SX-580 radio signal bleed to phono stage

[le0pard13]

Greetings. Short-time lurker, first-time poster, here. Recently, my steadfast little Pioneer SX-580 has developed a strange radio signal bleed to its phono stage. I've a Dual 1249 turntable connected and in-between tracks, if I have the volume up, the nearby (2.5 miles away) FM station KJLH (102.3) can be faintly heard. Strange, and happens even if the tuner is set other stations, too. When I swapped in my SX-680 it's as quiet as a mouse, so it seems isolated to the 580. Anyone seen similar, and perhaps troubleshooted it? Thanks in advance.

 

[tsd71]

Could be as simple as cleaning the selector switch with Deoxit D5.

 

[Watthour]

If the same turntable using the same interconnect cables does not exhibit the symptom on a different unit you can probably rule out those items - for now. And since the symptom occurs in all mores we can probably rule out the tuner, since the tuner board gets no power when in Phono mode.

It might sound crazy, but can you rig up a grounded metal shield around the unit to help reject the spurious signals? Aluminum foil would not be as effective as steel or some alloy containing iron. More crazy yet would be setting it on a rack in your (cold) oven to isolate it.

I know someone who lives basically UNDER a TV transmitter and they can hear voices in the wiring, their phone lines, and once reported that their toaster was talking, so I know you're not imagining it. .

 

[le0pard13]

Could be as simple as cleaning the selector switch with Deoxit D5.

Hmm...will definitely give this a go. Thinking about it, before I do that, will set up the box with my other Dual and see if it bleeds a signal with it, too. Thanks, tsd71.

 

[le0pard13]

If the same turntable using the same interconnect cables does not exhibit the symptom on a different unit you can probably rule out those items - for now. And since the symptom occurs in all mores we can probably rule out the tuner, since the tuner board gets no power when in Phono mode.

It might sound crazy, but can you rig up a grounded metal shield around the unit to help reject the spurious signals? Aluminum foil would not be as effective as steel or some alloy containing iron. More crazy yet would be setting it on a rack in your (cold) oven to isolate it.

I know someone who lives basically UNDER a TV transmitter and they can hear voices in the wiring, their phone lines, and once reported that their toaster was talking, so I know you're not imagining it. .

I'm going to set up the SX-580 with my 601 to see if I recreate the bleed over with my other turntable. If it does, I'll see if I can create a shield. I should mention, I live on top of a hill that has no overhead power or phone lines. Everything comes in under ground. I'll report my results. Many thanks for the suggestions.

 

[le0pard13]

Using contact cleaner on the selector lessened this considerably. Can barely hear that radio station now, and only when I crank the volume all the way over. Thanks for the suggestions!

 

[BobbyN]

Glad it worked for you. The radio signal is getting into the amp most likely through one of the cables. Since the radio station is close the signal at your location is strong and more times than not, the signal is "running" on the outside of the cable and going into the amp (common mode). Disconnecting them one at a time can find which cable(s) the signal is entering from. You can take a toroid or ferrite rod with a mix of #31 or #43 (mix number is important) and wrap the cable through or around as many turns as you can to attenuate the signal. If you see toroids without the mix number on it, it's only a "shot in the dark" to what it is. Palomar sells these... http://palomar-engineers.com/ferrite-products/ferrite-cores/ferrite-mix-selection
I have no connection with Palomar, I've just purchased from them in the past.

Loose or corroded connections can cause this also by acting as a detector/diode so make sure all connections are good and clean. This is why the suggestion above by tsd71 helped you when you cleaned the switch but it looks like you're still getting a little.

It's also very common to have the problem be with only certain components like what you experienced. There's too many variables to list but basically it's due to different circuitry, and/or shielding/location, etc

Bob

 

[le0pard13]

Glad it worked for you. The radio signal is getting into the amp most likely through one of the cables. Since the radio station is close the signal at your location is strong and more times than not, the signal is "running" on the outside of the cable and going into the amp (common mode). Disconnecting them one at a time can find which cable(s) the signal is entering from. You can take a toroid or ferrite rod with a mix of #31 or #43 (mix number is important) and wrap the cable through or around as many turns as you can to attenuate the signal. If you see toroids without the mix number on it, it's only a "shot in the dark" to what it is. Palomar sells these... http://palomar-engineers.com/ferrite-products/ferrite-cores/ferrite-mix-selection
I have no connection with Palomar, I've just purchased from them in the past.

Loose or corroded connections can cause this also by acting as a detector/diode so make sure all connections are good and clean. This is why the suggestion above by tsd71 helped you when you cleaned the switch but it looks like you're still getting a little.

It's also very common to have the problem be with only certain components like what you experienced. There's too many variables to list but basically it's due to different circuitry, and/or shielding/location, etc

Bob

Oh, thanks for the explanation, Bob. Makes solid sense.