Kenwood receiver no sound on FM source

[OllieBommel]

Hi,
I have a strange problem on my Kenwood receiver.
When I set the source to FM radio, I have no sound from the speakers
anymore. When I set the source to AM, or to CD or TAPE I do have
sound. So only FM is not working.
It's a kenwood 4060.
I opened the receiver, and checked all fuses but they tested ok.
Any ideas of what to check?
thanks

 

[William Sommerwerck]

All sorts of things... Bad selector switch. Broken leads. Bad FM front end.
Shorted FM IF transformer.

 

[OllieBommel]

Well,
FM does work as such. I receive channels, and the name of the channel
and the currently aired song is displayed (thru rds).
So it's only the sound output to the speakers that no longer works,
and only for FM.
It started when I tried to hook up 2 speakers per channel instead of
one.

 

[Meat Plow]

Well,
FM does work as such. I receive channels, and the name of the channel
and the currently aired song is displayed (thru rds).
So it's only the sound output to the speakers that no longer works,
and only for FM.
It started when I tried to hook up 2 speakers per channel instead of
one.

Do the other functions sound the same after your speaker experiment? If so
the loss of FM audio and the experiment are purely coincidental.

Do you have any experience in troubleshooting/repair of home electronics?
Do you have test equipment? You'll need a print, DVM and possibly a cheap
scope to fix this one.

 

[OllieBommel]

I do have a certain knowledge in pinball system board repair. So I
guess this is more or less the same.
I have a dvm and a test probe.

All other 'sources' like CD and AM radio sound very good. only fm
sound output 'disappeared'. the sound stopped while connecting the
second pair of speakers (in parallel) to the red and black speaker
crimps.

Thanks for any help

 

[Meat Plow]

I do have a certain knowledge in pinball system board repair. So I
guess this is more or less the same.
I have a dvm and a test probe.

All other 'sources' like CD and AM radio sound very good. only fm
sound output 'disappeared'. the sound stopped while connecting the
second pair of speakers (in parallel) to the red and black speaker
crimps.

Thanks for any help

A print would be useful to track down where the audio signal stops. A
high impedance audio test probe could probably be substituted for a scope.

 

[OllieBommel]

Hmmm... I guess it will not be an easy fix then?

 

[Mark D. Zacharias]

Well,
FM does work as such. I receive channels, and the name of the channel
and the currently aired song is displayed (thru rds).
So it's only the sound output to the speakers that no longer works,
and only for FM.
It started when I tried to hook up 2 speakers per channel instead of
one.

Hooking up speakers would not cause the FM problem. Could have blown an amp
channel, but then the other sources would not work.

Maybe knocked off the antenna, or as someone else suggested, the current
lack of FM could be a coincidence.


Mark Z.

 

[jango2]

Hit the FM stereo switch, set it to mono. Do you get any sound now?
When set to stereo the circuit is designed to mute any audio if the
quality and strength of the signal being received is'nt stereo worthy
( better antenna/ orientation required). Your RDS is working , else
i'd suspect FM detector transformer.
Loading 2 pairs of speakers on would'nt cause this problem , as the
rest have stated.
Jango.

 

[jakdedert]

Hooking up speakers would not cause the FM problem. Could have blown an amp
channel, but then the other sources would not work.

Maybe knocked off the antenna, or as someone else suggested, the current
lack of FM could be a coincidence.


Mark Z.

That answer resonates with me, as well, OP. Go back and *carefully*
check the antenna connection. If it looks good, unhook it anyway, and
hook it up again. You'll have to do it anyway if you repair/replace the
receiver, and it's a lot cheaper than those options.

Also, the advice in the thread about switching the FM mode is sound.
That might lead you to the same place; a bad antenna connection.

jak

 

[Meat Plow]

Hmmm... I guess it will not be an easy fix then?

Easy is a conditional term. Easy for an experienced tech with
basic test equipment. Not so easy for an inexperienced tech without
a print.

 

[Meat Plow]

That answer resonates with me, as well, OP. Go back and *carefully*
check the antenna connection. If it looks good, unhook it anyway, and
hook it up again. You'll have to do it anyway if you repair/replace the
receiver, and it's a lot cheaper than those options.

Also, the advice in the thread about switching the FM mode is sound.
That might lead you to the same place; a bad antenna connection.

jak

The OP says the receiver is getting the RDS display of the channels and
the current aired song.

 

[OllieBommel]

Hi again,
I tested some more. Jango was right in that it has something to do
with the fm signal being muted whenever it does not receive full
stereo fm. The "stereo" on the display does not light. I once managed
to quickly receive stereo and I heared the sound. But, I placed the
receiver on different locations and it seems that I never can receive
stereo fm for any length of time, which results in the muted sound.
It's a kenwood KRA-4060 and I cannot find a "mono" button on the
receiver or remote control to disable this "muting" behavior. I think
there must be something broken on the FM receiver because it never
receives in stereo, although it can always receive full RDS signal and
a lot of different channels. I think when it can receive full RDS for
a certain channel that the reception must be good enough to also
receive stereo, not? Also the "tuned" light is on which indicates good
reception. It auto-tunes to a lot of different channels. Only never in
"stereo" and because it mutes the sound on mono, I have no sound at
all. I tried a different antenna but still no luck. I really think the
reception is good enough but somehow the "stereo reception" seems to
be malfunctioning. I have a cheap small tower receiver as well on the
same location and this does receive a stereo fm signal.
It's stupid that it mutes all sound to the speaker when it does not
receive stereo... Even more stupid is the fact that I cannot seem to
change this behavior...

 

[jakdedert]

The OP says the receiver is getting the RDS display of the channels and
the current aired song.

Yeah, I know. What I don't know (don't have any receivers with this
feature) is whether the signal threshold for RDS is higher, lower, or
the same as for muting. In his latest post, he seems to be having
issues with multiplex threshold as well...leading to antenna diagnosis
again.

jak

 

[jakdedert]

Hi again,
I tested some more. Jango was right in that it has something to do
with the fm signal being muted whenever it does not receive full
stereo fm. The "stereo" on the display does not light. I once managed
to quickly receive stereo and I heared the sound. But, I placed the
receiver on different locations and it seems that I never can receive
stereo fm for any length of time, which results in the muted sound.
It's a kenwood KRA-4060 and I cannot find a "mono" button on the
receiver or remote control to disable this "muting" behavior. I think
there must be something broken on the FM receiver because it never
receives in stereo, although it can always receive full RDS signal and
a lot of different channels. I think when it can receive full RDS for
a certain channel that the reception must be good enough to also
receive stereo, not? Also the "tuned" light is on which indicates good
reception. It auto-tunes to a lot of different channels. Only never in
"stereo" and because it mutes the sound on mono, I have no sound at
all. I tried a different antenna but still no luck. I really think the
reception is good enough but somehow the "stereo reception" seems to
be malfunctioning. I have a cheap small tower receiver as well on the
same location and this does receive a stereo fm signal.
It's stupid that it mutes all sound to the speaker when it does not
receive stereo... Even more stupid is the fact that I cannot seem to
change this behavior...

Ollie, can you look at the receiver and describe the antenna terminals?
What is hooked to them? If nothing, that's *very* likely your
problem. If 'something', disconnect it. Hook it up again and see if
your problem still exhibits.

It was working until you messed around back there. It's easy to knock
something loose...which upon casual inspection still 'looks' good. In
the case of no antenna at all, you may have only had very marginal
reception in the first place (just above the muting threshold), and
adding/moving wires took the signal level to just below that point.

Check the antenna.

jak

 

[jango2]

"It started when I tried to hook up 2 speakers per channel instead of
one. "

Do you think you might have shifted a tiny slider switch behind the
unit , close to the speaker terminals?. Maybe thats where the mono
stereo switch is located in this model.
Jango.

 

[Mark D. Zacharias]

Easy is a conditional term. Easy for an experienced tech with
basic test equipment. Not so easy for an inexperienced tech without
a print.

This is beginning to sound more like a discriminator alignment issue to me.
Very common with digital tuners. A surround model might have the
discriminator buried in a module, however...


Mark Z.

 

[OllieBommel]

Well,
I previously only used this receiver for CD/Tape playback. I never
used the antenna and FM tuner. I connected those T-shaped FM wire
antenna's. Maybe these are not strong enough?
Also, on the antenna input terminal there is written "75ohm". Does
this need the antenna itself need to be 75ohm? Maybe these T-shaped
wire antenna's are not 75 ohm?

 

[William Sommerwerck]

I previously only used this receiver for CD/Tape playback. I never
used the antenna and FM tuner. I connected those T-shaped FM
wire antennas. Maybe these are not strong enough?
Also, on the antenna input terminal there is written "75ohm". Does
this need the antenna itself need to be 75ohm? Maybe these T-shaped
wire antenna's are not 75 ohm?

Stupid question... Was the FM actually working before you tried to connect
the extra speakers? That is, did you actually hear the FM playing?

A T antenna is 300 ohms, not 75 ohms -- but that has nothing to do with your
problem.

In general, if any FM tuner is working, and you live in an area of
reasonable signal strength, a foot or two of wire will pick up _something_.
If you can't get _anything_ -- something is wrong with the tuner.

If the display shows the RDS correctly for the station tuned in, then the
antenna and at least part of the tuner are working. That means something
"down the line" is kaput.

 

[OllieBommel]

Stupid question... Was the FM actually working before you tried to connect
the extra speakers? That is, did you actually hear the FM playing?

Yes, that's what confused me into thinking that something else was
broken. For a short while, the receiver was playing with the antenna.
But after a few minutes I tried to hook up the second pair of speakers
to the same terminals and the moment I did that it suddenly stopped
playing, as if some kind of fuse broke or some kind of protective
circuitery jumped in.
But for what I can read here (and I did not yet say this enough, but I
do appreciate all the help you have given, folks!) , both fm and
speaker connection would have nothing to do with each other...
Well, I think I must accept the fact that indeed something "down the
line" is broken and perhaps it's time to get it replaced with another
tuner.