Re: [volt-nuts] 3458A RAM batteries
My 3458A tested with marginal RAM when I sent it to Loveland for cal. Gary advised that I buy the replacement RAM board which uses RAM chips that have replaceable batteries (? could they be super caps?) that snap onto the tops of the chips. They sent the meter back to me with no charge other than for shipping. I bought the upgrade board and new cable which is needed because the new board is shorter than the old style, and the old cable won't reach. Then I sent it back to Loveland for cal. I think the RAM board was around $450 -- old memory in failing RAM chips in head bad batteries there too. Dick Moore ___ 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] 3458a RAM batteries - longer life if unit is continually powered?
Only on the newer (AB & AD) Dallas (Maxim) parts. All the old ones (Y) do not have that feature. Tom M. - Original Message - From: "Tom Knox" To: "Discussion of precise voltage measurement" Sent: Thursday, March 27, 2014 12:59 PM Subject: Re: [volt-nuts] 3458a RAM batteries - longer life if unit is continually powered? Date Codes can be misleading because most of this style of chip does not connect to the battery until the first power up cycle. So evl Thomas Knox Date: Thu, 27 Mar 2014 17:33:17 +0100 From: frank.stellm...@freenet.de To: volt-nuts@febo.com Subject: [volt-nuts] 3458a RAM batteries - longer life if unit is continually powered? Hi, the DALLAS datasheet specifies 10 years data retention. Quite obviously, that's the unpowered time. That time includes self discharge and RAM sustaining currents. self discharge and RAM supply current will be of the same order, i.e. < 1µA, I assume from experience. And I assume also, that those currents will vary over samples, i.e. over samples of battery and RAM. Recently, there was the case, where the CAL RAM was still alive after 24 years (instrument vintage 1989, same DALLAS date code!), but with unknown powering history. Additionally, a typical 10 years of lifetime is given also for those batteries. Therefore, in practise there will be no pronounced difference between powered / unpowered state. On the other hand, DALLAS implemented an electronic seal, so that the RAM inside the package is initially powered only after first power up. But there's no parameter in the datasheet, specifying data retention according to date code or to initial power up. The waste of energy just to extend the batteries lifetime, does not pay off. On the contrary, the MTBF time of the instrument will be consumed, the display will get bad, and here in Germany, this energy consumption would cost a fortune (meanwhile: 25+ Cents / kWh, crazy). Yes, as long the instrument is powered, the CAL RAM will not lose its content.. but what about unexpected power outages? If you save the CAL RAM and repogram a fresh one after failure, there's no need to send it to agilent. No, not any RAM error needs recalibration. Those error messages are not documented. So I've scanned the text fragments in the firmware file: RAM TEST 1 RAM TEST 2 probably refer to either to the configuration RAMs (2x32kB), andthe CAL RAM (8kB). Eror messages are: NONVOLATILE RAM HiGH /LOW CAL RAM FAILURE and known ones from other users: RAM TEST 1 HIGH / LOW So I assume, that a real failure of the cal constants only apply on message: CAL RAM FAILURE and perhaps RAM TEST 2 , as RAM TEST 1 should refer to the configuration RAMs only, HIGH to the high byte RAM, LOW to the low byte RAM. Errors of the cal RAM will manifest in additional ACAL or CAL failures. Frank ___ 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. ___ 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] 3458a RAM batteries - longer life if unit is continually powered?
Hi Poul-Henning, you've misunderstood, what I've done.. I simply searched the text fragments directly in the binary file, with a HEX-editor. I did no SW-reverse-engineering! I just wanted to identify, which failure (text) messages come up, when either the config RAMs, or the cal RAM fail... Nobody up to now reported the correct failure messages in case of failure of the 8kB CAL RAM. But perhaps you can tell from your reverse enginieering, what the error message would be? regards Frank Am 27.03.2014 19:11, schrieb Poul-Henning Kamp: In message <533452cd.10...@freenet.de>, Frank Stellmach writes: So I've scanned the text fragments in the firmware file: I have the firmware reverse engineered, and it is a fair deal more complicated than you posit, there are both checksums and hardware mechanisms involved. ___ 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] 3458a RAM batteries - longer life if unit is continually powered?
In message , Mark Sims writes: >The 3458A does have a vacuum fluorescent display and they do go >bad over time. I've seen lots of them with bad displays. Replacements >are expensive... they are a custom HP part only available from HP. The hardware interface is pretty simple though, so it wouldn't be hard to create a replacement. -- 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] 3458a RAM batteries - longer life if unit is continually powered?
Is there a command to turn the display Off? On Thu, Mar 27, 2014 at 10:28 AM, Mark Sims wrote: > The 3458A does have a vacuum fluorescent display and they do go bad over > time. I've seen lots of them with bad displays. Replacements are > expensive... they are a custom HP part only available from HP. > No vacuum fluorescent disply to worry about > ___ > 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. > -- John Phillips ___ 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] 3458a RAM batteries - longer life if unit is continually powered?
In message <533452cd.10...@freenet.de>, Frank Stellmach writes: >So I've scanned the text fragments in the firmware file: I have the firmware reverse engineered, and it is a fair deal more complicated than you posit, there are both checksums and hardware mechanisms involved. -- 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] 3458a RAM batteries - longer life if unit is continually powered?
Frank Stellmach wrote: Hi, the DALLAS datasheet specifies 10 years data retention. Quite obviously, that's the unpowered time. It is also the time at the maximum storage temperature... where the silicon has the most leakage current, and the lithium cells self discharge the most quickly. In my experience, they last easily twice to 3 times that long. -Chuck Harris ___ 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] 3458a RAM batteries - longer life if unit is continually powered?
Date Codes can be misleading because most of this style of chip does not connect to the battery until the first power up cycle. So evl Thomas Knox > Date: Thu, 27 Mar 2014 17:33:17 +0100 > From: frank.stellm...@freenet.de > To: volt-nuts@febo.com > Subject: [volt-nuts] 3458a RAM batteries - longer life if unit is > continually powered? > > Hi, > > the DALLAS datasheet specifies 10 years data retention. Quite obviously, > that's the unpowered time. > > That time includes self discharge and RAM sustaining currents. > > self discharge and RAM supply current will be of the same order, i.e. < > 1µA, I assume from experience. > And I assume also, that those currents will vary over samples, i.e. over > samples of battery and RAM. > > Recently, there was the case, where the CAL RAM was still alive after 24 > years (instrument vintage 1989, same DALLAS date code!), but with > unknown powering history. > > Additionally, a typical 10 years of lifetime is given also for those > batteries. > > Therefore, in practise there will be no pronounced difference between > powered / unpowered state. > On the other hand, DALLAS implemented an electronic seal, so that the > RAM inside the package is initially powered only after first power up. > But there's no parameter in the datasheet, specifying data retention > according to date code or to initial power up. > > > The waste of energy just to extend the batteries lifetime, does not pay off. > On the contrary, the MTBF time of the instrument will be consumed, the > display will get bad, and here in Germany, this energy consumption would > cost a fortune (meanwhile: 25+ Cents / kWh, crazy). > > > Yes, as long the instrument is powered, the CAL RAM will not lose its > content.. but what about unexpected power outages? > > > If you save the CAL RAM and repogram a fresh one after failure, there's > no need to send it to agilent. > > > No, not any RAM error needs recalibration. > Those error messages are not documented. > > So I've scanned the text fragments in the firmware file: > > RAM TEST 1 > RAM TEST 2 > > probably refer to either to the configuration RAMs (2x32kB), andthe CAL > RAM (8kB). > > Eror messages are: > NONVOLATILE RAM HiGH /LOW > CAL RAM FAILURE > > and known ones from other users: > > RAM TEST 1 HIGH / LOW > > So I assume, that a real failure of the cal constants only apply on > message: CAL RAM FAILURE and perhaps RAM TEST 2 , as RAM TEST 1 > should refer to the configuration RAMs only, HIGH to the high byte RAM, > LOW to the low byte RAM. > > Errors of the cal RAM will manifest in additional ACAL or CAL failures. > > > Frank > ___ > 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.
[volt-nuts] 3458a RAM batteries - longer life if unit is continually powered?
The 3458A does have a vacuum fluorescent display and they do go bad over time. I've seen lots of them with bad displays. Replacements are expensive... they are a custom HP part only available from HP. No vacuum fluorescent disply to worry about ___ 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] 3458a RAM batteries - longer life if unit is continually powered?
Hi, the DALLAS datasheet specifies 10 years data retention. Quite obviously, that's the unpowered time. That time includes self discharge and RAM sustaining currents. self discharge and RAM supply current will be of the same order, i.e. < 1µA, I assume from experience. And I assume also, that those currents will vary over samples, i.e. over samples of battery and RAM. Recently, there was the case, where the CAL RAM was still alive after 24 years (instrument vintage 1989, same DALLAS date code!), but with unknown powering history. Additionally, a typical 10 years of lifetime is given also for those batteries. Therefore, in practise there will be no pronounced difference between powered / unpowered state. On the other hand, DALLAS implemented an electronic seal, so that the RAM inside the package is initially powered only after first power up. But there's no parameter in the datasheet, specifying data retention according to date code or to initial power up. The waste of energy just to extend the batteries lifetime, does not pay off. On the contrary, the MTBF time of the instrument will be consumed, the display will get bad, and here in Germany, this energy consumption would cost a fortune (meanwhile: 25+ Cents / kWh, crazy). Yes, as long the instrument is powered, the CAL RAM will not lose its content.. but what about unexpected power outages? If you save the CAL RAM and repogram a fresh one after failure, there's no need to send it to agilent. No, not any RAM error needs recalibration. Those error messages are not documented. So I've scanned the text fragments in the firmware file: RAM TEST 1 RAM TEST 2 probably refer to either to the configuration RAMs (2x32kB), andthe CAL RAM (8kB). Eror messages are: NONVOLATILE RAM HiGH /LOW CAL RAM FAILURE and known ones from other users: RAM TEST 1 HIGH / LOW So I assume, that a real failure of the cal constants only apply on message: CAL RAM FAILURE and perhaps RAM TEST 2 , as RAM TEST 1 should refer to the configuration RAMs only, HIGH to the high byte RAM, LOW to the low byte RAM. Errors of the cal RAM will manifest in additional ACAL or CAL failures. Frank ___ 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] 3458a RAM batteries - longer life if unit is continually powered?
Always best to keep it on. No vacuum fluorescent disply to worry about so it's only the cost of power. The back up battery will last much longer. It may even be less than the shelf life as there will be a very tiny "charge" current due to the reverse leakage of the isolation diode. Robert G8RPI. From: Poul-Henning Kamp To: Discussion of precise voltage measurement ; new Sent: Wednesday, 26 March 2014, 17:58 Subject: Re: [volt-nuts] 3458a RAM batteries - longer life if unit is continually powered? In message , "new" writes: >If the cal constants are in the RAMs and the RAM batteries go dead, >the 3458 needs to go back to Loveland, right? The CALRAM can trivially be backed up via GPIB. The backup can either be written into new NVRAM chips using a programmer or it can with some difficulty be written back via GPIB. I've explained the details in previous emails to the list (see archives) and there is software to do the backup in my "Pylt" github project. In the meantime, keeping it power on means the battery only drain by their self-discharge. -- 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. ___ 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] 3458a RAM batteries - longer life if unit is continually powered?
In message , "new" writes: >If the cal constants are in the RAMs and the RAM batteries go dead, >the 3458 needs to go back to Loveland, right? The CALRAM can trivially be backed up via GPIB. The backup can either be written into new NVRAM chips using a programmer or it can with some difficulty be written back via GPIB. I've explained the details in previous emails to the list (see archives) and there is software to do the backup in my "Pylt" github project. In the meantime, keeping it power on means the battery only drain by their self-discharge. -- 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.
[volt-nuts] 3458a RAM batteries - longer life if unit is continually powered?
The question is... if the 3458 RAMs store the calibration "magic" numbers if the ac (main) power is turned off, does it mean the RAM batteries are now under load to preserve the data? If this is the case, would it be best to leave the unit on a UPS and keep it on 24/7/365? (But... will this kill the display?) That way, it would never lose the cal magic, right? If the cal constants are in the RAMs and the RAM batteries go dead, the 3458 needs to go back to Loveland, right? Does any "RAM" error, HI, LO, etc. mean that it's time to go to Loveland? Sorry for all the questions, I'm sure they were answered in the past - I'm new here! Willy, owner of one working and one sick 3458... ___ 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.
