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Thread: 4.2 Build Works except... unable to power Pi from 12v

  1. #1
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    Question 4.2 Build Works except... unable to power Pi from 12v

    So I built my 4.2 heatermeter in the fall, and it went well. Once my build was complete I was able to successfully load everything up. Everything works great when powered from microUSB on the pi.

    However, the 12V supply never worked for me, it never did anything. Using the schematic (https://github.com/CapnBry/HeaterMet...roubleshooting), I was able to identify a bad 5v trace on my board between IC1 and the 100u/10 cap next to it. I jumped the two pins with a bit of wire. Now I can run my heatermeter from the 12V supply, but the rPi still won't boot.

    I have rechecked ever pin with a labeled voltage on the schematic, and they are all accurate (including the GPIO pins), however I cannot get the pi to boot. The PWR LED turns on solid, but I never get any ACT, and attaching it to a monitor I get no output. I have left it alone for up to 10 min.

    Any recommended troubleshooting steps?

    Thanks

  2. #2
    TVWBB Wizard Steve_M's Avatar
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    The PWR LED coming on is a good sign that it's getting power. I would re-write the HM image to the SD card and try again.

    You can also try powering the RasPi using micro USB connector on the Pi, but be sure that that 12v power supply is not connected to the HM board before doing so.

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    Quote Originally Posted by Steve_M View Post
    The PWR LED coming on is a good sign that it's getting power. I would re-write the HM image to the SD card and try again.

    You can also try powering the RasPi using micro USB connector on the Pi, but be sure that that 12v power supply is not connected to the HM board before doing so.
    Everything works perfectly from the micro USB. Pi boots, probes log to it, etc. The pi just won't boot from 12v. That's what makes this so frustrating.

  4. #4
    TVWBB Wizard Steve_M's Avatar
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    If you had to fix a 5v trace on the board, perhaps there might be more on the board needing some fixing. Post a couple of high quality pics of the front and back of the HM board.

  5. #5
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    Sorry for the belated response. It took me a couple days to find time to take pictures. After I took photos, I ran my first cook with my meter (yesterday). I power cycled the meter probably a dozen times. 12V vs microUSB, with and without the pi, etc. Never did get it working.

    Brought it in last night after the meat was done and plugged it in with pi attached, using 12V and now everything is working. Who knows, lol.

    Thanks for the time Steve.

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