• dim. 18 septembre 2016

    HP 34970A Data Acquisition Unit - communication protocol

    In order to build a replacement display for the HP34970A data acquisition unit, I needed to understand the communication protocol between the CPU board and the front panel assembly.

    General description

    The unit is built with four boards:

    • A1 is the main bard, with the PSU, the main controller and ...

  • sam. 17 septembre 2016

    HP 34970A Data Acquisition Unit - part 4

    After a summer pause, I'm back on my HP34970A replair project. In the previous post in this series, I've started to reverse ingineer the serial protocol between the CPU board and the fonrt panel, and implement a prototype of replacement display.

    OLED display

    I bought the bigest OLED ...

  • dim. 26 juin 2016

    HP 34970A Data Acquisition Unit - part 3

    As explained in the previous post in this series, I've started to sniff the serial protocol between the main board and the display panel so I can replace the failed VFD by an OLED or TFT display managed by an arduino or similar.

    Protocol

    The serial communication takes place ...

  • mer. 22 juin 2016

    HP 34970A Data Acquisition Unit - part 2

    This is quick follow up of my previous blog post on my attempt to fix my recently acquired HP 34970A.

    In my hurry to replace the failing FRAM (FM24C04) chips, I also replaced the FRAM chip on one of my 2 plugin modules.

    Bad idea: the module then provoques an ...

  • lun. 13 juin 2016

    HP 34970A Data Acquisition Unit

    I recently "scored" a HP 34970A with the DMM included and 2 plugin cards (HP 34901A and HP 34907A) for less than 200€. The plugins should be in working condition, but the main switch unit was almost "given" with the plugin modules since it is non functional.

    front view of the HP 34970A data acquisition unit

    It's in ...

  • mar. 19 avril 2016

    Tektronics 2445 scope PSU repair: part 3

    After having mostly destroyed the PSU of my Tek 2445, I've decided to be a bit less foolhardy and I've subscribed to the yahoo Tek group. I discovered that such a failure has already been reported there, also after a full recap of the preregulator and regulator of ...

  • dim. 17 avril 2016

    Lambda LPD 422 FM Bench PSU

    This post is a quick presentation and teardown of a small bench power supply I bought on ebay a few weeks ago for something like 40€.

    The Lambda LPD 422 FM dual regulated power supply.

    It's an old unit, not sure it's exact age, but the components inside the unit seem to have date codes around 1971 ...

  • sam. 16 avril 2016

    ZPB30A1 Electronic Load

    A few weeks ago, I purchased a cheap electronic load from AliExpress (this one to be precise). It's a ZHIYU model ZPB30A1. It's specifications are:

    • constant current mode
    • max voltage: 30V
    • discharge current: 0.2A to 9.99A (+/- 0.7% + 1 digit)
    • max dissipated power: 60W
    • voltage measurement ...

  • dim. 27 mars 2016

    Tektronics 2445 scope PSU repair: part 2

    After a quick repair of the PSU of my Tek 2445, I've started a more systematic replacement of the capacitors.

    Tek2445 PSU Caps being replaced.

    But I was also a bit worried because of a dirty noise coming from the preregulator area.

    After having replaced most of the electrolytic capacitors, the dirty noise became ...

  • sam. 19 mars 2016

    Building a bench 10MHz reference: part 2

    This is a quick follow-up of the first part of this series.

    I've received a few parts from digikey, including a couple of 22µH Sumida CLS62 inductors (I bought two of them in case I f**k up one of them trying to solder it with my Weller WS50 ...

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