Life span of hardware? (emonTx or CT clips)

Hi all, just trying to figure out if it’s worth me spending a lot of time on this.

Pulled out an old emonTx, I’m guessing 5-10years old, one of the early ones.

One CT clip seems to show negative draw regardless of direction, the other shows 0 all the time even though I know I’m using power. Swapping inputs, (CT1 to CT2) the error follows so I’m guessing it may be the CT clip but I’m not sure…

One input (CT3) was tracking fine for 3 days and then now shows 0…

I’m not keen on wasting money buying new CT clips and then finding the Tx unit is on the fritx either, rather just buy all new gear if life span is old?
Do CT clips fail?
Any suggestions?

Thanks, Josh

Pulling out from where? Has everything been in use or in storage? What general conditions - tropical, temperate, damp?

I have an emonTx V2.2 dating from roughly early 2012, along with the grey-cable, soldered plug YHDC c.t’s of the same date, a NanodeRF and emonGLCD.
The emonTx is fine, I used it extensively when developing emonLibCM because of the accessibility of the I/O for probing with a 'scope to check timing, etc.
The GLCD was in use today, checking the messages sent by radio from an emonTx sketch I’m working on.

I take it you’ve got our standard (of the time) split-core c.t., the YHDC SCT-013-000 with the grey cable?

It depends on how you treat them. If you subject the ferrite core to any form of stress, it’s likely to snap and that’s irreparable. The winding wire is quite fine, so that too might snap if it’s been stressed either during manufacture or after. If the broken wire comes off the outside of the bobbin, that might be repaired, if the inside, you’ve no real hope. The plastic hinge might break if it’s been opened or closed too many times. Then of course there’s the cable, which is liable to damage and failure in all the usual ways.

Suggestions: Examine each one carefully, looking for anything that appears wrong. As you assembled it, you must have a multimeter: measure resistance between tip and ring of the plug. The resistance you should see is around 100 Ω, unscrew the cover on the plug and check the connections: red and white wires should be connected, the cable screen should not be.

The early emonTx had a very stiff jack socket, and it was easy to push the plug in thinking it had gone far enough when it hadn’t. You have pushed the plug home right up to the shoulder?

Is there any corrosion visible? - twisting the plug a few times should clear it if there is.

Are you using an a.c. adapter? is that giving a voltage (~ 12 V) and is the plug and socket clean?

Once you establish that you have one good c.t, you’re in a position to fault-find the emonTx. I take it you soldered the components yourself? Use a magnifying lens to look carefully at every soldered joint. Be prepared to re-solder any that don’t look right.

Thanks, good questions all and ones I hadn’t considered.
Tropical and hot climate but it’s been sitting indoors for the last few years. When it was out and in use it is hot and dusty…
The emonTX was a preassembled one and the CT clips had the black wires purchased at the time. The sockets are stiff so I’ll double check. I’ll have a look at those failure points you mentioned when I pull it all out and test.


The black wire c.t’s are rather later - I think they first appeared in early 2013, the moulded plug ones in mid-late 2017.

I’ve had a look at the shop. If I’ve got the right order, this was shipped 17th January, 2014. It’s an emonTx V3.

That sounds about right but the years are a blur for me. I’ll have to do some testing but just not sure where to start and if it’s worth the time. 7 years some things start playing up…


Thanks, Gwil. So in my terms, NOT an early one, but a V3.2?

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