After using a couple of S26 smart plugs for a week I ordered some more as I was happy with them. I opened the new batch up and immediately spotted some terrible soldering and even a missing resistor. I opened up the first batch I ordered and spotted issues on those too.
Here’s a photo of all 4 sonoff devices with issues marked:
The pads you mention in A are on the same “pad” they are connected together, that’s one of the mains cables so needed a lot of heat to flow the solder.
B & C are connected together on the ground planes.
D is a decoupling capacitor. It’s component C1 not R17
E again are connected together.
You tend to get bridges like that when there are large ground planes as you need a large amount of heat to get the solder to flow.
If you are unsure if you use a multi-meter set to continuity mode you can test all the connectors on plug one. You will see each point is joined together where you have solder bridges on the others.
Don’t get me wrong, I’d love to trust these devices as I think they’re great but this has cast some doubt in my mind due to my limited knowledge of what I’m looking at and the apparent inconsistencies between each of the devices. I’ll do as you say and check the connections with a multi-meter, thanks.
Regarding the missing component C1, is this a major issue? Should I return it for a replacement or is it possible to identify the component and solder one on myself? I can’t see a number on it anywhere.
Yeh I found the S20 schematic and determined the same. I got them from Amazon. I have emailed itead directly and sonoff via Amazon. The offending socket has been working fine for a week, I’d just like to make sure it’s 100% to spec. Thanks again for your help.
Bridging the pads is totally Normal. It’s actually by design. On the PCB trace the metal is um thick and there’s a lot of
potential current. The solder blobs increase the cross sectional area and help conduction. It’s intentional. Missing smc is concerning but likely inconsequential.
