Introduction

These AN157-3 Z-Wave socket outlets are very good but they only switch ON/OFF and don’t have any on-board power metering. They are able to switch power at full load, have a programmable status light and are controlled by Z-Wave.

They are suitable for the control of electric heaters, Christmas tree lights, etc.

What Happened?

When this fault occurs, the plug just rapidly switches on and off (buzzes) and there is nothing you can physically do to stop it. Therefore the fault must be internal to the device. Generally the first thought is the bin and commit it to landfill but the fault is relatively easy to fix.

What Went Wrong?

Internally there is a 220uF electrolytic capacitor that goes bad. Here is a picture of a faulty capacitor side by side to a brand new one.

Generally electrolytic capacitors when they fail, the top of the capacitor slightly domes (assuming the capacitor hasn’t emptied its guts everywhere). The top capacitor is the faulty one, just carefully notice how the top of it is ever-so slightly domed, compared to the brand new component at the bottom.

How to Fix

DANGER: Do not be tempted to plug this into the mains while still dismantled because there will be lethal voltages on board. Only plug it in after the cover has been replaced and the screws inserted.

To repair the device requires you to dismantle it. There are four security screws on the rear that require removing. Once inside, the circuit board looks like the following:

The biggest capacitor (with the slightly domed top) is the one we need to replace. By doing some Googling, I found this article explaining spotting faulty capacitors here.

Replacing it is easy to do if you are skilled with electronics work. If you are not, please hand the AN157 to someone who is. You will need to desolder the two output connections to enable the circuit board to be removed.

Once removed, the capacitor needs to be replaced with a new one with the correct polarity and the whole assembly fitted back together.

DANGER: Do not be tempted to plug this into the mains while still dismantled because there will be lethal voltages on board. Only plug it in after the cover has been replaced and the screws inserted.

This is Amazing Stuff

Thanks and be careful – hopefully you can do your bit to save money and look after our planet too.

Does this work? Of course it does!