# Question on recent humming issue



## Louisiana Lost (Dec 4, 2021)

Hi everyone, first post here, I’m stuck and looking for possible things to try to fix this problem.
I have been using my Onkyo TX-SR605 receiver in the same setup for 7 years without issue. Setup is PS4 and fire stick inputs and hdmi output to tv in another room. Speakers fed into wall plate, through attic, and out wall plate to speakers. 
Yesterday I started having a low humming sound from all speakers (stronger from powered subwoofer, I guess due to frequency?) 
I’ve disconnected inputs (PS4 and fire stick) and tried switching source, but humming continues. Mostly everything I’ve found online talks about ground loop problems, but I’ve never had this issue in 7 years, so I’m thinking a mechanical issue?
Can anyone recommend something to test or try? Maybe the power supply is failing?
Thanks for any help and let me know if you need more info.


----------



## Da Wiz (May 8, 2019)

Check for a cable somewhere in the system that is not fully plugged-in or that has the shield (the outer diameter of a male RCA plug) that's been "enlarged" enough that it's not contacting the outer surface of the female RCA plug on the AVR. Find the grounding rod for your home or apartment electrical system... if you are in a drought area or if the location of the ground rod keeps the soil around the ground rod very dry all the time, apply plenty of water to the ground around the grounding rod. Get an electrical outlet tester. They are as cheap as $6 on Amazon. This will tell you if the outlet is properly grounded and whether the neutral and hot lines are wired properly. If the AVR has a 2-prong power cord, remove the trim plate for the outlet you are using for the AVR's power. If the "box" the outlet is installed into is metal, connect a 16 gauge ground wire from a panel screw on the back of the AVR and to the metal outlet box to establish a "hard" chassis ground for the AVR. If the box the electrical outlet in is blue (most plastic electrical boxes are blue), you have to find the green ground wire that may be stuffed inside the blue plastic box. Twist the green ground wire together with the 16 gauge ground wire connected to the metal chassis of the AVR and install a wire nut to keep the wires together.


----------



## gewiz44 (Oct 24, 2007)

Hello Louisiana Lost, Da Wiz has good advice. I found that when my system developed a hum that unplugging and replugging all the patch cords seemed to fix the problem. I think the small amount of current flowing creates corrosion over time, creating a poor connection which invites unwanted 60 cycle hum. Good luck, hope you find the culpret.


----------



## Louisiana Lost (Dec 4, 2021)

Thanks for the advice. I checked a few of the speaker connections and removed all connections from the back of the unit.
I did have an outlet tester, but everything was normal.
Grounding looks good outside.
I haven’t tried grounding to the unit case, but seems odd that after 7 or 8 years it would just start having this issue. 
I will definitely keep checking the remaining speaker connections.
Thanks again.


----------



## gewiz44 (Oct 24, 2007)

You're welcome, the only other thing that comes to mind is do you recall making any changes just prior to the hum occurring? Were there any new lamps or appliances plugged into the same circuit that your Onkyo TX-SR605 receiver is on? I used to pick up hum on my system when my wife used a new hair drier she bought that was plugged into the same circuit breaker. I bought one of those cool disk lightning lamps and found I couldn't use my remote when it was on. Just a thought.


----------



## Da Wiz (May 8, 2019)

Ahh, gewiz44 reminded me... look for ANY lights in your home that are on dimmers. I have found that some types of lamps that are on dimmers can induce hum in an audio system. I cannot find any correlation between resistive dimming versus "switching" dimming (that turns the power on and off very quickly... the more dim the light, the fewer the number of voltage bumps... the less dimmed the light is, the fewer low voltage moments. This switching can appear as hum. Turn all lights in the house OFF completely. Any lights you have on a dimmer... turn on one at a time to see if any of them cause a hum in the audio system.


----------

