SX-980 am/fm low background hiss.

[OldschoolJC]

Happy New Year all still a newbie here recently bought a SX 980 nice unit everything works perfectly all inputs are clean no hiss no static except the AM FM tuner. If I tune off stereo with the tuner knob the hiss goes away. If I tune in on a station and flip the stereo mono switch the hiss goes away when I'm in mono mode. If I find some stations that are not broadcasting in Stereo they come in clear no hiss I am not an electronic person so I'm kind of lost so I am wondering if there's a problem inside the unit. I was told the unit was serviced but you know how that goes maybe something was missed thanks everyone for any information or help

 

[Watthour]

That could be numerous things, but most of them are going to be in the tuner multiplex decoder area.

How adverturous would you like to get with the diagnosis? What test equipment do you have available?

 

[OldschoolJC]

Thanks for getting back to me I only have a multimeter but my eyesight is not good enough to do any probing on those circuit boards would you think it's a complex issue or easily resolved but a technician

 

[Watthour]

If it is going to be sent out, it would be best to send it where alignments are done as well as general repair.

 

[OldschoolJC]

I didn't realize there would be a difference is finding someone that does that difficult I live in Massachusetts

 

[chazix]

It's not completely obvious to me from the description that anything is wrong with the receiver (though it's certainly possible). FM stereo reception is inherently noisier than mono. You might want to say what you are using for an FM antenna, and what the signal strength meter indicates when tuned in to a station that's noisy in stereo.

 

[Skywatcher]

Happy New Year all still a newbie here recently bought a SX 980 nice unit everything works perfectly all inputs are clean no hiss no static except the AM FM tuner. If I tune off stereo with the tuner knob the hiss goes away. If I tune in on a station and flip the stereo mono switch the hiss goes away when I'm in mono mode. If I find some stations that are not broadcasting in Stereo they come in clear no hiss I am not an electronic person so I'm kind of lost so I am wondering if there's a problem inside the unit. I was told the unit was serviced but you know how that goes maybe something was missed thanks everyone for any information or help

That is the nature of FM Stereo unfortunately. Only a very strong FM station with clean modulation will be quiet in FM stereo. However it is possible the MPX decoder is getting noisy. I recently had a Marantz 22 that sounded noisy in FM stereo and was also stronger on one channel. The FM Demodulator IC was the culprit. I have an SX-980 and the FM is "normal" in it given the signal strength of the local stations. A few very strong stations are quiet in stereo, but unfortunately not the kind I listen to.

 

[OldschoolJC]

Thanks for all the replies my meters show perfectly strong signal right in the middle of signal box and then the other meter for tuning also centered in the Box the local classical rock station

 

[OldschoolJC]

Should the silence on the FM stations be as quiet as inputs for let's say CD in between songs or phonograph in between songs I know you might hear the crackling of the vinyl but no hiss

 

[Skywatcher]

Should the silence on the FM stations be as quiet as inputs for let's say CD in between songs or phonograph in between songs I know you might hear the crackling of the vinyl but no hiss

No. FM is inherently noisy. Although on some very nearby stations it is very quiet. Some tuners are very good at rejecting the noise. I had an H/K 730 in for service a while back and that tuner was exceptionally quiet. Almost to the point of being "CD" quiet, but not quite that quiet. My 980 isn't even close to that quiet.

 

[Skywatcher]

Thanks for all the replies my meters show perfectly strong signal right in the middle of signal box and then the other meter for tuning also centered in the Box the local classical rock station

I have a local station 92.1 only 8 miles away. It has a very strong signal, but the "stereo" is horribly bad. Then another station 99.7 that is 40 miles away with a pretty weak signal is easily 10 times more quiet than the local, strong station.

 

[OldschoolJC]

Interesting that skywatcher has a 980 that has it also so maybe mine is just normal it's been a long time since I've been into analog FM I've had a digital AV receiver that finally blew up so I decided to go back and get old school again playing thru two sets of Sansui speakers

 

[Skywatcher]

Interesting that skywatcher has a 980 that has it also so maybe mine is just normal it's been a long time since I've been into analog FM I've had a digital AV receiver that finally blew up so I decided to go back and get old school again playing thru two sets of Sansui speakers

The thing is, the same thing happens to almost all receivers/tuners at this location with those two stations. It's not limited to this specific Pioneer. My QRX-9001 is MUCH better, but 92.1 is just a noisy station and I still have to use mono for that one. Digital FM is on a whole different level. But 92.1 also broadcasts in digital and is just as bad. It's funny though, the "religious" and Country stations all come in clear as a bell, even on the worst of analog receivers/tuners.