One Kiwi rocking, one DOA (no 5V, no 3.3) [fixed, power quality issue]

k5mok5mo
edited April 2020 in Problems Now Fixed
Hello All
I have two Kiwis, one I bought off of Amazon new , which is working great. I purchased a used one off of a ham forum about a year ago at a good price and set it aside as a spare.

Unfortunately, when I tried to power it up, it's DOA. Nothing. No lights, etc. I very carefully probed the Beagle DC supply pins and I see the Input supply reading correctly on the kiwi header pin but nothing on the 3.3 and 5v pins that are immediately adjacent. Doing some study here yesterday indicates that the regulated 5V and 3.3 are derived off the Beagle. I'm sure to the level of my capability that the two boards are connected together correctly.

Two questions please:

* I don't mind (too much) buying another Beagle and loading the Kiwi SW via my original SD card. Would a vanilla BBG work for this purpose?

* Is there any relatively simple diagnostics at the hardware level I could do before I spend $50 on another Beagle? While I have a nice Metcal iron with some fine tips, I'm not overly optimistic at my ability to do much SMT rework unless it's pretty simple.

I still have the SD card that came with my original Kiwi.

Thanks for any hints you all might have
John K5MO

mykiwisdr.hopto.org:8073

Comments

  • WA2ZKDWA2ZKD
    what happens if you power the BB without the Kiwi attached?
  • jksjks
    John. I replied to your forum PM yesterday, but the crappy forum code sent it to the bin instead of to you. I reproduce it below:

    Hi John,

    Please followup with email to support@kiwisdr.com Messages to the
    forum take extra work for me to deal with.

    Try removing the Kiwi board from the BBG and then powering the BBG
    alone to see if it will power-up. You’ll need a USB-A to USB-mini
    cable to do that. Preferably a short one that doesn’t have too much
    voltage drop, although this is less of a problem because the BBG alone
    will draw < 500 mA. You can use any old cellphone power supply with a
    USB-A connector. We’re just seeing if the BBG is alive.

    Yes, 5VE goes through the Kiwi board, to the BBG power management chip
    (PMIC) where it undergoes power quality checks and then back to the
    Kiwi board as 5V and 3.3V. If it doesn’t power up then the BBG is
    either dead or doesn’t like the quality of the 5VE.
  • k5mok5mo
    As John suggested, it was indeed a power quality issue. In this case, I had some significant IR drop in the small leads from the PS to the SDR. I remade a decent cable and that cleaned up the whole issue. The BB would indeed boot without the Kiwi attached, but the additional current drawn when the Kiwi was installed dragged the 5V below a tolerable level.

    Thanks to John for the excellent, patient support , and Kiwi 2 is back on the air ... I really appreciate it.
    John
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