Re: [volt-nuts] Fluke 732B
Joseph Gray jg...@zianet.com writes: There was a very interesting teardown of a 732B on the EEVBlog forum. I downloaded the service manual, but it seems that the details on the voltge reference section is missing. Does anyone have a full schematic of the voltage reference? Teardown is here: http://www.eevblog.com/forum/testgear/fluke-732b-dc-standard-teardown/ Wow, nice stuff. (And so that is where all the volt-nuts traffic has gone, great thread). -- John Devereux ___ 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] Fluke 732B
Joe: The 731A and 731B were run at room temp and therefore were subject to room variations. They both use the same Reference Amplifier as the 732A B use. I have one 731B and it is amazingly stable for the room temp variations I experience at home. When I was working we had a 731B that was also very good. I had sent it for calibration over a 10 year period and the drift was equal to, or better than the 732 series. At the end of the 10 years it was absolutely stable at less than 1 ppm. This was all being done at a Fluke Service Center that was located in Milpitas California, and their 732As were being routinely sent to Fluke in Everett WA. The difference between the 731 732 is that starting with the 732A all of the temperature sensitive components were enclosed in a oven assembly that had heaters surrounding the oven enclosure which is running at 45 degrees C. This includes all of the resistors and adjustment pots. I have torn down a 732A to the oven assembly and gone inside the assembly to replace a component. It is a real trick to do this, but by being careful it can be done. The fact that the 732As have been in operation for a much longer period of time probably explains the lower drift rates than the 732Bs. The 732As have been aged much longer. I know people who prefer the 732A over the 732B because of this. The only problem with the 732A is that the heaters use more power than the 732Bs. Early manuals spec 24 hour battery operation, but later manuals have changed that to 12 hours. All of the 732As I have observed will only run for about 12 to 15 hours before the in cal light goes out meaning that the batteries have dropped below about 22 volts. The 732B is speced at 72 hours battery operation but I have no experience if this is true. I guess I am a real Volt-Nut in that I have 6 732As at home right now. I inter-compare them once a week. The last time I was able to verify what the official volt is was in 2005. Right now I need to find a good Cal Lab in the South SF Bay Area where I can have one of them certified against their traceable standards. The Fluke service center was closed years ago. Bill ___ 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] Fluke 732B
Bill, With six 732B's, you certainly qualify as a volt nut. Joe Gray W5JG On Aug 20, 2013 10:37 AM, Bill Gold wpgold3...@att.net wrote: Joe: The 731A and 731B were run at room temp and therefore were subject to room variations. They both use the same Reference Amplifier as the 732A B use. I have one 731B and it is amazingly stable for the room temp variations I experience at home. When I was working we had a 731B that was also very good. I had sent it for calibration over a 10 year period and the drift was equal to, or better than the 732 series. At the end of the 10 years it was absolutely stable at less than 1 ppm. This was all being done at a Fluke Service Center that was located in Milpitas California, and their 732As were being routinely sent to Fluke in Everett WA. The difference between the 731 732 is that starting with the 732A all of the temperature sensitive components were enclosed in a oven assembly that had heaters surrounding the oven enclosure which is running at 45 degrees C. This includes all of the resistors and adjustment pots. I have torn down a 732A to the oven assembly and gone inside the assembly to replace a component. It is a real trick to do this, but by being careful it can be done. The fact that the 732As have been in operation for a much longer period of time probably explains the lower drift rates than the 732Bs. The 732As have been aged much longer. I know people who prefer the 732A over the 732B because of this. The only problem with the 732A is that the heaters use more power than the 732Bs. Early manuals spec 24 hour battery operation, but later manuals have changed that to 12 hours. All of the 732As I have observed will only run for about 12 to 15 hours before the in cal light goes out meaning that the batteries have dropped below about 22 volts. The 732B is speced at 72 hours battery operation but I have no experience if this is true. I guess I am a real Volt-Nut in that I have 6 732As at home right now. I inter-compare them once a week. The last time I was able to verify what the official volt is was in 2005. Right now I need to find a good Cal Lab in the South SF Bay Area where I can have one of them certified against their traceable standards. The Fluke service center was closed years ago. Bill ___ 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] Fluke 732B
Joe: Thanks for the upgrade, but they are only 732As not Bs. I got all of these at less than the going price of one 732B that recently sold on the infamous action site. Bill ___ 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] Fluke 732B
Hello, until now, nobody has ever reenginered the 732B schematics. Perhaps the bbs.38hot colleagues (lymex et. al.) have done that, but I do not get access to the forum for downloading anything, either. But on eevblog, the Datron 4910 reference element has been decrypted completely, as now the content of the Vishay resistor array is known. Yep, I have to admit, that I also have made much more effort there than here lately. See 'Ultra precision reference LTZ1000'. Anyhow, in the 732B manual, there is that circuit block diagram, showing the usual reference amplifier circuitry. Fluke added some current cancellation circuitry compared to the 732A, and has put all temperature sensitive components inside the oven. That includes especially the 4-5 precision wirewound resistors around the ref. amp., which cause the most drift over temperature and time. I think that's all with 732Bs magic. The 732B had two series, one earlier with the SZA263 (Motorola) and after termination of that part, a compatible 2nd source from LT, the LTFLU refence amplifier. The mentioned Fluke / Deaver document analyses the different drift behaviour of those two components, but in general, the 732A (based on the SZA263) was less stable, afaik. 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] Fluke 732B
That's what happens when I type emails on my phone :-) I'm still envious of your voltage standards. Joe Gray W5JG On Aug 20, 2013 11:13 AM, Bill Gold wpgold3...@att.net wrote: Joe: Thanks for the upgrade, but they are only 732As not Bs. I got all of these at less than the going price of one 732B that recently sold on the infamous action site. Bill ___ 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] Fluke 732B
Frank, Have you got a link to the eevblog Datron 4910 reference element decryption? I have a 4910 and am curious to see what they found, but am not finding any reference to it in their Episode list. Thanks Steve On Aug 20, 2013, at 12:01 PM, Frank Stellmach frank.stellm...@freenet.de wrote: Hello, until now, nobody has ever reenginered the 732B schematics. Perhaps the bbs.38hot colleagues (lymex et. al.) have done that, but I do not get access to the forum for downloading anything, either. But on eevblog, the Datron 4910 reference element has been decrypted completely, as now the content of the Vishay resistor array is known. Yep, I have to admit, that I also have made much more effort there than here lately. See 'Ultra precision reference LTZ1000'. Anyhow, in the 732B manual, there is that circuit block diagram, showing the usual reference amplifier circuitry. Fluke added some current cancellation circuitry compared to the 732A, and has put all temperature sensitive components inside the oven. That includes especially the 4-5 precision wirewound resistors around the ref. amp., which cause the most drift over temperature and time. I think that's all with 732Bs magic. The 732B had two series, one earlier with the SZA263 (Motorola) and after termination of that part, a compatible 2nd source from LT, the LTFLU refence amplifier. The mentioned Fluke / Deaver document analyses the different drift behaviour of those two components, but in general, the 732A (based on the SZA263) was less stable, afaik. 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.
Re: [volt-nuts] Fluke 732B
Joe: That was a very interesting teardown of the 732B on eevblog. The one thing that this answered for me was if Fluke was using their Reference Amplifier in all of the 732B production and Fluke did. If you look at a paper by David Deaver called Predictability of Solid State References which he wrote, and you can download from the Fluke website http://us.fluke.com/. you will see on page three of the paper that he talks about the reference drifts of a number of 732Bs that were checked over a period of time. Deaver talks about Motorola References and Linear Technology References and that the Motorola's drift upwards while the Linear Tech's drift downwards over time. Also look at Fig. 10. I was assuming (wrongly of course as I see now) that Fluke had switched from the Reference Amplifier to the LTZ1000 in the production of the 732B. Now I see that it is just what company made the Reference Amplifiers for Fluke. Of course the 4 legged device is a Reference Amplifier that they have used for a least 25 years or more as the voltage reference in a lot of their instruments. I have never seen a schematic of the super secret oven assembly but you can probably bet that it looks a lot like the 732A but with a lot more black magic built into it. I don't think that Fluke would ever expect someone to fix this beyond the unit replacement level as I am sure that this would require factory precedures far beyond anything that we could muster in the field. Part of the black magic is adjusting the collector current of the reference amplifier to obtain a zero TC around a very limited range of operating temperatures. The digital adjustments also add something inside the oven assembly, probably a DAC, and it would be interesting what they are doing there, so a schematic would be interesting to see. Anyway I will quit rambling. So many things to do, so little time. Bill ___ 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.
