Postmortem Analysis of Dead Sonoff TH16 Wireless Switch

It happens I&#x27;m a bit familiar with this circuit. I think the author misread the schematic. The burned-out component is more likely the current-sense resistor R2 (4.64 ohms).<p>In any case, it&#x27;s unlikely that a 1.5 Mohm resistor would burn out like that. Ant or not, you would need a lot higher than line voltage to cause that much power dissipation over 1.5 Mohm.<p>The combination of two series 1.5 Mohm resistors R3 and R4 is actually well visible in the first photo (two undamaged components with &quot;155&quot; printed on them).

Reminds me of a LAN party with friends back in the early 90s, one of our computers suddenly shut down while playing Doom, and would not power back up.<p>We opened up the case to check for any obvious problems, like a loose connector or similar. On the motherboard, next to all the capacitors and inductors near the CPU sat a fried garden slug...

A few years back my company installed a few thousand capacitor bank controllers on the bottom utility poles. Sometime last summer, we started doing routine inspections and found a few of them covered with ants. Turns out that something in the door seal is really attractive to ants, which seems like something to avoid in a product typically installed outdoors.

Yesterday I was getting 4 new Sonoff Basic switches (2 from Gearbest, 2 from Rosegal). 2 of them were broken and looked somehow botched. Pictures (+blog post in German, sorry) <a href="https:&#x2F;&#x2F;blog.rolandmoriz.de&#x2F;2018&#x2F;05&#x2F;30&#x2F;warnung-vor-sonoff-basic-wireless-switches&#x2F;" rel="nofollow">https:&#x2F;&#x2F;blog.rolandmoriz.de&#x2F;2018&#x2F;05&#x2F;30&#x2F;warnung-vor-sonoff-ba...</a><p>While I was impressed by the Sonoff S20 build quality, at least the Sonoff basic series seem to be unreliable and even dangerous to use.

I never had this problem with bugs :)<p>I have two dead sonoff and I was expecting a more applicable postmortem analysis. In my case looks like a failure of the integrated power supply in both cases as I can power and flash the ES8266 from the TX,RX,VCC,GND pins.<p>They worked for moths and still have some others running strong.

Or, &quot;ants like flux residue!&quot;! Rosin based, aka resin based, aka probably yummy smelling for an ant!<p>I was half expecting an article on how the hardware was badly designed, but apparently, it&#x27;s rather conservative in the ratings they used -- that is, until a little mobile short moves in!

Buggy hardware will get you every time!

So its a bug?

GDPR blocked, not going to read it.

I had an electrical timer that actually stopped not of electrical issues caused by bugs but simply because it was so completely filled with earwigs that it stopped turning. I guess the few extra degrees or something was enough to attract them.