SonOff Mini R2 switch legs measure 120V HOT?

1

Hello has any one else measured an AC voltage (60-120VAC) on their switch legs of their sonoff mini r2’s?

I just had one blow on me when one of the switch legs touched the grounded body of the switch.

I have attached pics to show how I hooked it up. I’ve hooked many of these up in the past without issues.

Maybe I got a bad batch? Maybe the power supply is poorly isolated?

(Measurements were taken on a “good” unit from the box)

Neutral to gnd measurement: 241mV AC.

Netural to gnd
Netural to gnd1920×2560 255 KB

Neutral to Vin : ~120VAC

vin
vin1920×2560 250 KB

Neutral to Vin : ~120VAC

vout
vout1920×2560 251 KB

Neutral to SW1: ~120VAC

Switch measurement 1
Switch measurement 11920×2560 252 KB

Neutral to SW2!: ~120VAC

Switch measurement 2
Switch measurement 21920×2560 250 KB

Damage seems to be to the d4 Diode between s1 and s2 on the bottom left

PXL_20211219_234654623
PXL_20211219_2346546231783×1610 411 KB

2

That is bad. There should only be 3.3v between s1 and s2.

3

You can have 120V between S1 and neutral and still have only 3.3V between S1 and S2. Devices like this tend to use cheap power supplies (e.g. capacitive droppers) that can connect the low voltage side ground to live through a diode. Not sure what Sonoff are using though.

4

Hello, this just happened to me. Diode D4 exploded. Everything else is working fine, internal button, relays and wifi works fine, I just lost the S1-S2.
Is there a way to fix it?

5

I kind of sorted it out, for anyone who blew the D4 diode here is a solution.