Hello. I’m not sure how to contact support for store orders, I seem to be directed here, though I also sent a message from the store order area.
My emon tx unit from order #31530 seems to have died last night. It is not visible as /dev/ttyUSB0 as it always has been on the Debian box it is connected to. Also, I can’t see any lights inside it, if there are any. I have your PSU and have always used that. But I believe the box can run from the power of the USB connection of the computer also, so I tried unplugging your PSU and it still did not work. Several power cycles and reboots have not produced any change. If you agree it’s not the PSU then I can just send back the emonTX unit for you to have a look at. Or if you want to suggest any other troubleshooting steps I can do, I’ll try that. Thanks.
I have to say reported failures are rare, but it happens occasionally.
Which emonTx is it? What is “your PSU”? I don’t have access to the shop records, so without that, there’s little I can do to help you. I see you had trouble with an emonTx4 in October '23, is that it?
I would first suspect the power supply, as you say no lights are visible (and yes, there is a red LED inside, best seen if you slip it out of the case).
Are you able to measure voltages? If so, I can tell you what to measure - when you confirm what you have. If you can’t, there’s probably nothing you can do other than email The Shop ( [email protected]) if you haven’t already done so, with as much detail as you can.
It might well be worth getting a copy of KiCad and importing the Eagle CAD files from Github, so you have the schematic & board layout to hand. (If you can’t figure out how to import them, I can provide a zip version of mine.)
I suggest starting with the emonTx4. The first question is, does your custom sketch use the on-board LED? If it does, like the standard sketch, the LED should light for about 1 s on power-up (whichever way, USB or emonVs). It’s between the USB and the antenna sockets. (You might need to take one end off and slide it out of the box to see it.)
If no LED flash, about all you can do is check for 3.3V. The most accessible place is the green sockets next to the USB connector. The outer two of each set of 3 are GND (left) & 3.3 V (right). If there’s no 3.3 V there, I suspect the emonTx4’s power supply, especially if it’s fed from the USB socket.
If it’s OK on the USB power, you need to look at the emonVs.
Disconnect from the supply, take the bottom off (depending on its age & version, you might need to unplug the output cable and/or slacken the glands, and look at the end where the output cable is. You’ll find screw terminals labelled 5 V & GND - check the voltage there.
or
If it’s good, skip to checking the cable.
Otherwise, check continuity across both legs of suppressor choke L1 - it’s in circuit on early versions but shorted with cuttable links on the V1.4, and overcurrent can burn it out and put a short on the d.c. converter.
If that’s OK, check the fuse - it’s the very first component after the L1 terminal and the terminals of the Schaffner filter (U$1) are a good place to measure. N is nearest the edge and L nearest the terminals. A ruptured fuse means unsoldering and replacing.
If that’s OK, work your way towards the emonTx, checking the cable - it’s straight pin-pin.
Ok… LED does not flash on power up. But there is 3.3v on the green pins.
— a few minutes later —
Upon setting it up again, it is working!
My guess is the CPU locked up and something in my attempt to reboot it (I have a finicky setup) on initial attempts failed. But taking it away from the set up, verifying 3.3 volts dc present on the green connectors, then setting it up again was successful.
Now that’s weird - unless you never took the power off it for long enough for it to completely stop working – e.g. if the radio had locked up, it would need that to stop too (and IIRC, that works down to a lower voltage than the processor), the processor could reset but on restarting, the radio would keep it waiting forever for a response that would never come.
Might have been a combination of plugging the PSU into the pulse counter port by mistake (oops) and when I did have it correctly connected not rebooting the linux box (assuming the /dev/ttyUSB0 would appear without a reboot).
It certainly did stop working at around 9pm yesterday for no apparent reason – I didn’t notice until today though. It had been up continuously for a long time so it has been a reliable box for me.
It could well have been a short dip in the mains supply – short enough to stop something critical, but as I said, not long enough to force a full reset of everything.
