New Build......... 12V power problems.


 

Bob Walters

TVWBB Member
I just finished putting together a Heatermeter 4.3 with a Raspberry Pi 3. When I power it via the RPi power port using the Micro USB cable, the device works fine. I can see all the menu items, adjust the probe offset, etc. etc.

However, when I try to use the Heatermeter 12volt input, I get nothing at all. So far I've only checked the terminal lugs for the input connector where it's soldered onto the board and I'm getting 12 volts there. So I've proved that my power supply is OK, but that's as far as I've gone. I've visually checked the components and solder joints and they all look correct.

The next troubleshooting step could get tedious if I have to re-flow each and every joint and check the voltages in all the places outlined in the troubleshooting guide.

Is there any clever person familiar enough with the Heatermeter to give me some hints where I could check first based on the fact that it works via the RPi. power supply but not from the normal 12 volt Heatermeter input? Does this fact indicate that I probably did NOT put one or more components in the wrong place? I would think so, but I'm electronically challenged so I don't know for sure.

Wild guesses are acceptable.
 
Problem solved. I put my strong magnifiers on and examined the boards again. There was a tiny piece of loose solder bridging one of the pins of the power MOSFET. It wasn't an actual solder trace but rather just a tiny particle which I could remove by blowing on it; perhaps a speck produced when I trimmed a component leg.

Anyway, it's working now.
 

 

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