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Bad batch of emonTH's

As seen here: EmonTH 2 not connecting, we have had a bad batch of emonTH units. It is a power supply issue between the battery and the board - with a programmer the board works fine. Tell-tale sign is that all these boards happen be be green in colour. Will only affect people who have ordered in late December or this year. Please direct anyone affected to email the shop ([email protected]) or PM me. Thanks!

Update: not all green PCB emonTH’s are affected only a few units from the batch.

Is this something a user could repair should they prefer eg dry joint or is a faulty pcb/smd etc?

Thanks for posting @Gwil. I’ve made this thread public and pinned it to the top of the emonTH forum.

I’ll investigate this when I’m back in the office next week and post an update.

does this mean that supplying 5V through the programmer interface will make the board work?

It does indeed :slight_smile:
Are you able to test? This would help confirm it is the emonTH at fault since you are not using the regular programmer. (ref EmonTH 2 not connecting).

Also is your emonTH PCB green?

Yes, I can confirm that the board works if you supply the 5V from the programmer.
In addition to that, I can see the output from the board:

OpenEnergyMonitor.org
emonTH FW: V323
No EEPROM config
Int RFM…
RFM Started
Node: 23 Freq: 433Mhz Network: 210
Int SI7201…
SI7021 Started, ID: 21
SI7021 t: 24.23
SI7021 h: 40.10
No DS18B20

‘+++’ then [Enter] for RF config mode
waiting 5s…
temp:241,humidity:401,batt:4,pulse:1

The emonTH is now visible in the emonpi.

And yes, my PBC is green

Here are pictures of the PCB i have


It seems the faulty units are missing the boost converter chip, so not user repairable. At least on the unit we have in our hands.

Unfortunately the boost converter chip is located under the battery holder therefore we can’t see it on your photo.

Can I add the boost convertor chip myself? Will that make the board functional?

Yes. The chip in question is an LTC3525ESC6-3.3

https://octopart.com/ltc3525esc6-3.3%23trmpbf-linear+technology-442497

We would obviously be happy to cover the cost of the chip for you if you wanted to go ahead and fit it yourself. Be warned however, it’s a very fine pitch SMT! It’s possible to solder by hand (I’ve done it may times) but it’s on the tricky end of SMT hand soldering!

Will you get the chip added or would you consider selling the boards at a discount rather than binning them? I can think of a use for a permanently powered EmonTH as a pulse counter :smile:

Chips are being fitted by the factory as we speak! However we do have a few units still awaiting a chip. Happy to sell with £6 discount (£25 ex VAT + £3 shipping).

If you want to proceed please order 28 x special payment units and leave a comment at checkout stating that you would like emonTH V2 without the DC-DC converter chip:

Is it ok to buy the board with the missing boost chip that I have, at 28 x special payment units, instead of returning it?
I will try to fit the chip by myself.

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Of course, yes. But in your case you only need to pay for 25 special payment units - you don’t need to pay for shipping.

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Thank you. I will go ahead and pay for the units.

I’m curious - do you guys have a reputable source for chip components or you buy them from eBay?

Never from ebay, unless prototyping since you can’t guarantee supply quality. We use RS, Farnell and occasionally Digikey. There is a list of supplier who stock the chip listed on the octopart link I posted above.

I received the chip yesterday and I see now what you meant by

Can you give me some instructions regarding the placement of the chip on the PCB?

The little ‘*’ marks the side with pin 1