Help with EmonTX Dead On Arrival


I'm new here, i just ordered an EmonTX and soldered it yesterday.

First, i have a dead on arrival on the AC power supply, i made a video proof here :

How is it possible ? Do i need to return this item to the sender ?

Second, despite my efforts, the EmonTX is not working.
I checked the voltage like explained, and it's 3.3v.... with USB plug.
I uploaded the first guide example with arduino, and the LED is not blinking... what can i do ?
The voltage is continuously 0.5v on the green LED, it's not blinking, only off.... :-(

Here are 2 photos of my EmonTX soldered :

I'm using the first Arduino's EmonLib "current_only" example (see my screenshot). And the upload is displayed as successful by Arduino. (using Arduino UNO, and the Programmer - USB to serial UART from openenergymonitor).

I already double checked all resistors's values, and all are right.

I don't know if i can check the capacitors now, because i think it can't be checked when connected on a circuit, but i checked before to solder to be sure of the capacities then i'm pretty sure it's ok...

How can i test the processor ?

I'm very dissapointed, is anyone can help me ?

Thank you for reading anyway !

Robert Wall's picture

Re: Help with EmonTX Dead On Arrival

Your soldering looks good to me, I cannot see anything wrong. If your sketch uploaded correctly, your processor is working. You should NOT see the LED blinking with that sketch - there is nothing in the emonLib current-only sketch to make it blink. What do you see on the Serial monitor?

Even with no current transformer connected, you should see some small numbers in two columns. I see:


I cannot read which range your multimeter is on. Because the numbers flashed when you switched on, are you sure it was on the a.c. range?

PhilThy's picture

Re: Help with EmonTX Dead On Arrival

Your meter is not set to a.c as Robert has suggested (I have the same meter) You need to press the blue button to select a.c :)

abalam's picture

Re: Help with EmonTX Dead On Arrival

Damned... you're absolutely right, i didn't set the AC range !
Thank you for this tip, and sorry for the wrong problem...

abalam's picture

Re: Help with EmonTX Dead On Arrival

Nice idea for the serial (glyn hudeson had the same idea too...), if i use the example "current_only" and open the Serial monitor, i have many values... well i guess it is working good ?

33.02 0.14
33.18 0.14
33.65 0.15
29.92 0.13
26.82 0.12
29.37 0.13
29.57 0.13

Thank you for your answers, i'm reassured.

I thought i need the green blink because of the readme here at the end of the text from "Full EmonTx Firmware's" :

I will continue my exploration of the EmonTX now :-D

Thank you again.

abalam's picture

Re: Help with EmonTX Dead On Arrival

After further tests, i think all is good. The exemple emonTx_CT123_Voltage seems to perfectly work, with the famous green LED ^^

All in need now is to correctly calibrate my three CT sensors.

Thanks again for your reactivity, and have a nice sunday !

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