Re: [volt-nuts] Serious problems fluke 731A, 720 and solartron
Fred,
I have recently acquired a Solartron 7081 and have had a lot of fun getting
to know the meter. In an effort to get it 'calibrated', I chased down the
US branch of AMETEK, the company that now apparently owns Solartron. I
shipped my meter to them yesterday and they will ship it to England for
calibration, repair and alignment, as needed. The 7081 ceased production in
1998 and full support ended in 2008 but it is still supported, 'best
endeavours'.
When I was on the phone with them this AM to give them my credit card
information, I asked if they still supported the 7061, remembering this
thread. She said the 7061 is still on the list of supported equipment. So,
worst case scenario, you could contact AMETEK and see what options might
exist for your 7061.
Joe
-----Original Message-----
From: volt-nuts-bounces@febo.com [mailto:volt-nuts-bounces@febo.com]On
Behalf Of Fred Schneider
Sent: Thursday, September 29, 2011 5:35 PM
To: Discussion of precise voltage measurement
Subject: Re: [volt-nuts] Serious problems fluke 731A, 720 and solartron
The voltage collapses. I have to measure how much but not just a few uV.
More like 200 mV if I remember it right. I know it is a resitive divider but
the influence on each other is getting worse if it is on 24/7, another sign
something is wrong. The 1V influences akso the 10 V so you keep it
adjusting. If i set 10 V correct and then the 1 V's the 10 V is off again.
The 845 AB had its nicads removed and they placed a big zener instead. The
most important thing, I made a regulated and good filtered powersupply. I
placed the pcb for that in the space the nicds were mounted.
I also have a HP frequency standard that had a batterybox. But they were
dead and i did not needed that so now i build a trimble thunderbolt into
that space and used the 100 KHz output of the HP for the 10 MHz. That is the
advantage of having gear with a battery option ;-)
I can think i can fix the solartron Problem if I can find a service manual.
But now I can not even check the powersupply voltages because I do not know
them. Filtercaps are good.
Fred
Fred,
What happens to the 10 volt position of the Fluke 731 when you attach a 10
MegOhm input Voltmeter ?
I am sure you know that the 1 volt positions are just resistive dividers
and any loading of any kind will drop their value.
Also, could you give details on what modifications you made to the 845AB ?
thanks,
Bill....WB6BNQ
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volt-nuts-request@febo.com wrote:
After I mounted new batterys, did some repairs I calibrated it, I
left it on for about a month. Today I checked it again and it was
drifted about 40ppm. But the problem now was I can not get it right.
It was allready a problem, allmost all adjustments influence each
other. I do not think that is normal. The manual is not realy clear.
They do not adjust the 10 V. I think it should be. They set it at 10
V position, then use a null detector to set a calibrator at the same
voltage as the 731A. But that is not 10 V in my case.
I looked in the schematic and the cal pot in the front should be the
one for that i think. They do not mention it only at the last line
for setting the standardcell value. In my manual an employer of the
former owner has placed a cross over that part of the procedure.
But if I set 10V right and 1V correct the 1.018 and 1.019 are 1.020
and 1.021 with the potentiometers at the extremes.
Also not ood I think, I can not connect a 10 MOhm voltmeter to it,
the voltage will drop then. I do not know if that is correct. But I
am afraid there is something really wrong. But not what. It is just a
Vref and a opamp. Not much other parts. It also reacts on a
powersupply change, so slowly drops in value if the battery is on. I
think the opamp is not good. But if so, it is strange the 10V can be
adjusted.
Also found out my solartron 7061 is not lineair. If I software
calibrated the 1V and 10 V range against a 332 using a null detector,
divider and a standardcell. I have a few dividers and a nulldetector,
and more meters to do some cross checkes. But If I measure, after
that, for instance 7.5 V it is spot on but when I measure 1 V in the
10 V range it is 26 uV wrong.
If I measure that value in the 1 V range it is OK but when I measure
2 V it is a bit off again. The main problem is it will not do the
null calibrating in the calibration menu. it gives an error the
difference is to big. I have the input of the rear connector standard
shorted so I do not have to take it out the rack. I allso have
replaced the battery, it now holds its values ( I think, at least the
date does) i have no service manual ( they seems to be very rare) but
I think it needs some hardware adjusting.
Third problem: my 720 is perfect, lineair in every step, except for
the B range. It is 100 ppm off in every position but this changes
sometimes from 100 to 69 if I wiggle or turn the knob. Allmost all
the isolators of my switches were cracked so I made new ones from
teflon. Cleaned everything and then it worked good. After a while the
B switch sometimes gave a fault, but turning a fewtimes corrected it
again, but now it won't. There are two switches are made complete
closed. But I can not remember if this is A and B or the two last
ones. If the problem switch turns out to be the closed one, can they
be opened. Or am am I stuck with junk in that case ? I realy like
that thing and they are hard to find and expensive. Fluke Holland
does not respond on questions about parts.
Fred PA4TIM
Fred, you can buy a manual for your Fluke 731A from
https://www.ridgeequipment.com/store/manuals/detail.php?id=12771.
From your description of all of your problems, I think it's time for some
outside assistance. You need to get one or more of your instruments checked
out and repaired by someone who has the necessary equipment to verify
operation. You don't have any equipment that is in known good condition.
Are you confident that the null meter is working properly?
I think I would start with the Fluke 332 and the 731A voltage standards.
Once you know that they are working properly and calibrated, you can then
use them to verify your 729 divider and null meter.
David
dgminala at mediacombb dot net
Hi David,
I have the original manual that came with the 731A when bought from Fluke in 1974. Inluing notes, mods ect.
The 720 Kelvin Varley is OK again, another centre isolator was cracked. I made a new one from teflon, cleaned the other switch and it is now good again. Lineair in all ranges, nice instrument
I sounds like I only have trouble but that is not true, because I have some good calibrators (332, allways giving same results in relation to the guildline, philips DC calibrator , idem, and a fluke 760) and a guildline 4 cell with full history.
I know calibration figures upto 1988 and measured them using a brand new Keithley 2000. If I take a big safety margin and extrapolate the numbers i know the value within 15 uV worst case. But the best cell dropped 50 nV a year, the worst 499 nV. The measurements with the keitley gave a inter-relation still the same as back then but then calculated on the level it must be now. The first 5 year they "settled" and after that the graphs went lineair so I calculated where they must be now and meaured them and the difference was 15 uV but the chance the 2000 is 15 uV off, is bigger then the Weston cells worn more then calculate because they were stored very carefull ( just stayed in the rack all those years it was put in when they bought it new, but never used or calibrated it, before 1988 it was calibrated every year from 1974 when produced) the oven is on the temperature it alway was.
That is why I know for sure the solartron and the 731A are not good, the 731 is not important, i made two Vrfs that are on 24/7 and they are pretty stable by now, ( 1,000.000V and 2,500.000V ) the other calibrators too. But I just like to have the 731A good also. Just for fun. It was not working when i got it. There were notes about a repair and one of he note was: need to order a new reference zener. But i do not know how good the tech at the company was, the 845 was also declared dead by him, but the repair was simple ( all gear was donated to me , fully documentated, by company that closed its cal lab) the Fluke 8500 was also written off, but I got that working again also.
Just wonder how I find out if its the Vref or the ompamp that does behave strange. I do not know if a zener reference can get "half defect" and the opamp takes over its function as good as it can. If that is possible then its the zener ( is the transistor in the reference is germanium it can be something like whiskers)
The 845AB is very good, i know for sure, i compared it to several other meters. Made some modifications to get it maximum stable.
Fred
Fred, you can buy a manual for your Fluke 731A from https://www.ridgeequipment.com/store/manuals/detail.php?id=12771.
From your description of all of your problems, I think it's time for some outside assistance. You need to get one or more of your instruments checked out and repaired by someone who has the necessary equipment to verify operation. You don't have any equipment that is in known good condition. Are you confident that the null meter is working properly?
I think I would start with the Fluke 332 and the 731A voltage standards. Once you know that they are working properly and calibrated, you can then use them to verify your 729 divider and null meter.
David
dgminala at mediacombb dot net
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Fred Schneider wrote:
The 845AB is very good, i know for sure, i compared it to several other meters. Made some modifications to get it maximum stable.
Fred
Fred,
What happens to the 10 volt position of the Fluke 731 when you attach a 10 MegOhm input Voltmeter ?
I am sure you know that the 1 volt positions are just resistive dividers and any loading of any kind will drop their value.
Also, could you give details on what modifications you made to the 845AB ?
thanks,
Bill....WB6BNQ
The voltage collapses. I have to measure how much but not just a few uV. More like 200 mV if I remember it right. I know it is a resitive divider but the influence on each other is getting worse if it is on 24/7, another sign something is wrong. The 1V influences akso the 10 V so you keep it adjusting. If i set 10 V correct and then the 1 V's the 10 V is off again.
The 845 AB had its nicads removed and they placed a big zener instead. The most important thing, I made a regulated and good filtered powersupply. I placed the pcb for that in the space the nicds were mounted.
I also have a HP frequency standard that had a batterybox. But they were dead and i did not needed that so now i build a trimble thunderbolt into that space and used the 100 KHz output of the HP for the 10 MHz. That is the advantage of having gear with a battery option ;-)
I can think i can fix the solartron Problem if I can find a service manual. But now I can not even check the powersupply voltages because I do not know them. Filtercaps are good.
Fred
Fred,
What happens to the 10 volt position of the Fluke 731 when you attach a 10 MegOhm input Voltmeter ?
I am sure you know that the 1 volt positions are just resistive dividers and any loading of any kind will drop their value.
Also, could you give details on what modifications you made to the 845AB ?
thanks,
Bill....WB6BNQ
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and follow the instructions there.
Telford Electronics in the UK have paper photocopies of the 7061 maintenance manual.
http://www.telford-electronics.co.uk/manual.php?alpha=s
Regards,
David Partridge
-----Original Message-----
From: volt-nuts-bounces@febo.com [mailto:volt-nuts-bounces@febo.com] On Behalf Of J. L. Trantham
Sent: 25 September 2011 17:31
To: Discussion of precise voltage measurement
Subject: Re: [volt-nuts] Serious problems fluke 731A, 720 and solartron
Fred,
I have recently acquired a Solartron 7081 and have had a lot of fun getting to know the meter. In an effort to get it 'calibrated', I chased down the US branch of AMETEK, the company that now apparently owns Solartron. I shipped my meter to them yesterday and they will ship it to England for calibration, repair and alignment, as needed. The 7081 ceased production in
1998 and full support ended in 2008 but it is still supported, 'best endeavours'.
When I was on the phone with them this AM to give them my credit card information, I asked if they still supported the 7061, remembering this thread. She said the 7061 is still on the list of supported equipment. So, worst case scenario, you could contact AMETEK and see what options might exist for your 7061.
Joe
-----Original Message-----
From: volt-nuts-bounces@febo.com [mailto:volt-nuts-bounces@febo.com]On
Behalf Of Fred Schneider
Sent: Thursday, September 29, 2011 5:35 PM
To: Discussion of precise voltage measurement
Subject: Re: [volt-nuts] Serious problems fluke 731A, 720 and solartron
The voltage collapses. I have to measure how much but not just a few uV.
More like 200 mV if I remember it right. I know it is a resitive divider but the influence on each other is getting worse if it is on 24/7, another sign something is wrong. The 1V influences akso the 10 V so you keep it adjusting. If i set 10 V correct and then the 1 V's the 10 V is off again.
The 845 AB had its nicads removed and they placed a big zener instead. The most important thing, I made a regulated and good filtered powersupply. I placed the pcb for that in the space the nicds were mounted.
I also have a HP frequency standard that had a batterybox. But they were dead and i did not needed that so now i build a trimble thunderbolt into that space and used the 100 KHz output of the HP for the 10 MHz. That is the advantage of having gear with a battery option ;-)
I can think i can fix the solartron Problem if I can find a service manual.
But now I can not even check the powersupply voltages because I do not know them. Filtercaps are good.
Fred
Fred,
What happens to the 10 volt position of the Fluke 731 when you attach
a 10
MegOhm input Voltmeter ?
I am sure you know that the 1 volt positions are just resistive
dividers
and any loading of any kind will drop their value.
Also, could you give details on what modifications you made to the 845AB ?
thanks,
Bill....WB6BNQ
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No virus found in this message.
Checked by AVG - www.avg.com
Version: 10.0.1410 / Virus Database: 1520/3922 - Release Date: 09/27/11
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Thanks, i have send them a mail.
Fred PA4TIM
Op 30 sep. 2011 om 21:51 heeft "David C. Partridge" david.partridge@perdrix.co.uk het volgende geschreven:
Telford Electronics in the UK have paper photocopies of the 7061 maintenance manual.
http://www.telford-electronics.co.uk/manual.php?alpha=s
Regards,
David Partridge
-----Original Message-----
From: volt-nuts-bounces@febo.com [mailto:volt-nuts-bounces@febo.com] On Behalf Of J. L. Trantham
Sent: 25 September 2011 17:31
To: Discussion of precise voltage measurement
Subject: Re: [volt-nuts] Serious problems fluke 731A, 720 and solartron
Fred,
I have recently acquired a Solartron 7081 and have had a lot of fun getting to know the meter. In an effort to get it 'calibrated', I chased down the US branch of AMETEK, the company that now apparently owns Solartron. I shipped my meter to them yesterday and they will ship it to England for calibration, repair and alignment, as needed. The 7081 ceased production in
1998 and full support ended in 2008 but it is still supported, 'best endeavours'.
When I was on the phone with them this AM to give them my credit card information, I asked if they still supported the 7061, remembering this thread. She said the 7061 is still on the list of supported equipment. So, worst case scenario, you could contact AMETEK and see what options might exist for your 7061.
Joe
-----Original Message-----
From: volt-nuts-bounces@febo.com [mailto:volt-nuts-bounces@febo.com]On
Behalf Of Fred Schneider
Sent: Thursday, September 29, 2011 5:35 PM
To: Discussion of precise voltage measurement
Subject: Re: [volt-nuts] Serious problems fluke 731A, 720 and solartron
The voltage collapses. I have to measure how much but not just a few uV.
More like 200 mV if I remember it right. I know it is a resitive divider but the influence on each other is getting worse if it is on 24/7, another sign something is wrong. The 1V influences akso the 10 V so you keep it adjusting. If i set 10 V correct and then the 1 V's the 10 V is off again.
The 845 AB had its nicads removed and they placed a big zener instead. The most important thing, I made a regulated and good filtered powersupply. I placed the pcb for that in the space the nicds were mounted.
I also have a HP frequency standard that had a batterybox. But they were dead and i did not needed that so now i build a trimble thunderbolt into that space and used the 100 KHz output of the HP for the 10 MHz. That is the advantage of having gear with a battery option ;-)
I can think i can fix the solartron Problem if I can find a service manual.
But now I can not even check the powersupply voltages because I do not know them. Filtercaps are good.
Fred
Fred,
What happens to the 10 volt position of the Fluke 731 when you attach
a 10
MegOhm input Voltmeter ?
I am sure you know that the 1 volt positions are just resistive
dividers
and any loading of any kind will drop their value.
Also, could you give details on what modifications you made to the 845AB ?
thanks,
Bill....WB6BNQ
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Think I found part of the poblem. The zero call was giving problems because a ground connection came lose. It also gave big different readings if switching polarity. After fixing this it now zeros. ( yes! ;-) )
If i do a calibration on 10 V. It showes 10.000,000 on the display, but if I switch the 720 to 1.000,000 Volt the display shows 0.999,980 Volt. If I switch the solartron to the 1 V range it reads 1.000,000.x Volt. So the 10 V range is not lineair. The stupid thing is, I can get it right. If I use the filter while meauring the 1 V in th 10 V range it is correct but then it will not read the 10 V correct. So it looks like there is some noise of common mode problem. I have not checked the 1 V range the same way. I will do that too.
Does that ring a bell to someone ?
Fred PA4TIM
Op 25 sep. 2011 om 18:31 heeft "J. L. Trantham" jltran@att.net het volgende geschreven:
Fred,
I have recently acquired a Solartron 7081 and have had a lot of fun getting
to know the meter. In an effort to get it 'calibrated', I chased down the
US branch of AMETEK, the company that now apparently owns Solartron. I
shipped my meter to them yesterday and they will ship it to England for
calibration, repair and alignment, as needed. The 7081 ceased production in
1998 and full support ended in 2008 but it is still supported, 'best
endeavours'.
When I was on the phone with them this AM to give them my credit card
information, I asked if they still supported the 7061, remembering this
thread. She said the 7061 is still on the list of supported equipment. So,
worst case scenario, you could contact AMETEK and see what options might
exist for your 7061.
Joe
-----Original Message-----
From: volt-nuts-bounces@febo.com [mailto:volt-nuts-bounces@febo.com]On
Behalf Of Fred Schneider
Sent: Thursday, September 29, 2011 5:35 PM
To: Discussion of precise voltage measurement
Subject: Re: [volt-nuts] Serious problems fluke 731A, 720 and solartron
The voltage collapses. I have to measure how much but not just a few uV.
More like 200 mV if I remember it right. I know it is a resitive divider but
the influence on each other is getting worse if it is on 24/7, another sign
something is wrong. The 1V influences akso the 10 V so you keep it
adjusting. If i set 10 V correct and then the 1 V's the 10 V is off again.
The 845 AB had its nicads removed and they placed a big zener instead. The
most important thing, I made a regulated and good filtered powersupply. I
placed the pcb for that in the space the nicds were mounted.
I also have a HP frequency standard that had a batterybox. But they were
dead and i did not needed that so now i build a trimble thunderbolt into
that space and used the 100 KHz output of the HP for the 10 MHz. That is the
advantage of having gear with a battery option ;-)
I can think i can fix the solartron Problem if I can find a service manual.
But now I can not even check the powersupply voltages because I do not know
them. Filtercaps are good.
Fred
Fred,
What happens to the 10 volt position of the Fluke 731 when you attach a 10
MegOhm input Voltmeter ?
I am sure you know that the 1 volt positions are just resistive dividers
and any loading of any kind will drop their value.
Also, could you give details on what modifications you made to the 845AB ?
thanks,
Bill....WB6BNQ
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and follow the instructions there.
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Checked by AVG - www.avg.com
Version: 10.0.1410 / Virus Database: 1520/3922 - Release Date: 09/27/11
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If i do a calibration on 10 V. It showes 10.000,000 on the display, but if I
switch the 720 to 1.000,000 Volt the display shows 0.999,980 Volt. If I
switch the solartron to the 1 V range it reads 1.000,000.x Volt. So the 10 V
range is not lineair. The stupid thing is, I can get it right. If I use the
filter while meauring the 1 V in th 10 V range it is correct but then it
will not read the 10 V correct. So it looks like there is some noise of
common mode problem. I have not checked the 1 V range the same way. I will
do that too.
Does that ring a bell to someone ?
Fred PA4TIM
The 7061 input resistance loads the 720A output. 10 Gohm should result
approximately 4ppm error.
IF the 720A is working perfectly, the input resistance of your 7061
(including connection cables) is lower than specified. Could be dust,
fingerprints...
Will
Does that ring a bell to someone ?
Fred PA4TIM
It is also possible that there is no problem. The specified linearity
of the 7061 is 2ppm of range...
According to my experience the linearity specs are pessimistic. So it
is a good idea to eliminate the other causes first.
Will