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Oscilloscopes and Logic Analyzers

HP Agilent 5382A tear down with photos

keith
February 8, 2021
5 comments

I recently tore down an Agilent E5382A Flying Lead Set. I used a Torx T-4 bit to remove the (4) tiny tiny screws.

This adapter has a 90-pin connector that comes from HP logic analyzer cards, and then goes out to single ended flying leads for direct connection to the System Under Test.

keith

Amateur Electronics Design Engineer and Hacker

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5 comments

  • You’ve very nicely provided the resistance of all of the resistors, but not any information on the component that is in series with the signal lines. Can you provide some info on that? It doesn’t look like a resistor. In fact, it almost looks like a microscopically small circuit board, so I’m wondering if it is a custom component?

    Reply

    • Hi Alan,

      I don’t really know what they are! My omission wasn’t accidental! 🙂

      Perhaps something like this ESD protection device?

      Let me ask a couple friends who might have a better idea. My knowledge of analog components, design, etc is particularly weak.

      (see my response below which should help)

      Thanks

      Reply

  • OK…. That is kind of a stupid question. 🙂 The case shows a 0.3pF cap, so I assume that is what we’re looking at. However, that doesn’t completely solve the mystery for me. The schematic shown on the case doesn’t appear to correlate with the actual wiring, so I’m guessing that the schematic is an ‘effective system’ reflective of what you can expect, and not explicit components. The double resistors to ground are not even on opposing sides of the board (I’m thinking… maybe I’m missing a via…). It really looks as though the signals come in from the flying lead connector (1 – 18), through a single series component, and then into the 90 pin connector of the probe head.

    Reply

    • My original assumption was also that it was a capacitor — and labeled my photos as such. I figured it had to be given the diagram you mentioned. However, I’ve never seen a capacitor like that in my travels, and held back from specifically saying that as a result.

      My second guess was that it was an inductor, just given the nature of that spiral trace that’s visible. Looks like a coil, maybe it is one. When I read more about inductors, though, I had a problem matching the common applications to this one. But nothing should be too surprising to the unlearned!

      My smart friends tell me that it IS an inductor, possibly made by Wurth Elektronik or Abracon, with the purpose of slowing down the edge of signal transitions in this application. A guess puts it at 3nH, but the exact value may not be critical.

      Reply

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