I have successfully modified my A5 board (03458-66505) by removing the EPROM (U110), the two DALLAS 1230Y NVRAM's (U121 and U122), and the DALLAS 1220Y NVRAM (the 'CAL RAM', U132) and installing sockets at all 4 positions. In the process, I lost the data in the 'CAL RAM', the one chip I really wanted to archive. The chip seemed to read differently each time I read it using my BP Microsystems BP-1600 Universal Programmer and was, clearly, not what I would have expected. The two DALLAS 1230Y chips read consistently and I was able to archive their data with their data in a form I would have expected. I received new DALLAS 1220AD chips (Mouser did not have the DS1220Y), installed one, and turned on the meter. It presented me with a series of messages including ACAL REQUIRED, SCAL REQUIRED, SECURE REQUIRED, and ALL CAL REQUIRED. It passed the SELF TEST and, otherwise, seemed to work although it did not seem to read my voltage standard accurately (high by about 0.15 volts). The same thing was seen when I used the old DS1220Y. After installing the new DS1220AD, I went through the calibration procedure using my 'home' standards (homemade 14 ga. copper wire 'low thermal short', 731B, General Radio 1432-P Resistor, and 3325A level generator) after which it seems to be completely up and running as advertised with no 'messages' at turn on or 'RESET'. Before I undertook the effort to modify the A5 board, I did the 'CALNUM?' command and it returned '1'. Now, when I do the 'CALNUM?', I get '13'. Of note, there are 13 separate steps in the calibration protocol. Also, I archived the DS1220AD chip after the calibration was completed, used the data to program the DS1220Y chip, installed the DS1220Y chip and it seems to be working just fine. Therefore, I have several questions: 1. What should the 'CALNUM?' command return after a first calibration with HP/Agilent (in other words, meter just delivered new)? Did my meter have a problem and someone just did the DC calibration and therefore it would return a '1'? I can't understand how I would go through the calibration procedure once and then get '13' in reply to 'CALNUM?' except for the fact that there are 13 separate steps in the calibration process. Is there some sort of 'hardware' calibration that HP/Agilent goes through that completely calibrates the meter yet only results in a '1' in response to 'CALNUM?'? 2. Is it possible to 'erase' the 'CAL RAM' by shorting certain pins together as a result of unsoldering the chip or sitting the chip, pins down, on an aluminum surface? I still can't understand how I could seemingly harvest the two DS1230Y chips without a problem and then lose the data in the 1220Y chip. The date code is from 1997 and, clearly, the battery could be a problem. 3. Are there any 'programs' installed in U121 and U122 from the factory? Or are all these just user entered programs for different measurement protocols? The point being that if I replace the chips, should I 'program' the new chips with the data archived from the old chips or just insert the new chips? I have learned a lot over the past several weeks and I really appreciate everyone's input and education. Clearly, one thing I still need to do is to establish a mechanism to 'communicate and archive' via HPIB. Had I solved that problem first, I would have been able to preserve the calibration constants. Thanks again and any thoughts and/or insight are welcome. Joe

Does your programmer have a specific setting for the Dallas chip? The Dallas chips doen't take too kindly to having an eprom's programming voltage applied.... which some programmers do even when reading. -Chuck Harris J. L. Trantham wrote: > I have successfully modified my A5 board (03458-66505) by removing the EPROM > (U110), the two DALLAS 1230Y NVRAM's (U121 and U122), and the DALLAS 1220Y > NVRAM (the 'CAL RAM', U132) and installing sockets at all 4 positions. In > the process, I lost the data in the 'CAL RAM', the one chip I really wanted > to archive. The chip seemed to read differently each time I read it using > my BP Microsystems BP-1600 Universal Programmer and was, clearly, not what I > would have expected. The two DALLAS 1230Y chips read consistently and I was > able to archive their data with their data in a form I would have expected.

In message <192B4443581F43769929FAE1F707B81C@cardiac5f772ce>, "J. L. Trantham" writes: >1. What should the 'CALNUM?' command return after a first calibration >with HP/Agilent (in other words, meter just delivered new)? Did my meter >have a problem and someone just did the DC calibration and therefore it >would return a '1'? No, I think HP cheated and reset the CALNUM counter at the factory, to avoid customers seeing "13" and wondering if they were sold a pre-owned instrument. >3. Are there any 'programs' installed in U121 and U122 from the >factory? Or are all these just user entered programs for different >measurement protocols? The point being that if I replace the chips, should >I 'program' the new chips with the data archived from the old chips or just >insert the new chips? Just insert new chips, they are empty from the factory. -- 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.

Chuck, Yes. The BP-1600 is the parallel port version of the current BP-1610. It is still supported with new software periodically. For the DALLAS DS1220 chips, it supports the 'AB', the 'AD', and the 'Y' variants with the ability to specifically select each individually. When I first got into EPROM programming, I was aware of some of the problems created by using programmers that did not specifically list the particular chip as being supported and I wanted a programmer to support all the 'old' chips possible. However, I have not measured the 'programming' pin to see if there is voltage on it when reading. Thanks. Joe -----Original Message----- From: volt-nuts-bounces@febo.com [mailto:volt-nuts-bounces@febo.com] On Behalf Of Chuck Harris Sent: Thursday, November 10, 2011 11:46 PM To: Discussion of precise voltage measurement Subject: Re: [volt-nuts] 3458A Calibration Education Does your programmer have a specific setting for the Dallas chip? The Dallas chips doen't take too kindly to having an eprom's programming voltage applied.... which some programmers do even when reading. -Chuck Harris J. L. Trantham wrote: > I have successfully modified my A5 board (03458-66505) by removing the > EPROM (U110), the two DALLAS 1230Y NVRAM's (U121 and U122), and the > DALLAS 1220Y NVRAM (the 'CAL RAM', U132) and installing sockets at all > 4 positions. In the process, I lost the data in the 'CAL RAM', the > one chip I really wanted to archive. The chip seemed to read > differently each time I read it using my BP Microsystems BP-1600 > Universal Programmer and was, clearly, not what I would have expected. > The two DALLAS 1230Y chips read consistently and I was able to archive > their data with their data in a form I would have expected. _______________________________________________ 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.