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Old September 22nd 03, 02:52 AM
Bob M.
 
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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