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Thread: Raspberry Pi Overheats Immediately

  1. #1
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    Raspberry Pi Overheats Immediately

    So, I built my first HM this week. I got everything put together, Rpi Zero W hooked up and was playing with it last night. No issues. Today I finished wiring my servo/fan and plugged it into the HM. I plugged the HM in and it started to boot up but then the LCD went blank and the LEDs seemed to indicate an issue. If I unplug the Rpi the heatermeter works fine, including the fan and servo. When I plug the Rpi into a UsB power source with or without a microsd card it gets burning hot to the touch almost immediately and doesn't respond. The HM and RPi were in the 3d printed case the whole time. Did I somehow fry this thing? Is there something I can check for? I have a Rpi 3b+ I could try but I'm afraid to plug it in. Any tips would be appreciated.

    This site seems to indicate my GPIO is somehow messed up.
    Pi Zero W Overheat

    I've been testing the voltages on my HM via the GPIO. My 5v lines are solid. The 3v3 lines are not 3.3v though. They seem to climb from 0-100mv and then start over. There is another 3.3v lead on the board near the probes and it has a solid 3.3v as well. Is that an actual problem? EDIT: The 3.3v doesn't seem to be an issue. I think that would be 3.3v FROM the Raspberry pie, which we're probably not using.
    Last edited by Ryan.Flagler; 06-06-2018 at 02:04 PM. Reason: Typos and additional info

  2. #2
    TVWBB Wizard Steve_M's Avatar
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    My guess is that something is mis-wired with the servo/fan wiring on the cat5 cable and somehow +12v has made it onto the +5v rail which has nuked the RasPi.

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    Quote Originally Posted by Steve_M View Post
    My guess is that something is mis-wired with the servo/fan wiring on the cat5 cable and somehow +12v has made it onto the +5v rail which has nuked the RasPi.
    I just double-checked all of my connections with a multimeter while the heatermeter was powered up and everything looks good. Additionally, in testing, the servo and fan controls all work as expected. I'm wondering if the timing of me connecting the fan/servo was just coincidence.

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    TVWBB Platinum Member Bryan Mayland's Avatar
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    Oof that is going to be a tough one to diagnose. You're right about us not using the 3.3V lines from the Pi as we generate our own 3.3V supply so without a Pi plugged into the HeaterMeter you'll see them as floating in voltage as if you were probing the air. It definitely seems like something shorted or the mating connector pins were misaligned when merging the Pi. I can't really think of anything else to test apart from using the voltage reference image? These are the voltages when a new fresh default HeaterMeter runs with the output at 100%.

    Oops I just noticed the "Servo" output isn't correct any more. It isn't GND it should be somewhere between 0V and 5V.
    I'm that HeaterMeter guy what ruins everybody's free time.

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    Quote Originally Posted by Bryan Mayland View Post
    Oof that is going to be a tough one to diagnose. You're right about us not using the 3.3V lines from the Pi as we generate our own 3.3V supply so without a Pi plugged into the HeaterMeter you'll see them as floating in voltage as if you were probing the air. It definitely seems like something shorted or the mating connector pins were misaligned when merging the Pi. I can't really think of anything else to test apart from using the voltage reference image? These are the voltages when a new fresh default HeaterMeter runs with the output at 100%.

    Oops I just noticed the "Servo" output isn't correct any more. It isn't GND it should be somewhere between 0V and 5V.
    Thanks Bryan, I'll test all of the GPIO headers and retest the RJ45 connector as well. What does the "F" in the white circle represent?

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    Quote Originally Posted by Ryan.Flagler View Post
    Thanks Bryan, I'll test all of the GPIO headers and retest the RJ45 connector as well. What does the "F" in the white circle represent?
    "Floating"

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    So using the image provided by Bryan I double checked all of my voltages. Everything came back normal with fan running 100%. So, I took the plunge and plugged in a new Raspberry Pi. So far, it's working without issue, so who knows what happened to the first one. Mystery unsolved.

    Thanks for the help!

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