Tuesday, July 05, 2011

Part II - Replacing and Relocating The Battery In A Kenwood TM-331 (TM-241, TM-441, Etc.


I’ll type up the notes for this over the next few days.

I’m on Steve-Time…  W4HKL.

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Remove the plastic cover on the battery.

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This is the side we’ll pry up first.

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The polarity is as follows:

Top battery lead : Negative

Bottom lead: Positive.  You might want to pencil this in on the board somewhere to remind yourself later.


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Let’s get this show on the road…

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Use your fingers and the screwdriver…  get it up far enough to get some angle cutters in.

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Press the lower insulating pad back down if you can.

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Yes, the bottom of the battery is the positive side.

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I wondered why the TM-331 would retain memories most of the time yet sometimes lose them.

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0.15 Volts…  it should be around 3.0 Volts.

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Time to prep the batter holder, etc.

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This is more like it… and more likely to retain memory.

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Making sure the battery will be insulated from everything.





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Don’t tin these leads or you won’t be able to wind them around the battery holder terminals.  After winding, I bend the pins down a little to reduce the footprint of the holder.  This will have to fit inside the radio…

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I tinned the ends here before crimping them inside the old battery tabs coming from the board.


Soldering to the crimped ends lends a lot more mechanical strength to the connection as well as a good electrical connection…

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After you’ve heated the crimp… and also flowed a little more solder on the end of the tinned ends of the wire and up into the crimp…  test your voltage on the board.  It should be 3+ volts.

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Now tape it all up.

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Battery too…

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Note that I bent the wire well away from the solder joint in order to get the cord going in the right direction.

Congratulations!  You’re 10-20 minutes from being finished…

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Work backward…  and be careful.  Don’t get in a hurry.

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Routing the cables back into the RF section of the radio.

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Don’t forget this green wire loop.

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Again, I was lucky – the buttons were staying in place.  If you’re are “squirrelly,” you may have to keep the faceplate tilted and bring the radio up to meet it.


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Press all the button pads… make sure none are in a bind before proceeding.

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You can tell if one’s stuck, etc..

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Click… click…


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Now for this little SOB…  all I can say is take your time, work a little from one side and then the other… 

and hold your mouth right.


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Time to power up, enter a frequency, and give it a whirl.

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Powering down, cutting off the power supply, and then seeing if the memory is retained.

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Time for the moment of truth… will it work?



1 comment:

AI4WM said...

Very well done. I've done similar with my TM-231 and I am about to to the same with my TM-241. There is just enough space to place the battery and holder in a small plastic enclosure in the radio. I have mine along with the optional tone board in a tic-tac mint box. A small sheet of Kapton insulates them.