OpenEnergyMonitor Community

Dead emonTH? What can I troubleshoot?

Tags: #<Tag:0x00007fc9b0a63048>

Last week I received 4 EmonTH units. I had no trouble setting up 3 of them, but the first one I setup does not seem to work. When I put in the batteries (new) the LED does not light up. I changed batteries and tested the batteries to be certain.

I live in Canada so shipping back a forth a replacement seems like a last resort if there are other things for me to try first. I have experience programming ESPs and arduinos, but I don’t feel comfortable messing with it too much as it seems to be dead on arrival. Maybe someone has some suggestions?


Connect your programmer and see what it says at startup. It should print (at 115200 baud)
emonTH FW: V2.00”

then go into its setup menu. (See the sketch source on Github).
Depending on what that does or doesn’t do, we’ll decide on the next step.

I’m having issues with my programming cable because I only get garbage on the serial monitor (even with one of the working units). When I power the broken unit with batteries I don’t get any garbage on the serial monitor, but when I power the emonTH using the programmer connected to my computer, the LED lights up appropriately and it shows up in my Inputs sending temperature and humidity.

So I took the board out of its enclosure and examined it closely. I’ve attached a photo showing that L1 is not soldered into position correctly. This could very well be the only problem as the unit works with the USB cable. I believe that I can handle soldering this back into the proper position.

Thanks for your help! I appreciate it! I shall update this thread once I get a chance to try this fix (might be a couple of days)

I hope that’s the fix. It looks as if only one leg is soldered, so getting it off should be easy.

Whatever, I’ll draw it to the shop’s attention, because the manufacturing process has gone awry.

If you can’t fix it, don’t order a replacement until you’ve contacted the shop.

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Hi Dan,

Very sorry about that. If you can’t get the unit to work we’ll arrange a replacement to be sent out to you. You can PM me or email the shop: [email protected].

Thanks for notifying us, @Robert.Wall.

I’ve soldered L1 into the correct position and my emonTH unit has now been reporting data for a couple of days. I’m very happy with these devices. Thanks for your help Robert and Gwilym.

Thank you to everyone involved with the OpenEnergy hardware, software, support, documentation. It is a great project!