July 10, 2019

Insteon Troubleshooting Revisited (Switching Power Supplies)

As we discussed in a previous post, power line noise is known to create problems with Insteon and other technologies that communicate over the power line.  Experience tells us that devices called switching power supplies are by far the most common source power line noise.

Switching Power Supplies

Most modern electronic devices actually operate on low voltage DC electricity.  A converter is required to power these low voltage DC devices from the 120-240 volt AC wall outlets in your home.  These converters, usually referred to as power supplies, may be built-in as is common with most television receivers and desktop computers, or may take the form of an outboard "brick" often found with laptop computers and  small printers, a plug-in "wall wart' used with cable modems, set top boxes, routers, etc., or small battery chargers used to charge cell phones and other portable electronics.  

There are two basic types of voltage converters, linear power supplies and switching power supplies.  In general, linear power supplies require a relatively large and heavy transformer while a switching power supply uses a much smaller transformer that makes it more efficient, smaller, lighter and cheaper to build.  For these reasons switching power supplies have become increasingly popular in recent years.

Switching power supplies employ a "chopper" circuit that produces high frequencies that can feed back into your homes power lines and may interfere with the normal operation of other electronic devices. 

To prevent this, switching power supplies should include an Electromagnetic Interference (EMI) filter who's sole purpose is to block these high frequencies from entering the power line.  If this portion of the switching power supply is not included in the design (for cost saving) or becomes defective, the power supply will continue to operate but can produce extreme levels of high frequency noise on the input power lines thereby blocking reliable Insteon, X10, or UPB power line communication.  Modules that utilize Insteon Dual Band technology perform better under these circumstances but very high noise levels can adversely effect even these.

Small, cube shaped, USB cell phone chargers seem to be the most common noise producing switching power supplies followed by "wall wart" type plug-in power supplies and then the "brick" type power supplies used with laptop computers and small printers.

If you are having problems linking to or communicating with any of your Insteon, X10, or UPB devices, start by temporarily unplugging all devices similar to the ones described above and retest for proper communication.  If unplugging all switching power supplies resolves your communication issues, you can isolate the defective device by plugging each power supply back into its outlet, one and a time, testing your Insteon, X10, or UPB device before applying power to the next power supply.  When the automation device fails you've found the defective power supply.  Keep in mind, you may have more than one defective power supply.

It is generally cheaper to simply replace any defective power supplies you may find.  If replacing the power supply is not practical, the noise can also be filtered out using an Insteon FilterLinc 1626-10 Plug-In Noise Filter

Good luck and contact us if we can help.

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