Episode: 4232
Title: HPR4232: Replacing backup batteries in my Kenwood TS940S HF Radio Part 6
Source: https://hub.hackerpublicradio.org/ccdn.php?filename=/eps/hpr4232/hpr4232.mp3
Transcribed: 2025-10-25 21:47:34

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This is Hacker Public Radio Episode 4232 for Tuesday the 22nd of October 2024.
Today's show is entitled Replacing Backup Batteries in My Kenwood DS940SHF Radio Part 6.
It is part of the series' Ham Radio. It is hosted by Mr. X and is about 22 minutes long.
It carries an explicit flag. The summary is, Part 6 is the final episode of deals with fitting the new replacement PLL backup battery.
Hello and welcome Hacker public radio audience. My name is Mr. X and welcome to this podcast.
As usual, I would like to start by thanking the people HPR for making this service available to us all.
HPR has an invaluable service on these heritage tubes.
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Using a phone, MP3 plate, you have got one tablet, PC, laptop, whatever. Anyway, this episode is Part 6 of my series on replacing backup batteries in my aging amateur radio set.
My aging can with TS940S amateur radio set. This Part 6 consists of fitting the battery on the previous episode.
The previous episode I removed the old backup battery on the PLL board. This episode I am going to fit the new battery into PLL board.
We will see how it goes from there. I will just take it from there.
Now whether to put the new battery, here it is.
Just check how these pillars look reasonably clean. That will be OK.
Positive is on the left hand side, negative is on the right.
I need to prepare the battery by attaching the battery.
I have actually got a blue wire, I could link it with that I suppose, but then it will be supported on one side.
I think I will just do the same with the last time and attach a resistor leg to it and then bend that into place.
That seemed to work quite well, so I will do the same again.
I should just check. This is in the wrong order because I should check the battery voltage of the new battery.
I did not check the old battery, which unbelievably after about 40 years we are still showing 3.5 volts.
Quite astounding, yeah 3.35 volts and the new one 3.35.
Was it 3.5? It was 3.3 as well, I can't remember.
I am sure it was 3.3 actually.
Right, so the plus, which side is the plus?
Not sure. Oh yes, the plus is in the top, in this case.
That would be that way plus, right.
I need to take this resistor and I will leave it at that.
It is basically a normal carbon resistor basically.
I am just going to bend that hook on the end of it with a pair of pliers.
Then fit that to place that through the whole of the terminal on the battery.
That is that on there.
Then I need to use a pair to squeeze it, shut the hook so that it stays in place.
That is that. That is good. That is okay.
That is fine to want to do now, solder that in place now.
We can sit it on the plastic of my glass I suppose.
Do they do with helping hands or something like that to hold it in place?
Balance it over the edge of the desk and wonder, that is not great.
A pair of pliers on that will do.
That will do nicely.
Remember I scraped the end of the lead for the resistor so it will solder properly.
I could have tinned it first but then it makes more difficult to bend it into place.
I decided to do that.
I am just applying some solder.
Do we touch more solder?
I am going to find this solder.
That might be okay.
I will check.
Where is my eyeglass?
Oh yes, that is a good joint.
I will bend this up.
I will just see before I bend it up.
Is that a photo key?
Oh yes.
Do I bend this up or do I leave it as it is?
I think that might be okay as it is.
I think I might leave that.
I will take a photograph so you can see what I have done with the resistor and the battery.
I will show you it in place.
I will just pause this now.
I think I shall just place that onto the pin on the pin.
I think that is going to work fine.
That is looking good.
Now that that is in place, I am going to solder that in place.
That is 1 and that is plus, definitely plus to the correct side plus.
I will just apply a little bit of solder.
I am not sure I am liking this.
I swapped a bit of solder.
I have got various pieces of solder.
I am not sure I like this fine stuff.
It is so fine that you need to apply a lot more than you normally would to fill the joint.
I am going to use my eye glass because I cannot see what I am doing.
I think I will just pause this and do this without the well recording because it is a bit
fiddly.
That is the battery soldered in place.
I am not terribly happy with the connection on the right hand side.
I think I have a problem getting the solder to flow properly around the connections on
the first battery actually.
Strangely, the certainly scraping the resistor on the resistor before fitting it to the battery
has been a huge difference and the solder has flowed around that nicely.
Also onto the post.
I could have cut the lead a bit shorter but I did not have enough lot of room to spare
and I did not want to leave it too short and you cannot add a bit more when you take too
much off.
There is no harm in it being a bit too long on the left hand side.
You will see from the picture a bit the right hand side.
There is actually, if you look closely you can actually see a gap with the solder
so there is no flowed properly around.
The battery does seem to be securely attached to the right hand side even although the solder
ring is not fantastic, it will be okay.
There is not going to be, you know, transport that down, roads or anything like that.
It is going to be sitting in this room not moving so it should be fine.
I am going to leave that as it is.
I am a bit scared that I will overheat something or damseling it.
It is attached, that is the main thing.
It is just a matter of putting everything back together again I think you really know.
I need to get the top cover back onto this metal plate back on again and it was quite interesting
because I did not think I would be able to get that off with just six connections off but
you know, the tapping video was absolutely right.
You can do it by just removing the six connectors and leaving the other ones be up and to watch
this underneath and not catching any cables.
It needs to go up and over, doesn't it?
Yeah, okay.
This could be a bit fiddly.
Okay.
Mm-hmm.
Okay, is that it is close.
I should just drop into this.
That does not feel right somehow.
They do not trap any wires.
That is the other thing I have caught.
Oh yeah, there is wires everywhere.
Crikey.
You said to watch not to trap wires on the front part.
I would say this is worse.
I do not have any problems with the front being trapped.
It is more this metal can.
I think.
All right.
Is that it?
And please.
Mm-hmm.
Maybe.
I think I am going to look all the way around and make sure there is no connections trapped.
That looks okay.
On the side does that look all right?
Yep.
That looks okay.
What a bit on the front face.
It is in and caught.
Yeah.
That is not in place actually.
Goodness.
I thought it was.
That is not quite right yet.
Mm.
Okay.
That is not right.
There is something not right.
Yes.
There is cables.
Okay.
That is all right there.
Try that.
Is that it?
Ah.
There we go.
No.
Something not right.
Definitely not.
Why is that not?
Mm.
This is a bit worrying.
I do not see anything trapped.
That is something properly on the base there.
Yes it is.
So, I should be able to get the other side on that case.
Is it here?
Is it the front?
Something is different.
Not right.
Yeah.
I am going to have another wee look at this.
Mm.
It feels like it is rocking as if something is caught jammed underneath.
I am going to have another closer look at this to stop recording.
I have another wee look.
Okay.
So, it turns out there is a lip on the far end of the box and it was catching that.
There is nothing more than that.
I just squeezed the box in slightly and in the middle at the rear and it just dropped into
place.
That is all it was.
It was just slightly catching as I was pushing it down.
I was just a bit really quick.
Worried that I was catching a wire or something like that and trapping it.
That would be disaster because you would get quite sharp edges on that middle box and it
would have sheared the thing.
That is one screw in and I am going to try and put the screws in and kind of diagonally
opposite one another.
A kind of colleague telling me that is how you should fit screws.
I think he experiences of working on cars and stuff.
You don't distort the item of screwing it down onto.
I have no experience of that.
I think I have two spare plugwits as far as I can go.
Your filter.
Stuff like that.
That is three screws in for screws.
For the top lid.
Top silver lid.
Five screws.
Because I am doing all the easy ones, I am just putting them in loose.
One, two, three, four, five.
Six.
I definitely don't want to.
Drop a screw into the radio at six.
Seven.
I can manage that without dropping it.
I think so.
Fiddly this one.
Seven.
There is wires going to be here to work careful.
I don't nip any of them.
I can light this.
Room is horrendous.
I can put my head over the radio and then suddenly it all goes dark.
Seven.
And then the last screw.
Eight.
So that wasn't so bad at all.
I think breaking the job down helps.
If you have got the luxury of leaving the job.
Or you have got the luxury of having the whole day to work on something.
Or you have got the room just to leave your tools and stuff lying about the place then.
On your bench, whatever.
That is fine, but I don't have the space and the luxury for that.
So one.
That is all now.
One.
I'll just give them a tighten up.
Two.
Three.
Four.
Five.
Oh.
Wait a minute.
Oh no.
Okay.
Six.
Seven.
Eight.
I'm just going to go through any more looking because I'm asked one.
One.
Two.
Three.
Four.
Five.
Six.
Seven.
Eight.
They're all tight.
That's good.
Not too tight.
Not too tight enough.
Right.
So I was thinking that the connectors, I can't get the connectors back onto the side of the
unit, but then I realised that the connectors got attached to the speaker, not to the speaker
unit, not the silver box.
So that's fine.
Okay.
The speaker, rotate it back and just into place.
Now.
How does that go?
As you're taking, as you looked at my photographs before, how does that fit?
That's a bit tight for speech.
I should have paid more attention to this when I was taking it out.
I think again, I'll pause the recording and get this fitted and then come back because
this is just a bit boring.
I can concentrate on what I'm doing here.
So that was quite interesting.
I was trying to get the speaker back into position.
I know it's something underneath and somebody had soldered a couple of old wires onto the
speaker and then just cut them off and put a bit of tape on them.
So yeah.
There's obviously been a few, there's opened a few times and I couldn't know why they'd
have two speakers wires attached.
There's all kinds of outputs on the back of the radio to get audio from the radio.
I'm not quite sure why they did that, but interesting nonetheless.
I actually removed them anyway in that.
So we don't want that to short out or to go wrong at some point.
So it just took two minutes.
So that's the all the circuits back in place and the speaker back in place.
I thought I might have to use my old trick with them.
Blue tack or a equivalent type thing to stick on into the screwdriver.
It's a chewing gummies type stuff.
You can put your screw on on then they are screwed over and hold it in place where I'm trying to get down a deep recess
because the screws are a bit difficult to get in.
I've got a kind of magnetic screwdriver that I was able to do with that.
So that's that.
Now, probably having the screws I've got left to do.
Yes, I've only got the case screws defect.
I think what I'll maybe do is I'll fit the top, just place the top cover up or just make sure everything's having looks okay all the things are in place.
That's fine, that's the wrong there.
The border of the missing screw, I've just noticed that it's not even screwed down properly.
Let's say the screws are all loose.
Can I take them up further?
No, I don't know.
Yeah, I'm going to leave that alone.
I want to do the minimum amount of modifications to this you're doing because I break something.
So I don't think the screws will go down any further.
So whether they're not the right screws or something's not right, but they're that.
It's to secure anybody, so that's the main thing.
I'll leave the border alone.
Put the cover on.
And I mainly push the AB key while powering it on.
Because the PLL will have lost all its settings and whatnot and it might get a bit confused.
We'll see.
Oh, of course, there's a ton.
I've mentioned that, there's a ton, I think I have.
Oh, she was.
Right, that's that.
Make sure it's turned off, it is.
And we'll put the mains lid in.
I'll just put that antenna in just in case it goes into task.
I'm just stupid like that.
It shouldn't, just in case.
It means that there's a load in the antenna.
And it won't damage the outputs.
Yeah, that's because I'm quite delicate.
Right, three, two, one.
Well, all seems okay.
7.1642.
So there we go, that's fucking fine.
Wow, I can't believe it, good, good.
So I'll let you move it again and put screws in and what the final screws in.
Put it on properly.
So there you go, that's fucking fine.
Wow, I can't believe it, good, good.
So I'll let you move it again and put screws in and what the final screws in.
It's on properly.
But I won't bore you with all that.
I think it's probably enough.
These are going to be long enough as it is.
I'm not sure whether I'm going to have to split them up because they're going to be too long with the recordings.
But I hope you've got something out of it.
If nothing else, you hear this.
When you don't properly prepare, you don't have the space, you don't have the time.
How things can quickly go wrong.
And that doesn't damage anything, we're just working.
And hopefully I've saved it from almost certain death by corrosion from an internal battery.
I can't believe that, a 40-year-old battery, and it's still operational, if leaky.
So yeah, I think that's all I've got for you just now.
So thank you very much.
Or so I thought anyway.
However, later on after they put the covers back on the radio and turned it on.
And I thought, it was maybe actually a day or so later I thought, that sounds a little quiet.
Why is the fan not coming on?
So there's a fan.
I think that might actually be two fans.
There's certainly one fan anyway.
And normally, under normal circumstances, if you put the radio on every few minutes,
this fan comes on gently and goes off again, it cycles off and on.
And I'm not entirely, I haven't seen great detail.
But it's not, I don't think it's for the PA, you know, the power output stages.
Although maybe a fan for that separate, I'm not sure.
I think it's just for the power supply section.
And anyway, it's not, it's no longer switching off and on.
So it looks like something has happened and it's mysterious that it happened after I pulled the radio up.
So I'm guessing I've done something, broken something.
So I've maybe trapped a wire or something like that.
So obviously, further investigation will be required.
So when I got a chance, I can turn it on for five or ten minutes or so,
but then it starts to get a bit warm at the back.
And I wouldn't want to damage anything.
So that's a bit unfortunate.
It's actually worse than when I first started.
So that's good.
There's always a risk that can happen.
Of course, never you take something to bits.
The more complex it is, the more likely are to damage it, I suppose.
But I haven't given up all hope by any means.
I'm going to have another look at it at some point when I get a chance.
Maybe we'll be next Christmas when I get a chance to get a bit of spare time.
I don't know.
But anyway, I think that's about it for this episode.
In this series, and I hope you all enjoyed it.
And I'll catch you later.
If you've got any comments, you can contact me at MrX,
at hpr at googlemail.com.
That's MRX, AT, HPR,
the at symbol googlemail.com.
So until next time, thank you and goodbye.
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