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TS-450s display problem

codecxbox

Member
Jul 28, 2021
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46
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I got this radio for a trade..
TX and RX are ok..
But it has a weird problem. the display overbrightens, lighting a bit segments that are not in use..its like the backlight is too strong..
is this like that or is there a way to correct this?
 

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AudioShockwav

Extraterrestrial
Staff member
Apr 6, 2005
7,355
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343
Sierras Near Yosemite National Park
I skimmed this off the net......

Quote:

It looks like you either have a bad 8VDC regulator or the inverter in the display has taken off and putting out higher voltage then it should.
The LCD A'SSY is detailed on page 159 of the service manual. It shows the 8VDC coming in on pin 2 and 5VDC on pin 1. Check these and make sure they are okay.
The regulators are located in the FINAL UNIT and there are two 8VDC regulators. The one you want is IC1 but check them all.
If the voltage is okay then you'll need to replace the LCD A'SSY Kenwood PN B38-0361-05. It could be difficult to find. You could try and repair the inverter on the LCD A'SSY but that stuff is tiny
End Quote.

Service manual can be found at the link below.
Scroll down to TS 450S/690S

http://www.wz5q.net/index/manuals.htm

73
Jeff
 

codecxbox

Member
Jul 28, 2021
86
46
18
thks! hmm this will be a tough one..kind of scared to crack it open lol..
Ill dl the service manual and lets see If its doable..
 

nomadradio

Analog Retentive
Apr 3, 2005
5,314
7,634
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Louisville, KY
www.nomadradio.com
Checking for missing or wrong power supply voltages is a basic troubleshooting step, especially for wacky faults like this.

Should not create too big a hazard to do that much. A failed electrolytic filter capacitor will frequently prove to be the cause.

One question that's worth asking is whether or not the radio has any of its marbles. Do the controls respond as if the computer is running? If spinning the tune knob doesn't change what you hear, that would be a bad sign. A failed display with a working computer can cause what you're seeing. A failed computer will not respond to front-panel controls.

73
 
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codecxbox

Member
Jul 28, 2021
86
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Checking for missing or wrong power supply voltages is a basic troubleshooting step, especially for wacky faults like this.

Should not create too big a hazard to do that much. A failed electrolytic filter capacitor will frequently prove to be the cause.

One question that's worth asking is whether or not the radio has any of its marbles. Do the controls respond as if the computer is running? If spinning the tune knob doesn't change what you hear, that would be a bad sign. A failed display with a working computer can cause what you're seeing. A failed computer will not respond to front-panel controls.

73
oh upto now, the VFO knob is working perfectly..all buttons are working too..so I guess the DSP is working ok..
I dealt with similar display problems with hifi recievers..the flourecent circuit is always a small 5 volt AC line tapped to the transformer..almost always that line goes 12 volts and thats a bad transformer..
but this radio..hmm how a flourecent display can light up properly with DC current
 

codecxbox

Member
Jul 28, 2021
86
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Nomad, heres a screenshot of the circuit..I cant find the PIN 1 and 2 where 8v and 2v are..I do see the tiny inverter and the CFL and usually thats a tiny AC line bulb..
 

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codecxbox

Member
Jul 28, 2021
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After studying the service manual, finally found connector 7 at the digital board..the connector supplies 8,5,14 volts and all are in spec..
So probably Im looking at a bad inverter..
would a LED strip work in place of the cathode tube?
 

codecxbox

Member
Jul 28, 2021
86
46
18
Caps, brown glue?
havent disassembled yet..the rabbit hole goes deeper..this radio has the internal autotuner..just for curiosity I followed the user manual procedure to autotune and I hear the gears turning for around 7 seconds and then a long intermitent beep..I guess its the warning alarm..on my meter with a dummy load, its only shows 2 watts at the most at 10 meters..also did the manual tuning procedure, same thing..
I swear I saw this radio doing 50 watts AM at the guys shack..so Im afraid Im looking at a bad PA stage too...or maybe its becuase Im using a 5 amp laptop brick ( which I use a lot for car radios, the short circuit shutdown is pretty good)..
Doesnt bother me much, was traded for 500 watt audio car amp..this RF stuff is getting out of hand lol
 

BJ radionut

Supporting Member and 6m addict
May 9, 2008
4,126
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35 miles East of Indianapolis
The TS-450sat needs like a 25 amp supply to properly test the transmitter section.
That 5 amp battery charger for a computer will never cut it. I would question that supply is regulated properly to even test the receiver, which will draw 2 amps (+/-) while in idle.
The tuner will never function correctly even with good regulation on a 5 amp supply. The rig will "tune" using like 20 watts carrier to "tune" + power to run the tuner.
I also wonder about the rig, 50 watts on AM mode is hot, 15-25 watts is max by Mfg. The rig will do 100 watts in CW/SSB mode but should never be set for 50 watts carrier in AM Mode.
I had one of those for like 11-12 years, great rig if it has not been abused. The main issue now is finding parts (some chips etc.) now that rig is close to 30+ years old.
GL
All the Best
Gary
 
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BJ radionut

Supporting Member and 6m addict
May 9, 2008
4,126
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35 miles East of Indianapolis
TS450 battery replacement (geocities.ws)

IF this mod was never done, I can pretty well guess why the display is not working correctly. Hope not!:(
The OEM battery, if left in holder passed the "leaking" stage have been known to EAT board traces due to acid from battery:mad:
I did this mod with-in a year of warrenty running out. Kenwood would do this to ANY TS-450 or TS-850 (remote the battery) that came thru service.

Picked up a used TS-450SAT~what problems should I look for? | QRZ Forums

TS-450S Problems (redwaveradio.com)

Jahnke Electronics – Kenwood Ham Radio Specialists
Due to a backlog of repair work, we are not taking further inbound radios at this time:(
 
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codecxbox

Member
Jul 28, 2021
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thks BJ..then Ill rig a car battery and a trickler..I do have a Tripplite 25 but its bad, loud sounding buzz and it cuts off, that buzz indicates bad transformer..i was thinking about using a 825 watt ATX PSU, but reading about using these psus for ham radio is not recommended
.
 

codecxbox

Member
Jul 28, 2021
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18
I was surprised this radio has a ATU..the model is a TS450S..it also has the SSB filter! that filters seems to be very rare and expensive, looking around the net..
 
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BJ radionut

Supporting Member and 6m addict
May 9, 2008
4,126
4,660
373
35 miles East of Indianapolis
The variety of the filter depends on what is installed. The're are numerous versions.
The're are Kenwood filters and INRAD filters, IMHO the later being better quality.
I had like 6 different filters installed in my TS-450.
6 kc AM filter
Cascade 2.4 kc SSB (extra 2.4/ one for each IF)(this board/filter is no longer available)
2.8 kc SSB
1.8 kc SSB
The INRAD filters I had installed, were actually in total worth more than the radio itself, when I sold it.
The Kenwood filters average about $75-100 each on used market.
The INRAD filters when you find them used are around $100 each
(some cost $150-$200 new)

International Radio ::... (inrad.net)

As you see from the list EACH RX/IF has a group of filters which can be installed.
My rig had a great receiver in it with the additional filters installed.
The adjacent channel rejection was excellent.
I sold that rig when I purchased my new Yaesu rig, maybe 10 years ago.
All the Best
Gary

PS: Many of the TS-450S rigs had tuner installed, though in the very early versions it was an option.

KENWOOD TS-450S HF TRANSCEIVER LEAKING CAPACITOR REPAIR | Flickr
 
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