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Hearing radio even with no tuner connected, Yamaha Ca810

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equalizeme

New Member
Just got a Yamaha CA 810 off of eBay. It's visually beautiful, nicely cleaned up by the seller. However, even with the volume all the way down, and the tuner not selected, despite there being no tuner attached anyway, I can hear the radio. It's pretty unsettling. It doesn't matter what input or recording output I have selected, I can always hear the radio with no other active source playing. I plugged my Bluetooth receiver into the tuner input to see if just having something even attached to it would help, and unless I play music through said Bluetooth receiver, I still hear the radio.

I'm not opposed to opening this thing up to fix it even though I just got it yesterday, but I'd like to at least know what the hell could be causing this. It's kind of creepy tbh. Thus far the seller does not appear to want to do anything for me, claiming it didn't do this when it was in his living room. Well, neither did my old amp in my living room.

Noise only goes away with the amp off, or the audio muted.
 
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How close is the nearest radio station? Can you tell if it's AM, or FM?
I lived withing a 1/4 mile from a FM station years ago and I could pickup that station through the phono. A kid next door could pickup HAM radio transmissions through his portable cassette recorder. Even with it turned off.
If your speakers are disconnected, can you still hear it through headphones?
 
I'll take my headphones home from work and see. How come I could never hear the radio with my old amp? If it's external... I think it's FM but I didn't pay enough attention to what the announces were saying as I was flipping switches and changing inputs lol.
 
I've heard of this happening from crusty cables. Basically it makes a semiconductor and the wire acts as an antenna. You now have a foxhole radio even if you don't want one. Might be worth a quick run-through of all the stuff plugged into it just to verify its all clean and tight before getting too far on.

have also seen where wrapping the speaker leads through a ferrite core will shut it up.
 
gadget73 said:
I've heard of this happening from crusty cables. Basically it makes a semiconductor and the wire acts as an antenna. You now have a foxhole radio even if you don't want one. Might be worth a quick run-through of all the stuff plugged into it just to verify its all clean and tight before getting too far on.

have also seen where wrapping the speaker leads through a ferrite core will shut it up.
Click to expand...

All relatively new cables. I can try a ferrite, at least that's cheap lol. But it's disconcerting that it wasn't an issue before with my old amp.
 
Oxidized cable ends will act as a weak diode, and hence a half or full wave rectifier. Essentially a crystal set. All you need is a resonator at some AM broadcast frequency and a diode to decode the amplitude modulation into audible sound, or in this case speaker operation. Your speaker cables are probably making just the right sized loop with the crossover capacitors to make the resonator, and probably a connection somewhere in the amp or at the speaker wire connectors is acting as the decoding diode.

Those big super high power Mexican radio stations could make fences work like radios, it's a well known phenomenon.
 
HPMguy said:
Oxidized cable ends will act as a weak diode, and hence a half or full wave rectifier. Essentially a crystal set. All you need is a resonator at some AM broadcast frequency and a diode to decode the amplitude modulation into audible sound, or in this case speaker operation. Your speaker cables are probably making just the right sized loop with the crossover capacitors to make the resonator, and probably a connection somewhere in the amp or at the speaker wire connectors is acting as the decoding diode.

Those big super high power Mexican radio stations could make fences work like radios, it's a well known phenomenon.
Click to expand...
Brand new cables and speakers... Maybe I'll try cleaning the contacts in the amp?

I'm also thinking of getting a metal sheath to run the cables through.... They do are long, probably about 20ft. It's just weird because I didn't have this issue with my old amp
 
Hmm, output topology may be doing you in. Same effect with the speakers switched out?

20 ft would make a very nice AM antenna...
 
equalizeme said:
Noise only goes away with the amp off, or the audio muted.
Click to expand...

The audio muting switch is located before the power amplifier section. It seems to me that your problem is within the preamplifier (tone control) section and you're losing your time with the speaker wires.
 
So if I put my fingers around pretty much any input wire, the sound gets significantly quieter. What does that mean?

I unplugged the TT (mm input) and the noise seems completely gone....what does that mean?TT is a uturn orbit
 
equalizeme said:
I unplugged the TT (mm input) and the noise seems completely gone....what does that mean?TT is a uturn orbit
Click to expand...
what happens when you change the cartridge load impedance? Use another phono input?

It means that your cable from your turn table are of a certain length and couple with an impedance that creates a tuned circuit. Because of the amplification of the phono circuit, the minimal sound of the ad hoc circuit is amplified enough for you to hear.

Make sure all the grounds are well made and the input caps are in good shape. Experiment with different placement of the TT and routing of the cable.

if everything is disconnected and you get no radio, it’s the interface created by the TT and the amp that creates a primitive radio receiver.
 
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