Episode: 4222
Title: HPR4222: Replacing backup batteries in my Kenwood TS940S HF Radio Part 5
Source: https://hub.hackerpublicradio.org/ccdn.php?filename=/eps/hpr4222/hpr4222.mp3
Transcribed: 2025-10-25 21:36:38

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This is Hacker Public Radio Episode 4222 for Tuesday the 8th of October 2024.
Today's show is entitled Replacing Backup Batteries in My Kenwood DS940SHF Radio Part
5.
It is part of the series Ham Radio.
It is the 80th show of Mr. X.
And is about 16 minutes long.
It carries an explicit flag.
The summary is Part 5 deals with the removal of the original 40-year old PLL backup battery.
Hello and welcome Hacker Public Radio audience.
My name is Mr. X and welcome to this podcast.
As usual, I look to start by thanking the people HPR for making the service available to
us all.
Suleen and valuable service on these here in Tertubes.
HPR is a community that podcasts, provided by the community for the community.
That means you can contribute to it.
They are always looking out for shows and if we all send in just one show a year, they
have more shows than they do to do with.
HPR have gone to a great deal of effort to make the process very easy.
Just anything that can record, use it and send the show in.
Just go to that load page or give shows I think it is and send in your show.
There is also a set selection where you can see if you can't think of a topic.
There is suggested topics how you got into this, how you found HPR, what you are interested
or something like that.
Anyway, this episode is Part 5 on my continuing series of replacing batteries backup batteries
on my HF high frequency amateur Kenwood TS940S radio and this Part 5 in particular deals
with the removal of the original PLL backup battery.
PLL phase lock loop backup battery basically stores the frequencies and what not within
the radio.
This is the second battery that is being removed.
So sit back and enjoy.
Yeah, so yeah, Smotvis is starting and stopping the recording for this and I noticed
when I look back at the photographs, there is a prom and I see above the programmable
read only memory, is that what stands for?
Prom, it has got a label of it I think.
You add the programming and then the reason with a Zeltafile or something like that, I am
not sure.
Anyway, this prom has a label on it and it says Fe 84.
So that means around 1984, 1984, I am guessing the vintage of that prom anyway, so 86 wasn't
far out, but yes, so I was just downstairs and Missy's ex said to me, don't you fancy
glass of wine?
I'm not sure that's a good idea, but yes, oh why not.
So this next bit of the repair might be quite interesting.
Now, we're going to put the, yes, a battery.
So all I was going to do is check the voltage of the existing battery, so let me just
snap down stairs to the other, to the, and let me see, my DVM, my, yeah, trusty, flick
77, okay, black upstairs, and let's place that there and I'm guessing the volt battery
is going to be very low.
So just check, I'm going to place that there so I can see it.
Now 3.2 volts, that's surprising, that's surprising, wow, that battery is from 1984
and it's showing 3.2 volts, that's quite extraordinary.
I'm just going to set, oh yes, that's definitely acid, just give it a rubble of my finger, pretty
sure it is, aye, not a good idea, maybe not your finger of course, but it's not a good idea.
Yeah, I do see a better repair place that battery, it's a shame because it's still fine,
my voltage wise anyway, 3.2 volts, I can't get over that, I've got my test leads all,
caught up here in my head, I'm going to wash my hands now that I want to,
and the buttons on my hands somewhere, I said that I'll clean up the hicks in these things.
Look, aye, aye, aye, aye, aye, aye, aye, aye, aye, aye, aye, aye, aye, aye, aye, aye, aye, aye, aye, aye, aye, aye.
So, I'll just get the battery from the drawer here, the new battery, and check it against the old one
because I'm sure the pitch is going to be too small like before, yeah, I'm pretty sure it is.
Please sat there, oh yes, way too short.
I'm going to have to extend that.
Right.
So, I was having to think about the part of the problems I had soldering the battery last time.
I'm not quite sure why the standard terminal didn't solder terribly well, but the one I extended with a leg from my resistor.
The reason for that is probably because it's an old resistor and I should have, I should have, basically, from my training days,
you get along those pliers gently and pull them across the leads, and it basically scratches the coating off the lead
because it oxidizes over time and that will allow me to, the solder to stick properly to the lead.
So, that probably didn't help, so I shall do that this time and it should improve the solder ability.
You don't have to push hard, just grab gently in and pull across the lead, and that's nice and shiny now, that's good.
So, the solder should stick to that a lot better than the prior.
So, I've got the resistor, I've got the battery, I guess I should probably remove the old battery first, shouldn't I?
Because I'll do that, I'll lose all the memories and everything I bet when I do that.
I guess it's nothing else I can do about it really.
I was advised that lunch would be served at half past, so what's the time? 20 past, with 10 minutes.
Okay, okay, I've got my solder sponge and it's soaked with that.
Perfect, that's a perfect job for all the Christmas vehicles, you need peace and quiet to sort of do this.
And now I'm kind of breaking the job up into smaller chunks.
So, this is, can you get some solder?
Oh yes, that'll do nicely.
Oh, and I better plug my soldering iron in, but that might help me.
Plug my soldering iron in.
My trusty weller, bomb proof soldering iron.
John, and it's set to 330 degrees centigrade, no 304 degrees centigrade, 343 degrees centigrade.
Frick to read.
And I can't take the temperature, weller.
Alternate control, soldering iron, station EC2000.
That comes up pretty quick to temperature.
Move it from the stand, is that the temperature ready?
I'll just apply a little bit of heat.
I better get, I'll get my tweezers actually probably the best way to, if I can heat the joint and in once it's hot.
And it's soldered onto two posts basically.
I better put my tweezers.
Oh, they're up here on the bench.
Right, okay.
A bit of heat.
Apply a touch of solder to the tip.
Before the flux barons off, heat the post and lift.
And that's up.
Wow.
So it lifted, okay.
And then we're soldered.
And it's because the terminal has split where it's been riveted to the battery.
So I think that's that's the corrosionous cause that.
Yes.
Okay, so I'm going to have to gently
leave the battery stuck on to a foam pad.
Oh, crazy.
I'm not organised, where's my screwdriver?
I've lost a screwdriver.
Goodness sake.
Right, that's me being called and to pause at this point, turn my soldering off
and continue in a minute, a bit later on.
Okay, so that's me turned after my food and not feeling too tiggly after my glass of wine.
I should be able to continue.
So I need to peel this battery off the top of this I see into the circuit.
Yes.
And it's attached via a foam pad.
The look of it, but like the other battery.
I just took a sharp knife under it.
I can do that.
Maybe I can use, what else could I use?
No, I'm not trying that.
A bit of tweezers.
And the edge of it.
Oh, you're tearing noise.
I think the whole, I think the whole pad's coming off.
I prefer to keep because I could sit the back though.
Oh, no.
That's kind of tearing.
That's okay though.
Yes.
Okay, I think probably that might do.
I think if I heat that up, I'll be able to lift that.
So I'll just switch the soldering iron back on again.
And I think I might actually get my headband talked on.
So I get some light on the area.
I've got my glasses, I've got a headband talked on a headset.
It's a bit smudging.
Okay, that's fine.
Right, angle right on the light.
Okay, right.
That's my soldering at 200 degrees already.
250, 260, 270, 280, 290, 310, 20, 30, 40, 50, 60.
65, 70.
Yeah, there's obviously a bit of overshoot intellect here.
Yeah, it's cooling back down now.
3, 76, 98, 70.
Yeah, that's fine.
Okay, that's fine.
Plan a little bit of solder off to the soldering iron.
That's now at 340 degrees.
Just as it was said.
I can put it on.
Good, good.
Oh, good.
That's what.
Ah, right.
Okay, okay.
There's the battery.
Yes.
Yes.
I think it's what I'm looking for.
Hmm.
There we go.
Place that on that bag out of the way because I don't think I'm looking on my table or something
like that.
Yeah.
Okay, that was a wee bit of a abrupt ending there.
I said before, I chopped the audio into multiple sections because it was getting a bit long.
That concludes the removal of the second PLL phase lock loop battery in my Kenwood TS940S.
Beauty.
Do you need next time if you want to find out if the whole process was successful or not?
I think I actually about it for now.
If you want to contact me, if you have any comments or anything, you can contact me at MrX
at hpr at googlemail.com.
That's MRX80HPR, the at symbol googlemail.com.
So until next time, thank you and goodbye.
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