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.

Remove the plastic cover on the battery.

This is the side we’ll pry up first.

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.

 

Let’s get this show on the road…

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

Press the lower insulating pad back down if you can.

 

 

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

 

 

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

0.15 Volts…  it should be around 3.0 Volts.

Time to prep the batter holder, etc.

 

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

Making sure the battery will be insulated from everything.

 

 

 

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…

 

Soldered…

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…

 

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.

Now tape it all up.

Battery too…

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…

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

 

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

Don’t forget this green wire loop.

 

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.

 

 

 

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

You can tell if one’s stuck, etc..

Click… click…

 

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.

 

 

 

 

 

 

 

 

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

 

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

 

 

Success!

 

 

Time for the moment of truth… will it work?

 

- W4HKL

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

 

No write-up yet…  just pictures.

Will type up notes over the next few days.

- Steve, W4HKL

 

Here’s a look at what’s needed to perform the battery swap and relocation.

 

 

 

The most important component for protracted work of any kind.

The Kenwood TM-330 220 Mhz rig.

The following 4 screws need to be removed.

 

Flip it over and remove the 4 on the bottom cover.

 

 

I’m pointing to the areas you need to gently tug on to remove the covers.

 

 

Once you get it tilted up you can pull it free. Note the tabs.  You will have to do this process in reverse at the end of the batter swap/replace.

 

Flipping it back to repeat the process on top.

 

The top removed.

I’m glad someone on the design team designed a nice, long speaker wire.

Remove the battery mount.

This is the connector for the optional CTCSS decoder.  Note how it is routed into the faceplate area as the battery lead will be placed beside it.

Now the hard part.  Once the knobs are pulled loose you will have to CAREFULLY lift these up and gently slide the black plastic faceplate cover off.

Did I mention they’re brittle and extremely annoying as they have a nasty habit of snapping back on as you try to slide the next one off?

 

Poweraid caps make a nice place to store various parts.

Little buggers…

This part took about 10 minutes.

Finally!

Keep working it back and forth until its off.

We need to remove this part of the faceplate to get to the battery.  Be careful of the buttons.  I was lucky with this radio.  I screwed up with a TM-731 and allowed all the buttons to fall of.  Imagine spilling a box of chicklets onto your desk and carpet – several times.

Fortunately the retaining nut on the mic plug was removable with these forceps.

 

And the other nut…

Easy does it…

But wait, there’s more!!!

Remove the metal covering…  6 or so screws spread around the top, bottom, and sides.

Okay, this it it the brains of the unit.  Use an anti-static wrist strap… or just make sure you touch something grounded every so often as a precaution.

On a positive note, the TM-241, 441, etc, are a LOT easier to get into than this.  In fact, after doing the 241 and 441, I kept thinking “what’s next” with the 331.

3 screws need to be removed.  They are pointed out here.

 

The last step to removing the CPU board is sliding it off the connectors pointed out here.  You have to be careful.  It won’t just slide loose.  Use your fingers and work each side back and forth until you see the gap form between the two sides of the connectors.

 

There is goes…

Whew…

Note that only the ends of this board are supported when placed like this.  Be careful not to press down hard in the middle and flex the circuit board. 

 

Continued in Part II…

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http://www.arrg.us/pages/WB3AYW/VHF-duplexer.htm

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