meter has been turned on 24/7, the lithium cell does not do
anything but sit there, and the reverse current of the diode that
separates it from the chip is often enough to keep the battery in
fine shape, despite the fact that it is not in any way shape or
form intended to be rechargeable.
And I think it is pretty safe bet that most HP3458A's are left powered
24/7, because that avoids the entire issue of warm-up etc.
But yes, eventually you will run out of battery, but it was probably
the easiest chip I have ever unsoldered: the holes were suprisingly
large.
So I would recommend you make a backup of the CALRAM with the MREAD
command (I described how to in a post some time back) and let your
batteries run out.
If like me, you keep the meter powered, it may never happen.
Poul-Henning
--
Small Design
Zuiddijk 354
1505 HD Zaandam
The Netherlands
tel. +31 (0)75 77 11 740
fax. +31 (0)75 77 11 742
e-mail: rob.klein@smalldesign.nl
Hi,
I also don't have a 3458A, but I do have experience with early battery backed up CMOS RAM. FRAM is an option. Can someone tell me the part number of the CMOS units currently used and I'll do a comparison. An other option that I've used before is external (to the module) back-up. Add a schoktty diode in series with the Vdd and use an external lithium (with an other diode) or rechargeable too keep the module powered. Or you can carry out surgery on the module and replace the cell. This problem is also common on video games and Sun SparcStations. See http://www.jmargolin.com/rdy2k/hdzram.htm and http://cmheong.tripod.com/work/mk48t02.html
Robert G8RPI
--- On Thu, 26/8/10, Rob Klein rob.klein@smalldesign.nl wrote:
From: Rob Klein rob.klein@smalldesign.nl
Subject: [volt-nuts] HP 3458A CMOS RAM
To: "Discussion of precise voltage measurement" volt-nuts@febo.com
Date: Thursday, 26 August, 2010, 17:55
I've seen the subject of HP 4358 CMOS RAM come up umpteen times now.
Sadly, I do not own a 3458 myself and I do not know what exact type of
memory is used, but I've always wondered if it would be at all feasible to
use FRAM as a replacement. That would certainly put an end to all the
hassle and uncertainty of the battery back-up.
Just a thought.
Regards,
Rob.
Op 26-8-2010 17:25, Poul-Henning Kamp schreef:
In message949887D3866942A3857625622A0587AF@LapTop, "Roy Phillips" writes:
I found a HP3458A (on ebay for EUR1390) which had appearantly spent
its entire life with a german manufacturer of electromechanical
relays.
The only problem were a dead bit in the GPIB port, and a fresh
driver-chip solved that.
To say the CMOS RAMS were old would qualify for understatement of
the year award: They were 5 year models (Suffix Y) datecoded in '89.
I used the "MREAD" GPIB command to make a backup copy of the CALRAM
chip to my computer, before unsoldering all three CMOSRams and
mounting new ones (in sockets).
Afterwards I checked the old CMOSRAM's battery state, by measuring
the voltage over the GND and VCC pins in 10GOhm input mode and
found a healty 2.9something volts.
This is a point I think many of us overlook:
If the meter has been turned on 24/7, the lithium cell does not do
anything but sit there, and the reverse current of the diode that
separates it from the chip is often enough to keep the battery in
fine shape, despite the fact that it is not in any way shape or
form intended to be rechargeable.
And I think it is pretty safe bet that most HP3458A's are left powered
24/7, because that avoids the entire issue of warm-up etc.
But yes, eventually you will run out of battery, but it was probably
the easiest chip I have ever unsoldered: the holes were suprisingly
large.
So I would recommend you make a backup of the CALRAM with the MREAD
command (I described how to in a post some time back) and let your
batteries run out.
If like me, you keep the meter powered, it may never happen.
Poul-Henning
--
Small Design
Zuiddijk 354
1505 HD Zaandam
The Netherlands
tel. +31 (0)75 77 11 740
fax. +31 (0)75 77 11 742
e-mail: rob.klein@smalldesign.nl
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.