30年以后,Keysight 终于更新了 3458



  • 1989年,HP推出了3458,在8位半万用表中出货量毫无争议的第一,因应了多种多样的玩法,包括满足垃圾佬的虚荣。

    在2019,看到Fluke推出了 8588 以后,Keysight 终于坐不出了,挤牙膏似的推出了黑色版3458A,并且承诺在有限的未来推出全新的继承者,让我们拭目以待,感受一下冷战以后仪器巨头在万用表的创新诚意。

    00dcd25d-3431-48c8-8e6a-6ebf3eaae625-image.png
    Hello folks - the RoHS compliant revised version of the 3458A will be launched soon - 1st of December 2019 - in Germany by Datatec / Meilhaus and authorized KS distributors ... Some of us have already seen the early model or a presentation.

    Keysight 3458A | 8½-digit digital system - bench multimeter:

    Back in Black - the legacy model did not meet EU RoHS compliance requirements and was discontinued. Keysight reworked the 3458A fundamentally. In terms of RoHS compliance, Keysight has made a major overhaul of all its printed circuit boards for the 3458A. The revised 3458A is 100% compatible with your existing 3458A.

    The 3458A Multimeter features an 8½-digit display, an accuracy of 0.0008% for DCV (0.0004% optional), the highest stability of 8ppm per year, combined with very fast measurement speeds with very high absolute accuracy , Therefore, the 3458A is the standard in calibration and calibration laboratories, in production fields and development laboratories around the world.

    The 3458A is used for high precision DC and AC voltage measurements and DC current measurements. Applications can be found in test rigs for different tasks in meteorological institutes, development laboratories and production, where the high measuring speed is also advantageous.

    What has been kept unchanged ?
    Fully compatible: Same form, fit and function. Same specifications as released in 1989. Same programming codes. Same I/O connectivity. Same part number and accessories.

    What Has Changed?
    RoHS compliant. New color. New PCB assemblies (DC input board, AC board, A/D board, out-guard controller board, in-guard power supply board, out-guard power supply board). Extended memory (former option 001) is now standard.

    KS will most likely propel the development of a high end DMM designed from scratch - to be expected in a few years from now.

    Knowing that KS will focus efforts more on development of new products and the 3458A is more a cash cow - it is right moment to make a wishlist of accessories, software code snippets (Python language), ... that would be welcome with the introduction of the black edition of the 3458A - so that KS can work on that to extend the lifespan of this DMM beast ...

    What would 3458A adepts like that KS focuses on next coming months ... ?

    Outdoor carrying case ...
    Python3 & RPi code snippets ...
    Improved A9 reference board - 2ppm/YR - lower 1/f noise - lower TC @ lower cost using recent technology...
    Improved A3 ADC board - new U180 with lower TC - vacuum encapsulation (no leakage)
    Any other business ... (?)

    Herzliche Grüße/Meilleures salutations/Best regards
    ScoobyDoo

    备注:

    1. 感谢 pipiline 的报料。
    2. 原贴:https://www.eevblog.com/forum/metrology/3458a-black-edition/?all


  • 改进点?

    1. ADC改进为密封陶瓷?

    b9db9202-45fd-4301-aa9b-6b2a8d24cf96-image.png
    原来封装,已经为陶瓷,但是盖子的密封是用胶水,多年以后密封性会变差,导致内部器件氧化,待求证。

    49acfffa-409d-4d61-b73a-e8cf9d535f93-image.png
    可以采用的改进封装,同样是陶瓷壳体,但盖板变更为可伐合金,内部充氮,金锡焊片焊接,从而达到长寿命和可靠性的目的,这也是现在高可靠性的主流封装形式之一。

    2. 用户界面

    为了更好发挥3458的高性能,界面可以采用为344xx系列的TFT图形界面,比如可以很好的看到50k 采样率的波形。

    83767cb8-49c1-4b1c-a172-33b65330c0d2-image.png

    这一部分确实可以修改了,因为距xDevs的报料,最先进的逻辑器件不过是Xilinx Spartan-II XC2S30,连 rigol 都在大量使用 Zynq 7 器件。

    All digital glue logic, spotted in number of DIP packages on older A5 boards is now moved to Xilinx Spartan-II XC2S30 in PQFP-208 package. This little FPGA have 972 logic cells (30K gates), have 92 I/Os and 24K of onboard RAM。



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  • 这个据说是内部?

    mmexport1574264079499.jpg



  • @redtony 这个是早期的 ADC 板。 xDevs.com 上有详尽的年份分类。

    xDevs.com 3458A A3 板



  • @赖子 ,懒!

    A3 ADC Board
    A/D Converter board is heart of instrument popularity and performance. It’s capable of performing 16bit (corresponding to 4½-digit resolution) conversions at 100kSPS speed or full 28bit (8½-digit mode) conversion at 6SPS, with <0.1ppm linearity.

    a3_top_1.jpga3_bot_1.jpg
    Image 92-93: HP 03458-66503 analog to digital converter, top and bottom side

    Worth to note, not all 3458A’s have same A3 board. There are multiple A3 board revisions, and schematics in CLIP is for one of first revisions. There are some important differences, not reflected in this old schematics.

    0844e7f0-3bb8-4d10-8ac8-8579558f5d4a-image.png
    Table 10: Different revisions of A3 PCBA

    Close-ups on PCBA components

    a3_opamps_1.jpg a3_lincap_1.jpg a3_asic_1.jpg a3_asic2_1.jpg a3_logic_1.jpg a3_mcu_1.jpg

    Image 94-99: A/D PCBA circuits

    This board also features its own Intel 8051 microcontroller, with mask firmware 03458-85501. This MCU is orderable from Keysight.

    ADC board interfaces to Outguard main processor thru 2Mbit bidirectional UART optical link, using fiber Avago’s Versatile Link cables. HP have related PDF-document covering this application as well.

    a3_optic_1.jpg
    Image 100: VersaLink optical isolation interface

    Since our unit have S/N later than 2823A00700 and also ERC is 3519 we don’t need modification covered in Service note 3458-01C, my board have mentioned capacitors 15uF 10VDC. There is installation manual available for A3 board replacement.



  • 起码把显示屏改一下,软件改一下,与时共进,也算是进步和提升!可惜只是打了一个环保口号,仪器才多大的量啊!



  • 只要能把大骗子的步步高毛病改好,价格不变。其他问题也就忍了。



  • 看参数应该是基准默认升级为2ppm/yr,温度系数更低。
    希望能解决大骗子步步高问题,然后把电阻测量的性能提高到八味办应有的水平,屏幕可以换成全点阵vfd或者彩屏;
    价格继续保持或者不要增长太多(10W以内)。
    还是很不错的。



  • @Ikaros 什么 “大骗子步步高” 的问题?



  • @赖子 3458ADC板上那片ASIC失效导致的读数步步攀升或者连续下降的故障。



  • @Ikaros 这个问题后期已经解决了,见 3458A-18A Service Note 。

    3458A-18A Service Note



  • @赖子 还是要感谢您!TIM截图20191124132610.png



  • @赖子 治标不治本的懒人做法,还是没有从根本上解决这个问题。



  • @skywind 那颗 U180 就是数颗精密电阻和模拟开关集中在一个封装内,等它稳定后就没事了。



  • @赖子30年以后,Keysight 终于更新了 3458 中说:

    @skywind 那颗 U180 就是数颗精密电阻和模拟开关集中在一个封装内,等它稳定后就没事了。

    这是我今年见过的最不好笑的冷笑话了。



  • @skywind 可有好建议?



  • If somebody wants particular test on 3458A Black, let me know. Will do usual SN18, INL, stability, noise and ACAL tests.



  • @TiN30年以后,Keysight 终于更新了 3458 中说:

    If somebody wants particular test on 3458A Black, let me know. Will do usual SN18, INL, stability, noise and ACAL tests.

    @TiN what is SN18 test?



  • Verification of ADC gain stability. Good ADC must drift below 0.012 ppm/day.