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Kenwood TS-450 repair



 
 
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  #1  
Old September 21st 03, 10:22 PM
James
Guest
 
Posts: n/a
Default Kenwood TS-450 repair

I wish to repair my own Kenwood TS-450S-AT and to begin from
somewhere, I'd like to know what other 450's users think of the
current situation:

1) When I power the rig, I have no audio at all and no
trasmitting. The display shows a row of dots. If I move the
main dial, the frequency appears normally, but if I release it,
after half a second the dots appear again.

2) Some other times, when I give power I have both audio and
trasmitting and the display works well, but the audio in SSB/CW
modes is totally distorted, while it is ok in AM/FM modes.
However after 5-20 minutes of rx, the situation becomes that
described at point 1.

3) I have read of the battery problem in the 450, so I found
the lithium battery and measured it. It gives 3.28 V, is that
normal? Since the rig is approaching ten years I think I will
change it anyway, but I don't know if it is a problem now!

4) On the bottom side of the rig, near the place for the 455 kHz
cw filter (I have the 8.83 one, so this place is empty), there
is a 3-wire connector labeled "W3". The short cable, with a
similar connector on the other side, is attached to... nothing.
But I don't see any place to attach it, even if I look at the
whole board. Unfortunately I lack the 450/690 service manual
and I did not find this connector on the istruction manual
schemes. This MAY be normal, though.

My conclusions, for now:

a) When things are ok, except for SSB/CW, the problem should
arise in the second IF at 455 kHz. Either the CAR Unit does
not give a correct 455 kHz carrier or something is wrong in
the IF mixer chip or near it. In fact this chip is used only
in ssb/cw/fsk modes.

b) When the rig is almost dead, perhaps there is something wrong
in the digital/display unit. Lithium battery? Some digital chip,
which one?

c) Also the mere power could be a problem. My supply, 13.8 V 40 A
max, looks good, but internally there are circuits to obtain the
different voltages required and these could be damaged.


I am mainly looking for the service manual (someone has scanned
it?), but all other advices are welcome.

James



  #2  
Old September 22nd 03, 02:52 AM
Bob M.
Guest
 
Posts: n/a
Default

W3 connects to the TU-8 tone unit, which uses DIP switches to generate one
of about 40 PL or other tones. This would only be activated if you enabled
the front panel TONE switch, and probably would only be useful on FM.

My unit draws a solid 20 amps when transmitting, and if the power supply is
set to current limit at that point, it will do so. I'm using an Astron
VS-35M supply set to about 14v and full current, which should be good for 35
amps max, and have only had a problem when the current limit was set lower.
I doubt your power supply is a problem on receive, unless it's very low
(less than 8 volts) or very high (more than 18 volts).

The lithium battery should be used just for memory retention, and they're
normally around 3.6v, so 3.28 isn't too bad, but probably time to be
replaced anyway. My unit is 11 years old and I should look into the same
battery replacement in mine.

The rest of your symptoms are very strange. I can offer no help at all.
Obviously something is wrong, but I can't even begin to tell you what to
look for.

Bob M.
======
"James" wrote in message
...
I wish to repair my own Kenwood TS-450S-AT and to begin from
somewhere, I'd like to know what other 450's users think of the
current situation:

1) When I power the rig, I have no audio at all and no
trasmitting. The display shows a row of dots. If I move the
main dial, the frequency appears normally, but if I release it,
after half a second the dots appear again.

2) Some other times, when I give power I have both audio and
trasmitting and the display works well, but the audio in SSB/CW
modes is totally distorted, while it is ok in AM/FM modes.
However after 5-20 minutes of rx, the situation becomes that
described at point 1.

3) I have read of the battery problem in the 450, so I found
the lithium battery and measured it. It gives 3.28 V, is that
normal? Since the rig is approaching ten years I think I will
change it anyway, but I don't know if it is a problem now!

4) On the bottom side of the rig, near the place for the 455 kHz
cw filter (I have the 8.83 one, so this place is empty), there
is a 3-wire connector labeled "W3". The short cable, with a
similar connector on the other side, is attached to... nothing.
But I don't see any place to attach it, even if I look at the
whole board. Unfortunately I lack the 450/690 service manual
and I did not find this connector on the istruction manual
schemes. This MAY be normal, though.

My conclusions, for now:

a) When things are ok, except for SSB/CW, the problem should
arise in the second IF at 455 kHz. Either the CAR Unit does
not give a correct 455 kHz carrier or something is wrong in
the IF mixer chip or near it. In fact this chip is used only
in ssb/cw/fsk modes.

b) When the rig is almost dead, perhaps there is something wrong
in the digital/display unit. Lithium battery? Some digital chip,
which one?

c) Also the mere power could be a problem. My supply, 13.8 V 40 A
max, looks good, but internally there are circuits to obtain the
different voltages required and these could be damaged.


I am mainly looking for the service manual (someone has scanned
it?), but all other advices are welcome.

James





  #3  
Old September 22nd 03, 02:52 AM
Bob M.
Guest
 
Posts: n/a
Default

W3 connects to the TU-8 tone unit, which uses DIP switches to generate one
of about 40 PL or other tones. This would only be activated if you enabled
the front panel TONE switch, and probably would only be useful on FM.

My unit draws a solid 20 amps when transmitting, and if the power supply is
set to current limit at that point, it will do so. I'm using an Astron
VS-35M supply set to about 14v and full current, which should be good for 35
amps max, and have only had a problem when the current limit was set lower.
I doubt your power supply is a problem on receive, unless it's very low
(less than 8 volts) or very high (more than 18 volts).

The lithium battery should be used just for memory retention, and they're
normally around 3.6v, so 3.28 isn't too bad, but probably time to be
replaced anyway. My unit is 11 years old and I should look into the same
battery replacement in mine.

The rest of your symptoms are very strange. I can offer no help at all.
Obviously something is wrong, but I can't even begin to tell you what to
look for.

Bob M.
======
"James" wrote in message
...
I wish to repair my own Kenwood TS-450S-AT and to begin from
somewhere, I'd like to know what other 450's users think of the
current situation:

1) When I power the rig, I have no audio at all and no
trasmitting. The display shows a row of dots. If I move the
main dial, the frequency appears normally, but if I release it,
after half a second the dots appear again.

2) Some other times, when I give power I have both audio and
trasmitting and the display works well, but the audio in SSB/CW
modes is totally distorted, while it is ok in AM/FM modes.
However after 5-20 minutes of rx, the situation becomes that
described at point 1.

3) I have read of the battery problem in the 450, so I found
the lithium battery and measured it. It gives 3.28 V, is that
normal? Since the rig is approaching ten years I think I will
change it anyway, but I don't know if it is a problem now!

4) On the bottom side of the rig, near the place for the 455 kHz
cw filter (I have the 8.83 one, so this place is empty), there
is a 3-wire connector labeled "W3". The short cable, with a
similar connector on the other side, is attached to... nothing.
But I don't see any place to attach it, even if I look at the
whole board. Unfortunately I lack the 450/690 service manual
and I did not find this connector on the istruction manual
schemes. This MAY be normal, though.

My conclusions, for now:

a) When things are ok, except for SSB/CW, the problem should
arise in the second IF at 455 kHz. Either the CAR Unit does
not give a correct 455 kHz carrier or something is wrong in
the IF mixer chip or near it. In fact this chip is used only
in ssb/cw/fsk modes.

b) When the rig is almost dead, perhaps there is something wrong
in the digital/display unit. Lithium battery? Some digital chip,
which one?

c) Also the mere power could be a problem. My supply, 13.8 V 40 A
max, looks good, but internally there are circuits to obtain the
different voltages required and these could be damaged.


I am mainly looking for the service manual (someone has scanned
it?), but all other advices are welcome.

James





  #4  
Old September 22nd 03, 03:37 AM
Hank Oredson
Guest
 
Posts: n/a
Default

One simple thing to try: loosen and retighten all screws that
hold down circuit boards; wiggle all jumper connectors, so
they are reseated and the contacts wiped a bit. This cured
several really strange problems on my very old TS-930.

--

... Hank

Hank: http://horedson.home.att.net
W0RLI: http://w0rli.home.att.net

"James" wrote in message
...
I wish to repair my own Kenwood TS-450S-AT and to begin from
somewhere, I'd like to know what other 450's users think of the
current situation:

1) When I power the rig, I have no audio at all and no
trasmitting. The display shows a row of dots. If I move the
main dial, the frequency appears normally, but if I release it,
after half a second the dots appear again.

2) Some other times, when I give power I have both audio and
trasmitting and the display works well, but the audio in SSB/CW
modes is totally distorted, while it is ok in AM/FM modes.
However after 5-20 minutes of rx, the situation becomes that
described at point 1.

3) I have read of the battery problem in the 450, so I found
the lithium battery and measured it. It gives 3.28 V, is that
normal? Since the rig is approaching ten years I think I will
change it anyway, but I don't know if it is a problem now!

4) On the bottom side of the rig, near the place for the 455 kHz
cw filter (I have the 8.83 one, so this place is empty), there
is a 3-wire connector labeled "W3". The short cable, with a
similar connector on the other side, is attached to... nothing.
But I don't see any place to attach it, even if I look at the
whole board. Unfortunately I lack the 450/690 service manual
and I did not find this connector on the istruction manual
schemes. This MAY be normal, though.

My conclusions, for now:

a) When things are ok, except for SSB/CW, the problem should
arise in the second IF at 455 kHz. Either the CAR Unit does
not give a correct 455 kHz carrier or something is wrong in
the IF mixer chip or near it. In fact this chip is used only
in ssb/cw/fsk modes.

b) When the rig is almost dead, perhaps there is something wrong
in the digital/display unit. Lithium battery? Some digital chip,
which one?

c) Also the mere power could be a problem. My supply, 13.8 V 40 A
max, looks good, but internally there are circuits to obtain the
different voltages required and these could be damaged.


I am mainly looking for the service manual (someone has scanned
it?), but all other advices are welcome.

James





  #5  
Old September 22nd 03, 03:37 AM
Hank Oredson
Guest
 
Posts: n/a
Default

One simple thing to try: loosen and retighten all screws that
hold down circuit boards; wiggle all jumper connectors, so
they are reseated and the contacts wiped a bit. This cured
several really strange problems on my very old TS-930.

--

... Hank

Hank: http://horedson.home.att.net
W0RLI: http://w0rli.home.att.net

"James" wrote in message
...
I wish to repair my own Kenwood TS-450S-AT and to begin from
somewhere, I'd like to know what other 450's users think of the
current situation:

1) When I power the rig, I have no audio at all and no
trasmitting. The display shows a row of dots. If I move the
main dial, the frequency appears normally, but if I release it,
after half a second the dots appear again.

2) Some other times, when I give power I have both audio and
trasmitting and the display works well, but the audio in SSB/CW
modes is totally distorted, while it is ok in AM/FM modes.
However after 5-20 minutes of rx, the situation becomes that
described at point 1.

3) I have read of the battery problem in the 450, so I found
the lithium battery and measured it. It gives 3.28 V, is that
normal? Since the rig is approaching ten years I think I will
change it anyway, but I don't know if it is a problem now!

4) On the bottom side of the rig, near the place for the 455 kHz
cw filter (I have the 8.83 one, so this place is empty), there
is a 3-wire connector labeled "W3". The short cable, with a
similar connector on the other side, is attached to... nothing.
But I don't see any place to attach it, even if I look at the
whole board. Unfortunately I lack the 450/690 service manual
and I did not find this connector on the istruction manual
schemes. This MAY be normal, though.

My conclusions, for now:

a) When things are ok, except for SSB/CW, the problem should
arise in the second IF at 455 kHz. Either the CAR Unit does
not give a correct 455 kHz carrier or something is wrong in
the IF mixer chip or near it. In fact this chip is used only
in ssb/cw/fsk modes.

b) When the rig is almost dead, perhaps there is something wrong
in the digital/display unit. Lithium battery? Some digital chip,
which one?

c) Also the mere power could be a problem. My supply, 13.8 V 40 A
max, looks good, but internally there are circuits to obtain the
different voltages required and these could be damaged.


I am mainly looking for the service manual (someone has scanned
it?), but all other advices are welcome.

James





  #6  
Old September 22nd 03, 12:46 PM
Geoffrey S. Mendelson
Guest
 
Posts: n/a
Default

In article , Bob M. wrote:

The rest of your symptoms are very strange. I can offer no help at all.
Obviously something is wrong, but I can't even begin to tell you what to
look for.


They are very common. Kenwood potted the main PLL in a rubber compound
to isolate from thermal changes and mechanical shock. In plain English to
slow down the effect of temperature changes and prevent frequency jumping
if you tapped the radio, or when mobile went over a bump.

The problem is that over the years the rubber compound started to absorb
water from the air. If you were in a totaly dry enviornment this would
never happen. I have an R5000 (same problem). When I lived in the U.S. I
kept the radio in a basement that was so wet everything would rot in a
few days, so we kept a dehumidifier running and the basement was very
dry. The radio never had a problem.

After sitting in a box and then a freight container over the ocean, it
picked up enough moisture to fail in about 3 months.

The fix is simple in theory and is documented on the Kenwood web site.
You remove the shield from the main PLL, remove the rubber compound,
replace any parts damaged due to corrosion and readjust the PLL.

An experienced technician, such as Cliff at AAVID, can do it for
about $100 for parts and labor. Unless you have the correct tools
and equipment, I'm not sure you can do it, but many people have.

Geoff.

--
Geoffrey S. Mendelson 972-54-608-069
Icq/AIM Uin: 2661079 MSN IM:
(Not for email)
Carp are bottom feeders, koi are too, and not surprisingly are ferrets.

  #7  
Old September 22nd 03, 12:46 PM
Geoffrey S. Mendelson
Guest
 
Posts: n/a
Default

In article , Bob M. wrote:

The rest of your symptoms are very strange. I can offer no help at all.
Obviously something is wrong, but I can't even begin to tell you what to
look for.


They are very common. Kenwood potted the main PLL in a rubber compound
to isolate from thermal changes and mechanical shock. In plain English to
slow down the effect of temperature changes and prevent frequency jumping
if you tapped the radio, or when mobile went over a bump.

The problem is that over the years the rubber compound started to absorb
water from the air. If you were in a totaly dry enviornment this would
never happen. I have an R5000 (same problem). When I lived in the U.S. I
kept the radio in a basement that was so wet everything would rot in a
few days, so we kept a dehumidifier running and the basement was very
dry. The radio never had a problem.

After sitting in a box and then a freight container over the ocean, it
picked up enough moisture to fail in about 3 months.

The fix is simple in theory and is documented on the Kenwood web site.
You remove the shield from the main PLL, remove the rubber compound,
replace any parts damaged due to corrosion and readjust the PLL.

An experienced technician, such as Cliff at AAVID, can do it for
about $100 for parts and labor. Unless you have the correct tools
and equipment, I'm not sure you can do it, but many people have.

Geoff.

--
Geoffrey S. Mendelson 972-54-608-069
Icq/AIM Uin: 2661079 MSN IM:
(Not for email)
Carp are bottom feeders, koi are too, and not surprisingly are ferrets.

  #8  
Old September 22nd 03, 03:23 PM
MD
Guest
 
Posts: n/a
Default


"Geoffrey S. Mendelson" wrote in message
...
In article , Bob M. wrote:

The rest of your symptoms are very strange. I can offer no help at all.
Obviously something is wrong, but I can't even begin to tell you what to
look for.


They are very common. Kenwood potted the main PLL in a rubber compound
to isolate from thermal changes and mechanical shock. In plain English to
slow down the effect of temperature changes and prevent frequency jumping
if you tapped the radio, or when mobile went over a bump.

The TS450's do NOT use the compund that caused so many problems in the
TS440's. I have owned both.

The fix is simple in theory and is documented on the Kenwood web site.
You remove the shield from the main PLL, remove the rubber compound,
replace any parts damaged due to corrosion and readjust the PLL.

AS I said there is no compound in the 450.


If you are experiencing a row of dots on your display, this is a sign your
VCO is out of lock. If you can borrow a service manual, it is very easy to
realign.


  #9  
Old September 22nd 03, 03:23 PM
MD
Guest
 
Posts: n/a
Default


"Geoffrey S. Mendelson" wrote in message
...
In article , Bob M. wrote:

The rest of your symptoms are very strange. I can offer no help at all.
Obviously something is wrong, but I can't even begin to tell you what to
look for.


They are very common. Kenwood potted the main PLL in a rubber compound
to isolate from thermal changes and mechanical shock. In plain English to
slow down the effect of temperature changes and prevent frequency jumping
if you tapped the radio, or when mobile went over a bump.

The TS450's do NOT use the compund that caused so many problems in the
TS440's. I have owned both.

The fix is simple in theory and is documented on the Kenwood web site.
You remove the shield from the main PLL, remove the rubber compound,
replace any parts damaged due to corrosion and readjust the PLL.

AS I said there is no compound in the 450.


If you are experiencing a row of dots on your display, this is a sign your
VCO is out of lock. If you can borrow a service manual, it is very easy to
realign.


 




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