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Pioneer sx-727 FM problem
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tony
Feb 10, 2012, 8:15:13 AM2/10/12
to
Hi,
I have a Pioneer sx-727. I'm the original owner over 40 years.
Recently developed fm problem.
Loud crackling sound on fm station and then station drifts. No noise
at all between stations.
AM reception also not good, background buzz, humm between
stations on AM only. Unit works perfectly with CD and other inputs.
Any ideas what my problem might be? This all started a couple of weeks
ago,
when I noticed that signal strength meter was not illuminated, I
assumed just bulb burned out.
Tuning center meter still works. Any help would be appreciated.
Thanks.
I have a Pioneer sx-727. I'm the original owner over 40 years.
Recently developed fm problem.
Loud crackling sound on fm station and then station drifts. No noise
at all between stations.
AM reception also not good, background buzz, humm between
stations on AM only. Unit works perfectly with CD and other inputs.
Any ideas what my problem might be? This all started a couple of weeks
ago,
when I noticed that signal strength meter was not illuminated, I
assumed just bulb burned out.
Tuning center meter still works. Any help would be appreciated.
Thanks.
Jeff Urban
Feb 10, 2012, 1:52:59 PM2/10/12
to
If there's no noise between stations with the muting off it's probably
oscillating. That would maybe indicate filters or bypass caps. If the
frequency actually drifts, assuming it has ONE fault which is usual,
look around the FM oscillator or mixer stages.
I think buzz between AM stations is just about normal these days,
unless you specifically noticed a difference at the same time the FM
fault showed up.
Actually RF is not really my strong suit, but it's still electronics.
If that reciever uses discrete transistors for the FM, it might be a
bit hard to find someone who really remembers how to work on it. That
reciever is old enough for a pension, but by all means try to keep it
alive.
J
oscillating. That would maybe indicate filters or bypass caps. If the
frequency actually drifts, assuming it has ONE fault which is usual,
look around the FM oscillator or mixer stages.
I think buzz between AM stations is just about normal these days,
unless you specifically noticed a difference at the same time the FM
fault showed up.
Actually RF is not really my strong suit, but it's still electronics.
If that reciever uses discrete transistors for the FM, it might be a
bit hard to find someone who really remembers how to work on it. That
reciever is old enough for a pension, but by all means try to keep it
alive.
J
William Sommerwerck
Feb 10, 2012, 1:03:17 PM2/10/12
to
"Jeff Urban" <jurb...@gmail.com> wrote in message
news:eac31162-9ea1-4f4c...@sk8g2000pbc.googlegroups.com...
> If there's no noise between stations with the muting off it's probably
> oscillating. That would maybe indicate filters or bypass caps. If the
> frequency actually drifts, assuming it has ONE fault which is usual,
> look around the FM oscillator or mixer stages.
What about a dead LO or mixer?
If you have a 100MHz 'scope, you should be able to trace through the front
end and IF.
news:eac31162-9ea1-4f4c...@sk8g2000pbc.googlegroups.com...
> If there's no noise between stations with the muting off it's probably
> oscillating. That would maybe indicate filters or bypass caps. If the
> frequency actually drifts, assuming it has ONE fault which is usual,
> look around the FM oscillator or mixer stages.
If you have a 100MHz 'scope, you should be able to trace through the front
end and IF.
tony
Feb 10, 2012, 2:52:26 PM2/10/12
to
On Feb 10, 1:52 pm, Jeff Urban <jurb6...@gmail.com> wrote:
> If there's no noise between stations with the muting off it's probably
> oscillating. That would maybe indicate filters or bypass caps. If the
> frequency actually drifts, assuming it has ONE fault which is usual,
> look around theFMoscillator or mixer stages.
> If there's no noise between stations with the muting off it's probably
> oscillating. That would maybe indicate filters or bypass caps. If the
> frequency actually drifts, assuming it has ONE fault which is usual,
>
> I think buzz between AM stations is just about normal these days,
> unless you specifically noticed a difference at the same time theFM
> fault showed up.
>
> Actually RF is not really my strong suit, but it's still electronics.
> If that reciever uses discrete transistors for theFM, it might be a
> I think buzz between AM stations is just about normal these days,
> unless you specifically noticed a difference at the same time theFM
> fault showed up.
>
> Actually RF is not really my strong suit, but it's still electronics.
> bit hard to find someone who really remembers how to work on it. That
> reciever is old enough for a pension, but by all means try to keep it
> alive.
>
> J
Thanks for the info.
> reciever is old enough for a pension, but by all means try to keep it
> alive.
>
> J
I looked at the AWR-011, Power supply unit board.
Anyone know what the tolerance should be on these voltages.
For the AWR-011, Power Supply unit board
the schematic says
pin 2,5,6,7 12.5v, 30v, 30v, 36v
I'm measuring
pin 2,5,6,7 10.5v, 27.5v, 27.5v, 33v
Is this within tolerance?
Also anyone know what the output of the big transformer
(ATT-050)should be
Nothing listed on the schematics.
I'm measuring
pins 13, 12, 10, 3 26vAC, 25.5vAC, 35v AC, 0 (AWR-011 board).
Thanks.
tony
Feb 10, 2012, 3:26:37 PM2/10/12
to
On Feb 10, 1:52 pm, Jeff Urban <jurb6...@gmail.com> wrote:
> If there's no noise between stations with the muting off it's probably
> oscillating. That would maybe indicate filters or bypass caps. If the
> frequency actually drifts, assuming it has ONE fault which is usual,
> look around theFMoscillator or mixer stages.
> oscillating. That would maybe indicate filters or bypass caps. If the
> frequency actually drifts, assuming it has ONE fault which is usual,
>
> I think buzz between AM stations is just about normal these days,
> unless you specifically noticed a difference at the same time theFM
> fault showed up.
>
> Actually RF is not really my strong suit, but it's still electronics.
> If that reciever uses discrete transistors for theFM, it might be a
> I think buzz between AM stations is just about normal these days,
> unless you specifically noticed a difference at the same time theFM
> fault showed up.
>
> Actually RF is not really my strong suit, but it's still electronics.
> bit hard to find someone who really remembers how to work on it. That
> reciever is old enough for a pension, but by all means try to keep it
> alive.
>
> J
Thanks for the info.
> reciever is old enough for a pension, but by all means try to keep it
> alive.
>
> J
David Farber
Feb 10, 2012, 11:02:40 PM2/10/12
to
If you can hear the stations at all and they're randomly drifting try
squirting some tuner shower/contact cleaner into the tuning gang where the
rotating shaft contacts the bearings. There should be two or three bearings.
Then, move the tuning dial quickly from 88 to 108 back and forth several
times. You might have to spray several times to get the most benefit from
the cleaning. Did that help?
--
David Farber
Los Osos, CA
Tim Schwartz
Feb 13, 2012, 5:30:19 PM2/13/12
to
Have a look at the soldering on the regulator transistors on the power
supply board, and elsewhere. While its been a while since I've seen one
of these, I remember soldering on the pass transistors getting really
awful. Look for overheated, crystallized looking connections. if you
find some, desolder and re-solder them.
Regards,
Tim Schwartz
Bristol Electronics
tony
Feb 18, 2012, 9:13:33 AM2/18/12
to
On Feb 13, 5:30 pm, Tim Schwartz <t...@bristolnj.com> wrote:
> On 2/10/2012 8:15 AM, tony wrote:
>
> > Hi,
> > I have a Pioneersx-727. I'm the original owner over 40 years.
> On 2/10/2012 8:15 AM, tony wrote:
>
> > Hi,
> > Recently developedfmproblem.
> > Loud crackling sound onfmstation and then station drifts. No noise
> > at all between stations.
> > AM reception also not good, background buzz, humm between
> > stations on AM only. Unit works perfectly with CD and other inputs.
> > Any ideas what myproblemmight be? This all started a couple of weeks
> > AM reception also not good, background buzz, humm between
> > stations on AM only. Unit works perfectly with CD and other inputs.
> > ago,
> > when I noticed that signal strength meter was not illuminated, I
> > assumed just bulb burned out.
> > Tuning center meter still works. Any help would be appreciated.
> > Thanks.
>
> Tony,
>
> Have a look at the soldering on the regulator transistors on the power
> supply board, and elsewhere. While its been a while since I've seen one
> of these, I remember soldering on the pass transistors getting really
> awful. Look for overheated, crystallized looking connections. if you
> find some, desolder and re-solder them.
>
> Regards,
> Tim Schwartz
> Bristol Electronics
Thanks for the info. I'll look at soldering on the regulators.
> > when I noticed that signal strength meter was not illuminated, I
> > assumed just bulb burned out.
> > Tuning center meter still works. Any help would be appreciated.
> > Thanks.
>
> Tony,
>
> Have a look at the soldering on the regulator transistors on the power
> supply board, and elsewhere. While its been a while since I've seen one
> of these, I remember soldering on the pass transistors getting really
> awful. Look for overheated, crystallized looking connections. if you
> find some, desolder and re-solder them.
>
> Regards,
> Tim Schwartz
> Bristol Electronics
The outputs on the power supply board are withing spec but on the low
side.
AWR-011,
the schematic says
pin 2,5,6,7 12.5v, 30v, 30v, 36v
I'm measuring
pin 2,5,6,7 10.5v, 27.5v, 27.5v, 33v
However the collector of Q3 schematic says 36v, I measure ~20v.
pin 2,5,6,7 12.5v, 30v, 30v, 36v
I'm measuring
pin 2,5,6,7 10.5v, 27.5v, 27.5v, 33v
I'm not sure if that's a problem. This is on the power supply board
AWR-011.
Thanks.
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