all! First post here. So I have a DDTS-100 audio decoder, for over 10 years, which I have connected to a TV, several consoles, a PC and occasionally other equipment. It's still working fine, except for a small issue that, has far as I can recall, has always been there, which is audio interference every time an optical or coaxial output is selected. This has always been easily fixed by turning the decoder off and on. Sometimes it may take a couple of times, but the moment it s turned on and there's no interference it will remain that way until the output in question is disconnected and connected again. Anyway, recently I purchased a blu ray drive for my PC, in order to watch blu rays from other regions. As usual, I'd turn the decoder off and on when the movie starts to eliminate interference. The thing is the other way I was watching a movie that uses seamless branching over several scenes, something that would always cause an audio drop that would bring back the interference, which meant I had to keep turning the decoder off and on several times during the movie, something that got old fast. So I finally decided to... see what I could do about it. A Google search didn't return any specific results, I tried to connect the AC adapter to a different outlet, an outlet with nothing else connected to it, and the interference did become less audible, but it's still there, on the optical and coaxial outputs depending on me to turn the decoder off and on to eliminate it. The AC adapter looks to be in perfect condition, it never suffered any damage, but... should I still consider buying a new one? Would that solve my problem? If not... what would? Could the issue have more to do with my apartment's wiring than the equipment? Thanks in advance :)


closed as off-topic by Brian Carlton, Wesley Lee, uint128_t, Voltage Spike, Andy aka Feb 17 '17 at 10:37

This question appears to be off-topic. The users who voted to close gave this specific reason:

  • "Questions on the repair of consumer electronics, appliances, or other devices must involve specific troubleshooting steps and demonstrate a good understanding of the underlying design of the device being repaired. See also: Is asking on how to fix a faulty circuit on topic?" – Brian Carlton, Wesley Lee, uint128_t, Voltage Spike, Andy aka
If this question can be reworded to fit the rules in the help center, please edit the question.

  • 2
    \$\begingroup\$ Welcome! Could you try to more clearly structure your text, by adding empty lines between logical paragraphs, and maybe highlighting your central question? This being a bit hard to read reduces the chance of it getting good answers! \$\endgroup\$ – Marcus Müller Feb 17 '17 at 1:13
  • \$\begingroup\$ It sounds like a flaw. Have you tried support? CLI.Customerservice@customercare.creative.com post a picture of the power supply label and describe the hum. Does it buzz or just bass hum? have you tried short coax outputs, in case of Op Amp oscillation with capacitive loads triggered by a transient. \$\endgroup\$ – Sunnyskyguy EE75 Feb 17 '17 at 1:34
  • \$\begingroup\$ Giving double space after the sentence will take you to new paragraph. \$\endgroup\$ – Umar Feb 17 '17 at 1:36
  • \$\begingroup\$ 1) What kind of AC Adapter do you have? Is it an old-fashioned unit (large, heavy) or a newer Switch Mode type (relatively light)? 2) What are the power requirements for your device? 3) Do you have access to test equipment such as a DMM or oscilloscope? Please modify your question with answers to the above and we will do what we can to help. \$\endgroup\$ – Dwayne Reid Feb 18 '17 at 16:59

One way that I've used to defeat hum is throw an ferrite inductor or a toroid choke around the wire connected to your device. The noise might not be conducting through that wire, maybe another wire, so it might take some effort to find which one it is.

If you have a toroid wide enough you can coil the wire around the inside with a few turns (if the connector will fit through)

You can buy clip on inductors from many sources. They clip onto the outside of the wire and increase its inductance.

By increasing the inductance you create impedance (or an equivalent is resistance) for high frequency signals, which are usually the ones that create interference.

I've used this for a clock radio (I had a powerline adaptor that sends high frequency signals to transmit network information) and for audio cables in my car (to block high frequency signals from DC to DC converters from 12V devices from getting into my car radio)


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