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    EEVblog #1056 – Digilent Open Scope MZ Review

    Dave looks at the Digilent Open Scope MZ Review, an $89 open source oscilloscope, logic ...

    • Maik

      Hi Dave, I think those sot23 devices on the main board aren’t transistors at all. They are labeled with “DD”, which could mean “Double Diodes”. And when I’ve seen it correctly, they are in parallel to input signals. All of the center pins are connected to a voltage rail, and the outer pins are connected to both resistor networks on the left and right of sot23 devices. So this looks like, it is just input protection for the FPGA.

    • Chris


      look at the ARM closely – is there a hole in it? (right in the middle of the chip)

      • Doesn’t appear to be on close inspection.

    • Romdump

      Hi Dave,

      I had got a similar unit to yours a while back and it was doing the same thing, (reading FF’s).

      As it turns out the AC Adapter was wrong for my country, (I am in Canada).

      Even though the AC adapter plug was physically designed for North America and the input voltage was 120VAC, the frequency was 50Hz.

      After I changed the AC adapter the unit functioned correctly. The funny thing was that before I changed the AC adapter, the software never gave me an error and detected the programmer correctly.

    • Annonymous


      You should pay attention to reference designators when you inspect unknown boards. Commonly only the “Q” designated SOTs are transistors. “V”-s are probably Zener diodes.
      Regarding DAC per pin, no you don’t need that. You need at most two DACs (unless dealing with 2708 EPROMs): one for Vcc rail and one for Vpp rail. Also, not all of the pins have to have option of connection to one of the power rails. Programmable devices pinouts are not a free art form. Manufacturers actually want people to use their new devices as soon as possible and with as little investment in new equipment as possible. Vpp position is carefully chosen, sometimes in such manner to allow existing universal programmers to support them with nothing more then a software upgrade.

      • Yeah, I should pay more attention. I view the board through the camera LCD screen, so sometimes it’s hard to spot stuff you ordinarily would.

    • It was preferable to test the device on different chip to get a better idea about the programmer.
      Testing on only one chip will not be fair (I guess).
      Unfortunatly, the video is not continued and the test is very short. More test on this device or any other programmer you like it will be greate.
      Thanks anyway…

    • Jon

      Bummer! Was really hoping to see you pull the code off that chip, that would have been really cool! I was all set to get one of those universal programmers you were using, until it bricked. My dad and I have a bunch of vintage electronics around with EEPROMS on them and I’ve always wanted to try examining the code on them. I know you are busy, but if one day you do happen to get that programmer working again, you’ve got one fan here that would love to see the process! Take care and keep up the great work!

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