Hi Welcome to the Eev blog! Hang on. Got to get it. Hello Dave Jones No I'm not interested in upgrading my Alium license No I don't want a subscription? no I Ah I Don't care that it's got new Cloud functionality not Vault No not interested? No PCB schematic Ah no, not interested. Bye and welcome to tear down Tuesday Got something a little bit.

Uh, on the unusual side for you, a classic pay phone and a Australian pay phone? A Telstra Gold phone? anyone? uh, probably over the age of 30 will have fun memories of making many a phone call on these Telra gold phones. They were everywhere in Australia They were the standard pay phone that you found absolutely everywhere and we're going to tear it down and see what's inside of this thing now. its technical name is the Ct4 uh Telra phone, but it's more affectionately known as the gold phone because of the color of this thing. and you found these in uh, businesses and clubs and pubs and all sorts of things.

It was the classic pay phone. Put your money in, get your refund dial. This is before the days of mobile phones kitties. Yes, you had to actually line up and use a line phone like this.

and um, somebody's already had a uh hack at this one. Um, because here's the uh, here's the tray for the money inside of it. and uh, these are naturally quite difficult to open I don't have the key for the things. somebody's had a had a go at these, so uh, this actually could be quite difficult to hack apart.

These are welded around here. It's all steel, it's designed. These are designed to be vandalproof. You know, super rugged.

It weighs like 20 kilos or something. It's uh, super rugged and designed survive vandalism so could be a bit of a pain to tear down. may require a bit of percussive. Maintenance But we'll give it a go a go.

It could be interesting to see what's inside of these things. Now, the interesting thing about Uh, one of these Payones is that they're not powered from the mains at all. They're actually uh, designed to work directly from the phone line. So um, obviously inside of this thing is they're going to have a uh, a storage, uh, storage capacitor or some sort of uh, uh, battery storage or something to allow it to build up.

uh to extract the power from the phone line. typically I think it's about 48 volts, not much current at all. these. um, it'll be designed for one standard uh phone load, so it's designed to charge up inside so then it can operate the solenoids and things to give you your refund and you know for the coin mechanism and to divert it either inside or down to the refund.

Shoot, that requires um, solenoids. Um, that are relatively high power. so we'll give it a go. um and try and crack open this thing and see what it has to offer.

So you know what we say here on the Eev blog. don't turn it on, Take it apart. Woohoo! Now now what it's got on the side here is uh two locks down here. two key locks which I don't have the uh key for somebody's clearly had a go at that one.

there's a mode uh key switch here. Now this lock here is to open the uh cache drawer at the front there and I can see a couple of screws up under there so maybe um, all that mechanism might come out. but this one over here is supposed to unlock the shazzy somehow which I I think allows us to lift this entire top part off of the foam because you know you can't crack into there. that's all welded shut and uh well I think we've got to somehow Jimmy This thing open.

One of the first things I noticed was a little micro switch down in the cash drawer here and that's clearly to detect that the Castel is uh, inserted or removed from this thing. So presumably um, they would know if uh, you know the cash draw. The software would keep track if the C how many times the cash draws been uh, been removed and stuff like that. So here's the sticker on the bottom there it is Telstra Gold Phone Ct4 Telecom Australia Serial 35 contract blah blah blah manufactured 1989, made in Australia not Austria Lockpick My Ass Dremel time and Pop Goes the Weasel There we go should now just lift off kind of piece of cake.

There you go, Taada, we're in and here it is in all its glory. and uh, there seems to be a fair bit of electronics down on the main board down there which will check out Caution: static sensitive devices and if we have a look here, we can see made in Japan so it's not uh by an ritsu presumably um, the main PCB there is down in there is assembled uh by and ritsu in Japan But the whole thing, the you know, the whole uh phone itself is actually manufactured by STC here in Australia but there you go. It's a rather complex Beast Check out the uh, check out the huge solenoid there, look at all the uh, all the very. It's like a thousands and thousands of turns.

that's going to be a really high sensitivity uh solenoid there because it, uh, it. um, because as I said, this thing has to build up charge so that it can operate. uh, the coin mechanism. and because this is part of the coin, shoot the coins.

The coins go in here and this is part of the coin acceptor reject mechanism or something like that and that's a very high sensitivity. uh solenoid, It has to be because, um, okay, it operate, it charges up, operates once, no problem, but then it's got to recharge again. uh in a very quick order to um in order to operate the solenoid again. So uh, really? it? um, it does require that high sensitivity solenoid.

that's why it is so huge by the looks of it. Static sensitive devices. We've got IDC headers all over the place. This is part of the coin acceptance mechanism.

All of this Jazz around here, presumably. um, we've got a lift and internal lift handle. which oh yeah, okay, that lifts the entire mechanism out by the looks of it. So yeah, here we go.

I Can lift that? There we go. Tada I can lift that whole mechanism out. Look at this. Oh, check this out.

Watch this and it f folds forward on these pivot arms here and so you can service the board down in there you can reach the various jumpers. Really beautiful design for Ser for ease of Maintenance servicing and configuration cuz these are highly customizable. They got lots of uh, dip switches and jumpers for various Um settings for various uh scenarios. So um yeah, you really have to get inside these things to customize them and they've done a beautiful little job there.

Look at that. Ah, wonderful. I Could play with that all day. and in case you're wondering how it actually clamped the thing shut, you can see these two arms here go inside the plastic case and they move forward and back based on the uh key switch down in here.

key switch has little lever arm on it which I uh bent so I just bypassed that so I didn't have to rotate the switch at all I just uh once I got in, got in with the screwdriver, straight in, bent the arm and bang we were straight in like that easy peasy lemon squeezy. and of course once you open it up there you go. you find the safe lock number and the key switch number written in there cuz uh, it's got like you know, 20,000 combinations on the Uh safe lock and uh Less on the Uh key switches. But there you go.

Once again, manufactured in Australia by STC and Ritsu and it looks like an Ritsu manufactured the board as we saw now what I think I might actually do is just power this sucker up and uh, see if I can get it working cuz then um, you know I might be able to operate the Uh coin mechanism or something like that. so I have no idea um how to this up. At first glance we've got blue, white and black but if you look at the black, there's it goes into here and the black actually has a wire which goes down onto the shazzy down in there so that looks like it's for the Uh lightning arrester or something like that. the Earth in cuz these things um, need external lightning arresters on them as part of the Um installation on these things.

So I'm guessing that the Uh White and the blue is the Uh phone line input and I'm not going to use a phone line I'll just use like a uh a well I don't have a 48 volt I think the maximum power supply I got here in the lab is about 40 volts. I could put them in series, but uh I won't bother I might just power that up with a 40 volt uh Supply and see what happens. and it looks like this little lever here is the on hook mechanism I Can hear a little micro switch going there because if you look at the Uh case the case. here's the Uh.

here's the top of it. So there that's the levers on top where you put the Uh hand piece on there and it just pushes on this lever and that lever lines up with that one there now. I've got it set to 40 volts here which is the maximum that Supply can go to. my other one goes to 42.

I can take it up to 48 but uh, the moment I've got it set to current limit and we do have something on the LCD Now it was, uh, drawing much more significant current before. um so I'm assuming that uh, regardless of whether it was on or off hook, by the way, it would uh now currently it's not really changing too much when I go on or off hook, but it was actually significantly uh drawing. You know it was drawing like four or five Watts or something like that. So I can.

and then it just suddenly, uh, dropped uh to zero. so I can only presume that it was charging the Caps internally cuz this is the first time it's been powered up for a long, long time and uh, needs to charge. needs time to charge those caps up, but it seems, um, it seems to be working. There's no I did see a lead come on inside.

uh, briefly. but I'm not sure what it's doing. but let's get some uh, shrapnel here and uh, put it in. this is Australian look, it's got the Platypus There he is, isn't he? Cute little platterpus on our 20 cent coin.

Now if we have a look at the top part of the coin validator mechanism, you put your coin in here and it drops down and flows through. These wires here come from Those sensors in there that are potted up. There's uh, two of them either side. We'll see that when we, uh, take this thing apart, this actually just hinges like that and so does this keypad.

It almost floats there. I'm not sure if that's actually a design feature or not, but there's the uh. there's the validated there and then that kicks in a solenoid behind here like this. so it pulls it in bang like that and that determines whether or not it ejects the coin.

So let's drop in the coin here and we'll stop it there. and once it passes through that if it detects that it's a valid coin, then it pulls in this catch here and it should. Oh no, we missed it. It went through to the reject part there.

but uh, it basically goes down behind the plastic and down a roller which puts it into the, um, the coin box. Otherwise, this lever here just shoots the coin outside of the mechanism and diverts it down another, uh, you know, uh, ramp down there which takes it through to the coin reject mechanism. but it doesn't seem to be, uh, accepting coins at all. Let me, uh, probably cuz it's off hook.

Let me switch it on hook. Okay, it's on hook. no reject again. and maybe that 40 volts was a problem cuz I've just put it up to 48 Vols and listen to this ping.

Here we go. I'll connect it. There we go. It's making some lovely noises there, so clearly, um, where on to something here? perhaps? Let me try the coin again.

Let me try and put it on and off hook. Well on hook. Okay, we're on hook. I Don't see any increase in current draw or changing current draw.

so let me. okay, it's on. Well, no cuz you have to put the money in God can't remember how to these. You lift the handset, then you put the money in.

isn't it? so it should? No, it's rejected. No reject again. So I don't know. No fail.

and I've totally disconnected the power there and you can see it. Uh, still works because it's got um, storage in there which we'll take a look at. Two big super caps by the looks of it. um and H I don't know I could read the manual on this thing and figure out how to set it all up and make it work.

Maybe it doesn't even work at all? I don't know. I'm not going to dick around with it anymore. Let's uh, take it apart and see what we can see and check this out on the underside of the lid here. Wiring diagram: remove strap and fit anti tinkle module anti- tinkle module I had to Google that and uh, apparently it's um, something to do with.

uh, when you've got multiple phones in parallel it the bell in this thing doesn't tinkle. There you go. Go figure. and uh, there's a test position.

Okay, there's various test positions. Test position: Maybe I should, uh, uh, read that and have a look. But anyway, there's uh, various Uh modes and all sorts of things for this thing to, uh, not only install it, but uh, set it up as well. Now one of the servicing requirements for these phones is that you have to be able to get out jammed coins because kids and just general idiots shove all sorts Of things things down here and get it caught.

So they've thought of that. They got these little handles here on the side and Bingo can just lift it out. All you do is disconnect the ribbon cable at the back there. and TDA There is the entire coin mechanism and it looks like the coin mechanism is manufactured by En Ritsu again.

July 1989 There you go and here we go. Let's whack in a coin here. I Got some shrapnel and let's whack it in and it should come out. You see it go down the ramp here.

That is the reject slot mechanism here because that little Le that little solenoid in there hadn't activated that lever down in there. Okay, I'll keep that closed and you see how it popped out the reject mechanism here before. if we put our coin in it, it now has dropped down into this bit down here with which holds the coin in or holds the coins in place. So if you're familiar with that just in case you want change.

so you put all your coins in Tada Like that and they're all held in this shoot down in there. You can see the coins down in there and there's another solenoid in here that once the Um core is finished if it, it can actually uh, return the coins back through here or it can drop them into the coin box and that mechanism is operated. Who? Oh, they're fallen out by this massive High sensitivity coil here and if I operate that with my finger, Here we go, we should find Tada There we go. Each time it operates, it drops out a coin and you'll notice it's dropping out here here which is dropping into the coin box, not into the reject.

No, that's it. I Got all my coins out there. we go and we can see that up close here. I've got my five coins preloaded in there and let's give this a little nudge here and there we go.

1, 2, 3, 4. Oh, five coins have dropped out into the coin box and if I put a reject coin in there cuz I haven't overridden the mechanism in there, you'll see it flow down through the coin validator here. Uh, which determines if it's a legitimate uh, coin or not. It's got some coil sensors in there I Guess it can determine the uh, you know, the type of metal and things like that.

There's various techniques for that, but it'll instead of going down into this metal, shoot down in here. it'll go through this plastic. Shute It'll jump out of this rail, into the plastic Chute and down. So we should be able to see it come out here and down there.

Here we go. Oh, if it goes there, it goes boing. Okay, now let's say you've put all of your coins in here and you've attempted to make your phone call and it doesn't do anything and you replace the handset back on the Cradle it needs to return your coins. So to do that it when we hit this mechanism here, all of the which uh lines up with this handset cradle thing on top.

If we push that, it should release all of our coins into the release. shoot here instead of into the coin box cuz we want our damn money back. So here we go there, We go there we go. It all came out into the Re in into the return shoot here.

Brilliant! I Love these things. So let's pop the cover off here and take a look at the board. Taada Oh, it's relatively complicated and this is in Anritsu Mark 2 coin validator. And here's the main: PCB We've clearly got our main Uh processor here.

what is it? a Hitachi HD 6305 in one of those um, high density, uh pin space in dip packages and just a whole bunch of uh, basic, um, dip, uh, support circuitry up here. There's a T62, opamp, T64 Op amp here, and uh, a few misscellaneous analog switches 4066, couple of those around here. not sure what that is there, that's a Hatachi ha63 and uh, a whole bunch of, uh, well. there's a couple of trimmer caps and a whole bunch of trim pots up here, which have been gunked to set them.

so, um, clearly they've obviously tweaked the levels on there for the Uh for detection of the particular coins. Because these coins, you know Australian coins. they'll have um x amount of uh Nickel in them and all sorts of other um, you know, a ratio of metals in there. and by putting uh, presumably high frequency through these two coils down in here, you can or modulating them in some way, you can actually detect Um whether or not there is a valid coin in there.

And of course, these things have never been able to tell the difference between an Australian and a New Zealand coin. So you can see the validator coils there. There's two of them they gunked up. It looks like they're just, you know, two wound coils, probably on some sort of um I don't know, some sort of bobbin or something like that.

And as the coin uh passes them, it's able to detect what type it is and if it's valid. I mean this is a fairly primitive one. there's much more uh Advanced ones if you really want to get into it. And then you get into note validation which is a a really Art and Science in itself.

But I'm willing to bet that that's a fairly Advanced uh coin validator for its time because well, you had to cut down on fraudulent uh, you know, use back when you know the old platypus was actually worth something. Um, you know you would get people trying to put you know, dodgy coins in these things so they had to be fairly Advanced to actually detect that it was a real proper coin in there. There doesn't uh, seem to be because it accepts different um, size coins and stuff like that so it' have to be tweaked for each one. There doesn't seem to be any Uh size mechanism uh, matching in there like there's no reference coin.

Um, some of these coin validators will actually have a reference coin in there so that it can determine you know the size, the thickness, and the material, and all sorts of stuff. So it's got something to work from. But uh, that doesn't seem to be the case here. There's just uh, two coils up on the uh up on the validator mechanism there.

and um, as the coin passes by those two coils, it's able to detect what type of Uh coin it is and um, well, what uh, size as well. What a value! Because our coins are different sizes as well as well as different thicknesses and weights. And you can see we've got an E Prom down here which is programmed uh, presumably programmed with the Uh data it needs to validate the coin. so they're really fascinating things.

These coin validators I mean these coils are probably operating at many, you know, tens of kohtz, maybe even 100 kohtz or more or something like that. And uh, through, there's there's two of them as it travels through it. Uh, as you know, obviously one's not good enough so they're using a second one uh to do some extra validation there and you know it's I'm sure you could, uh, read up all day on how these electronic coin validators actually determine that these are real coins you're putting in in here and not just some, you know, dummy or some foreign currency which has a slightly different um aspect to it. but you can bet your bottom dollar that, uh, some stuff tweaked in the E prom and also these pots down here which have had the uh Set uh, glue put on them.

They do it as well now. I Could power up this thing of course and try and you know and measure, look at the waveforms and see how the frequency I Assume that the frequency is going to slightly change with the type of metal and you know all sorts of stuff like that and might do that in another video. but that's not for today. And as I mentioned, the solenoids in these things very high sensitivity.

T You know, thousands of windings uh, on that sucker. so they're really sensitive so they're able to pull in that actuator arm with, uh, not much current at all. So just how much current does it take? Well, I Got my power supply set to a minimum 10 milliamps constant current at 12 volts. There we go, and there it is.

It's only you know. 10 M 12 M something like that. Six 7 milliamps to Uh to actuate that coin release mechanism. Brilliant.

But that's not for today. Let's take a look at, but that's not for today. So let's take a look at the rest of this phone and see what we got. And really, there's not much else on the front here.

We've got our LCD going through this ribbon cable here. there's no circuitry on the back of that. We got our followon button which is just a uh, a soft carbon back button. there.

we've got our keypad. Nothing happening there. very old school look at the solder joints and the board and it looks like it's a done by someone else Nito Nitsa or something like that so that's its own uh mechanism. We got our ringer here and uh, we've got a little patch board down here which just you know, joins things in to the wiring harness which goes back to the main uh network uh processor line board in the back so that's the most interesting thing left in this thing cuz all this stuff out the front.

I'm not even going to bother to take it out and there's that dip switch we saw right at the start there. So let's lift out this board, see what we got, and once again, it's all designed for EAS of service and you just take these uh, cable harnesses out here, disconnect, connect the cable coming in and they've got these little plastic retainer clips and that board Tada just slides out. There it is and let's take a look at this sucker. It is very old school Telecom like look at all the square traces on the PCB There classic double-sided stuff, you know re really classic Layout: nice uh silk screen all individually? um uh, you know.

uh La out in sections like that so that you can. So when you're repairing these things, they are designed to be repairable. of course that's why they're all through hole but they're all modular so the service manual would have all the info on each particular um section so that you know if one particular section fails bang, you can go straight into the section, identify it, and repair it and it looks like we've got a bunch of test points all the way along here cuz there is no cable harness which goes into that. Brilliant, labeled and numbered.

Fantastic! There's a little daughter bought up here not sure if that comes out. Yeah, there we go there. There we go. It's a dip.

There you go. it's a little dip board and that is the Tariff unit and this tariff unit would uh determine how much a CO costs. Basically that's why it's uh, socketed because uh, people in the field need to change this. As the bastards increase the cost of that phone call they around they plug in a new module and bingo, you charge 40 cents for a call instead of 30 cents.

Last week, bastards and we got our processor here. It's an NEC Uh, 7805. Uh, pretty old school stuff. Lots of dodes and resistors.

Uh, lots of resistor networks down here. What else we got? um, some uh, single in line resistant networks. Curiously, and Ritsu make their own. Either they make their own resistor networks like that or they've had them and Ritsu branded.

And bingo. Here's the line capacitors. They're a 0.1 farad. There's two of them.

NC presumably there's two of them for redundancy. I would guess they're the line capacitors which charge up which allow this thing to, uh, operate to allow it to dump power to those solenoids. and Power the thing because if it was just from the Uh line, then you wouldn't be able to do that. It's got to have some Reservoir storage on the board.

There's an Aqc, whatever that is. There's TC BDC some unpopulated stuff. DD If you're into your Telecom stuff, I'm sure you're screaming at me. You know exactly what all this stuff is doing.

You know, ring detection. You know there'd be all sorts of uh stuff. and I should probably read the manual, but there's some stuff for the LCD. There's a couple of reays there.

There's input protection stuff. We got some Ms there. By the looks of it are they. They look certainly look like it.

Input protection resistors there and uh, there you go. Couple of uh, dip, a couple of Jumper links to set various stuff and indicator Le and that's about all she wrote. but I Love the modular design of this thing. It's brilliant and just as a heads up for you, Yanks If you're going overseas, you ever come to Australia and you have an emergency.

don't dial 911. No, not 911. dial triple 0. Don't know what happens if you dial 911 in Australia nothing.

You might get an Indian call center or something. who knows. but you certainly won't get the Emergency Services triple zero. And you can see at the time the core cost was minimum fee 30 cents.

Um, this was designed in well. This was manufactured in 1989 as you can see accepted 10 cent, 20 C50 and $1 coins. But I can remember back when phones didn't accept $1 coins because well, we didn't have them. We had $1 nodes.

we only switched over in about 1984 or thereabouts to the dollar coin. From the dollar note, they would have had to go around rush around and uh, change all the coin validators I guess Although back then you you know dollar was worth a lot. Heck, you can buy a lot of lollies for a dollar. Let me tell you anyway, that is inside a classic Telstra gold phone.

I Hope you enjoyed that bit of a uh uh trip down memory lane there for Australians anyway and quite fascinating to see what's inside these things, especially with the uh, coin validator mechanism and stuff like that. So if you want to discuss it, jump on over to the Eev blog forum and if you like tear down Tuesday Please give it a big thumbs up. Catch you next time.