Hi in the previous video which I'll link in down below and at the end if you haven't seen it. We took a look at this Australian made sister on Donna from the early 70s. It's a timer counter slash frequency counter, but it's not just a frequency counter. Timer counters do more any way that we looked at the tear down of this and also trying to calibrate the internal oscillator.

It has two oscillators inside it. One is like just a, you know, a crusty quartz crystal on the main board inside. You know it's not temperature compensated anything like that, so you know it's going to be like in the order of like ppm, stability, a few ppm, something like that. Not great, probably back then.

Yeah, we're talking like tens of ppm perhaps. but in the back it does actually have an urbanized crystal oscillator, which of course is fantastic in which were you want. But unfortunately when I was tweaking the thing at the back, it's got an adjustment pot to tweak that oscillator I couldn't get it working and I thought that I was mucking it like using this thing wrong or anything, but it wasn't I think there's actually something wrong with it. so I thought we'd get our Agilent our frequency counter here.

I've done a couple of videos on this which are also linked in how you can actually use a frequency counter as a gravity detector which is a fantastic video. Highly recommend you check that out. and I also did a organized oscillator upgrade on this thing too I think Anyway, I've now got this hooked up to the output of the oven IIST oscillator on the back here. so we're getting you know, somewhat over the nominal 10 megahertz.

so let me just go and adjust that and see if we can actually make a difference. So trust me, I've got my tongue at the right angle and I'm 12 on that and she ain't budging. So I can take it all the way. That's like a 10 turn pot, 5 or 10 turn pot in there and I can take it like oh I just felt it go to the extreme end there and I can go to the extreme end on the other way and it doesn't do and it doesn't do diddly squat.

so obviously there's something wrong. Has that pot? you know, broken age? There we go. I've gone extreme end the other way. We can't adjust that you'd expect.

you know, at least like a maybe a fifty or a hundred Hertz either side of that ten megahertz adjustment range there and we just not get in it so thought we'd crack it open have a look so there's the puppy down in there. we'll see if we can extract that out. I Don't know, like what brand or anything is really hard to read that to her. green on on the nickel finish or whatever it is.

so let's try. No. I don't know how to get that out. It's gonna be strapped on there something like that and they all this cabling.

Yeah. Anyway, hopefully it's not like a soldered shut or anything like that. That'll be a pain. so it looks like we have to get in there.

Here it is up. there's a couple of a couple of screws if we take those out, maybe it should pop out and we can get access to the strap, the nuts of which are on the bottom side there. so let's give that a ball. Wow This is actually the first time I've noticed like a fan instrument fan getting quite warm, the hub on the back of that, um, it stick.

Trust me, that's like it's ridiculous. Like I didn't haven't run in that long to shoot the intro to this video. Crazy. So there's our module monitored PC from Pasadena California Hmm.

Interesting. So there you go. The oven art runs at 115 volts AC and so it must get that off a a tap on the transformer because this is a 240 volt unit serial number for those playing along at home. and there's the adjustment pot in the back which you can see the thread like it goes on.

you know if air travel in and out there. but I'm getting diddly-squat on that so let's try it out. Hopefully we can open this up. so I think I have two like they've got like a socket on the back of this thing.

So I think I've got a prize it prize it out of the socket there gently. Tada yeah, that beautiful thing of beauty. It's joy forever. Yep.

Murph You'll get you every time. Look at that solder trying to get a bit medieval on its arse. I think me slightly medieval. try new I'm unsold or it didn't work.

So yeah, it was really jammed in there. have to sort of crack her open so oops, still work. Do like that. Anyway, we're seen inside are organized oscillators.

Before we're going to find some insulation. it's just a regular crystal oscillator that they just a particular cut a more stable were cut but they keep at a temperature and then they insulate it so whoops oh oh hang on, that's coming out but the adjustment pot is not coming out. oops oops there's our crystal. so this is our heating element.

You can see the coil wrapped around there as our there's our for Mr. to regulate the temperature. Just got a single down in there with a helping hand from this end Stuber's and them as a meal. this one.

try and get some pliers and pull the the foam insulation out of there. Uh-huh There we go. I think there's our culprit, some solder down in there stopping it from coming out I think we'll break that out. it's still caught on some stuff this is.

this is real tricky business. Give her a bit of a poke right up the clock up. I Think we've got it. Ah oh jeez, it's not it.

Here we go. Ah, we're in. we're in like Flynn See the burn marks down the bottom? That's fairly typical. Now for those who will no doubt mention it.

I Don't think that this is asbestos insulation here that they've got in this thing. I Could be wrong, but I don't think it is. so you know any experts out there? Please correct me. But I will art treat it with care? Don't worry about that.

now. this is interesting because you can see the extensive burn marks on the back of this board. and that's caused by this power resistor. Well, one for who you will and fanboys.

Fantastic! There's a big power resistor here now. like like that obviously gets really hot and is that the heating element? but like I Don't think so because obviously like we've got no wrapping around the outside here with our thermistor. they're actually measuring the temperature. so I'm not sure.

Is that like an additional heater or something like that? Anyway, it is obviously designed to get hot and there's your board. For those that want to sit, there's your ten megahertz crystal. It's usually nothing fancy. you know it's it's a nice particular cut or whatever.

But anyway, the whole idea is that you know you get a decent cut crystal and you keep it at a very narrow temperature. You know it defined a temperature range regardless of what the ambient temperature is doing in. Bingo. Well, hence the name Oven eyes the crystal oscillator because it just sticks it in the oven and keeps it at a fixed temperature.

That's why it might take some time to warm these things up, but once they're at temperature, they're pretty darn stable. So desalted our capacity tour now. Variable trimmer cap from this other trimmer cap here. I'll measure that one too.

So we get a non nominal 15 puffs so it's not open. Hey, she's working. so it ain't the trimmer cap Trimmer cap. See, You can see the slug coming out.

now. There you go. That's that's fine. that's gone to the full extension now.

Seven puffs. That's exactly what you'd expect. Seven puffs up to like 20 or something like that. There you go.

End of travel: 20 Exactly. I Called it Brilliant. So there's nothing wrong with a trimmer cap. It's not that something else.

Well, it's not the other orange cap down there that measures a hundred in being on and that will one resistor 925 Ohms that ain't open I'm not sure what value it's supposed to be. can't see it. Was able to read the value on the side and it just says 1.02 5k. So Nine Hundred and twenty? Ohms.

Well, it's already in circuit I'd have to wordy solder and yep. D Soldered 1.02 Five marked near enough. Yeah, that's a seven for double Oh Classic D Code on that nineteen eighty. What? This is a like an old retrofit I assume it's 8000.

No, it'd have to be. They don't do zero zero week, do they? They do Zero One. So that's not it. All right.

I Think we might have our culprit one saddest-looking burned our tantalum there which was close to the resistor. In fact it's is physically tied onto there and bloody. LCR meter turned off. Trust me, it's You won't have to.

Trust me. Look at the value. Come on. slow as a wet week.

Look at that. It's a short. don't pull. it'll tear them.

Geez, why would you design it connected to the power resistor? Crazy. That's one poor little bastard. Two point I can still read it though. 2.2 mic, 25 volts.

So wat wat wat wat? please excuse a crew D of the model didn't have time to build it to scale a lot of pain. It will just whack some film caps in there can I can I put another Ted in there. So yeah, whack a film cap in. Just a parent up again and just like to see if that was the problem.

and that's if it's not, then that's probably as far as all I could be bothered to take it I Think right? For the purposes of today's experiment, we just leave it flapping around in the breeze. So let's switch her on and see. Yep, we're still got 10. That's a good start.

Still oscillates and it's higher than before. Isn't a couple hundred Hertz higher? All right, let's trim this. Gotta be careful not to touch anything because it was high voltage. We're trimming.

we know when up. Yeah, it's going down. it's going down. but I don't think it's going to go all the way with LBJ So, but it is certainly certainly trimming.

You know what is that? A 10 Hertz adjustment range or something like that? Yeah, it's coming down I think I need to I Think it needs time to time to warm up in its original configuration before it yet? Yeah, it's dropping. So I think we have a winner winner chicken dinner. but yeah, I'd like I'd have to physically reassemble it. That capacitor arrangement for the films are too physically big I'd have to do it.

But I think we've proven that it actually has fixed this thing and so that's what it was. I mean the cap was connected right up to. there was a power resistor like that. physically connected.

so the heats conducting through the leads as well as being radiated so like they were boom. You can see the burn marks on it and stuff like that. So there you go. It was a tantalum.

So for this video, I'm just going to finish this one out quick at the moment. don't have time. do I go find a suitable physical form factor cap for in there and uh and replace the thing. And physically like, you wouldn't do this like, long term like, especially for like a a frequency counter of this age.

Like you wouldn't like an eight digit counter of this age, it probably wouldn't bother. So I just sort of did this as like a troubleshooting exercise video. If your were serious about this, I've got an external Ten Megahertz reference anyway. I wouldn't bother using the internal organized oscillator.

I've already got this one with a probably a much better organized oscillator in it anyway. if I wanted to stand alone without my external Ten Megahertz Rubidium reference, geez, you can see it really really dropping now so it's going to come down thermally. It's not very good. it's you know, the coils half out there.

Maybe I'll get the thermal camera. I'll tell you what that that yellow wrapping around the thing in that coil that I said was like on here. In fact, it looks like that's not work. The power resistor in there is not working there.

It is there. Like it looks like nothing's heating up. Even that spot there is like is nothing. that's just like where I touched it.

So really, um, nothing to see here. Move along. now. it's just not heating up at all.

So yeah, I wouldn't even bother. like fixing this old crappy. yeah? I'm sure it was good for the day, but you know this what you know. forty five-year-old urbanised oscillator wouldn't bother like you would get.

You know if you really wanted to restore this and put an oven eyes dose later in it, then you would simply just buy one of the new one you know, or refurbished our 10 megahertz oscillators like a rubberised oscillators like I did for this one. Coming back down, there you go. We could eventually trim that one right in. But yeah, I you know you would get one of those urbanized oscillators and there's plenty of room inside this to retrofit it if you're really wanted to.

So anyway, yeah, I'm not going to I'm not going to bother a repairing that I just wanted to troubleshoot. So I hope you found that interesting. We can call it a repair even though we didn't finish the job off, but a troubleshooting and repair. If you liked that video as always, give it a thumbs up.

comment down below. Catch you next time.