EEVblog #363 - Gold Phone Teardown

hi welcome to the EEV blog hang on gotta get it hello Dave Jones no I'm not interested in upgrading my Altium license and no I don't want a subscription no I care that it's got new cloud functionality ah volt No not interested No PCB schematic ah no not interested bye and welcome to tear down Tuesday got something a little bit on the unusual side for you a classic payphone and Australian payphone a Telstra gold phone anyone probably over the age of 30 will have fond memories of making many a phone call on these Telstra gold phones they were everywhere in Australia they were the standard payphone 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 C T for Telstra phone but it's more affectionately known as the gold phone because of the color of this thing and you found these in our businesses and clubs and pubs and all sorts of things it was the classic payphone put your money in get your refund dial this is before the days of mobile phones kiddies yes you had to actually line up and use a line phone like this and somebody's already had a hack at this one because here's the here's the tray for the money inside of it and 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 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 vandal proof you know super rugged it weighs like 20 kilos or something it's a super rugged end designed to survive vandalism so it could be a bit of a pain to tear down may require a bit of percussive maintenance but we'll give it a go and go it could be interesting to see what's in side of these things now the interesting thing about one of these pay phones is that they're not powered from the mains at all they're actually are designed to work directly from the phone line so obviously inside of this thing is they're going to have a a storage storage capacitor or some sort of battery storage or something to allow it to build up to extract the power from the phone line typically I think it's about 48 volts not much current at all these it'll be designed for one standard 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 vertically the inside or down to the refund chute that requires solenoids that are relatively high power so we'll give it a go and try and crack open this thing and see what it has to offer so you know what we say here on the eevblog don't turn it on take it apart whoo-hoo now what it's got on the side here is two locks down here two key locks which I don't have the key for somebody's clearly had a go at that one there's a mode key switch here now this lock here is to open the cash drawer at the front there and I can see a couple of screws up under there so maybe all that mechanism might come out but this one over here is supposed to unlock chazzy somehow which I I think allows us to lift this entire top part off of the phone because you know it can't crack into there that's all welded shut and 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 detect that the cash drawer is inserted or removed from this thing so presumably they would know if you know the cash drawer the software will keep track if the how many times the cash drawer has been been removed and stuff like that so here's the sticker on the bottom there it is Telstra gold phones CT for 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 kinda piece of cake there you go tada we're in and here it is in all its glory and there seems to be a fair bit of electronics down on the main board down there which we'll check out caution static sensitive devices and if we have a look here we can see made in Japan so it's not by and ritsu presumably um the main PCB there is down in there is assembled by and ritsu in Japan but the whole thing the you know the whole phone itself is actually manufactured by your STC here in Australia but there you go it's a rather complex beast check out the check out the huge solenoid there look at all the all the various like a thousands and thousands of turns that's going to be a really high sensitivity solenoid there because it it because as I said this thing has to build up a charge so that it can operate the coin mechanism and because this is part of the coin chute 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 solenoid has to be because okay it operates in charges up operates once no problem but then it's got a recharge again in a very quick order to in order to operate the solenoid again so really it dumb it does require that high sensitivity solenoid that's why it is so here 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 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 ah check this out watch this and it folds forward on these pivot arms here and so you can service the ball down in there you can reach the various jumpers really beautiful design for service for ease of maintenance servicing and configuration because these are highly customizable they've got lots of dip switches and jumpers for various settings for various arts scenarios so 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 key switch down in here key switch has a little lever arm on it which I bent so I just bypassed that so I didn't have to rotate the switch at all I just 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 because it's got like you know twenty thousand combinations on the safe lock and less on the key switches but ergo once again manufactured in Australia by STC and Ritsu and it looks like an retsu manufacture the board as we saw now what I think I might actually do is just power this sucker up and see if I can get it working because then you know I might be able to operate the coin mechanism or something like that so I have no idea how to wire 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 chassis down in there so that looks like it's for the Lightning arrestor or something like that the earthing because these things aren't need external lightning arresters on them as part of the installation on these things so I'm guessing that the white and the blue is the phone line input and I'm not going to use a phone line I'll just use like a 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 I won't bother I might just up power that up with a 40 volt supply and see what happens and it looks like this little lever here is the on hook mechanism and I can hear a little micro switch going there because if you look at the case the case here's the here's the top of it so this that's the levers on top where you put the hand piece on there and it just pushes on this lever and that lever lines up with that one there now I've got to set to what 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 the moment I've got to set to current limit and we do have something on the LCD now it was drawing much more significant current before so I'm assuming that regardless of whether is on or off hook by the way it would now currently it's not really changing too much when I go on a rough hook but it was actually significantly ah drawing you know it was drawing like four or five watts or something like that so I can and then it just suddenly art dropped to zero so I can only presume that it was charging the caps internally because this is the first time it's been powered up for a long long time and needs to charge needs time to charge those caps up but it seems it seems to be working there's no I did see a lead come on inside briefly but I'm not sure what it's doing but let's get some much shrapnel here and put it in its a Australian look it's got the Platypus there is isn't it cute we will platypus I are 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 senses in there that are potted up there's that two of them either side we'll see that when we take this thing apart this actually just hinges like that and so does this keep at it almost floats there I'm not sure if that's actually a design feature or not but there's the there's the validator 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 Jex 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 sure I know we missed it it went through to the reject part there but it basically goes down behind the plastic and down a roller which puts it into the the coin box otherwise this lever here just shoots the coin out side of the mechanism and diverts it down another you know ramp down there which takes it through to coin reject mechanism but it doesn't seem to be except in coins at all let me probably because it's off hook let me switch it on hook okay it's on hook not reject again and maybe that forty volts was a problem cuz I've just put it up to 48 volts 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 we're onto something here perhaps let me try the coin again let me try and put it on and off hook what on hook okay we're on hook I don't see any increase in current Jordan changing current draw so let me okay it's on well no because you have to put the money in God can't remember how do these it you lift the handset then you put the money in isn't it so it should know it's rejected note reject again so I don't know no fail and I've totally disconnected the power there and you can see it still works because it's got storage in there which we'll take a look at to big super caps by the looks of it and I don't know I could read the manual on this thing a 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 for any more let's 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 apparently it's um something to do with when you've got multiple phones in parallel it the Bell in this scene doesn't tinkle there you go go figure and there's a test position okay there's various test positions test position maybe I should read that and have a look but anyway there's are various modes and all sorts of things for this thing to not only install it but 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 shoves all sorts of things down here and get it caught so they've thought of that they've got these little handles here on the side and bingo and just lift it out all you do is disconnect the ribbon cable at the back there and tada there is the entire coin mechanism and it looks like the coin mechanism is manufactured by anritsu again July 1989 there you go and here we go let's whack in a coin here I've got some shrapnel and let's whack it in and it's sure to come out you see it go down the ramp here that is the reject slot mechanism here because that little letter 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 now has dropped down into this bit down here 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 chute down in there you can see the coins down in there and there's another solenoid in here that once the call is finished if it can actually return the coins back through here or it can drop them into the coin box and that mechanism is operated what up they're falling 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 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 pre-loaded in there and let's give this a little nudge here and there we go at one two three four up five coins have dropped out into the coin box and if I put a reject coin in there because I haven't overridden the mechanism in there you'll see it flow down through the coin validator here which determines if it's a legitimate coin or not it's got some mark coil sensors in there I guess it can determine the 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 chute down in here it will go through this plastic chute 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 up if it goes there it goes boying 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 in your place 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 are lines up with this handset cradle thing on top if we push that it should release all of our coins into the release chute here instead of into the coin box because we want our damn money back so here we go there we go there we go it all came out into the read into the return chute here brilliant I love these things so let's pop the cover off here and take a look at the board tada ah it's relatively complicated and this is in - Mike - coin validator and here's the main PCB we've clearly got our main processor here what is it a Hitoshi hd60 305 in one of those high-density pin spacing dip packages and just a whole bunch of basic dip support circuitry up here there's a TLO 6-2 op-amp TLO 6-4 op-amp here and a few miscellaneous and long switches for o66 a couple of those around here not sure that is there it's a Hitoshi ha1 double 603 and a whole bunch of well as a couple of trimmer caps and a whole bunch of trim pots up here which have been dumped to set them so clearly they've obviously tweaked the levels on there for the forward detection of the particular coins because these coins are no Australian coins they'll have X amount of nickel in them and all sorts of other you know a ratio of metals in there and by putting presumably high frequency through these two coils down in here you can or modulating them in some way you can actually detect whether or not there is a valid coin in there and of course these things never be 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 there gunked-up it looks like they're just in a two wound coils probably on some sort of I don't know some sort of bobbin or something like that and as the coin 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 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 coin validator for it 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 you know you would get people trying to put you know and dodgy coins in these things so they had to be fairly advanced to actually detect that it was a real proper coin in there that doesn't seem to be because it's accepts different sized coins and stuff like that so they have to be tweet for each one that doesn't seem to be any size mechanism matching in there like there's no reference coin 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 it doesn't seem to be the case here there's just two coils up on the up on the validator mechanism there and as the coin passes by those two coils it's able to detect what type of a coin it is and well what size as well what a value because our coins are different sizes as well as well as different thicknesses and weights you can see we've got an e squared prom down here which is programmed presumably programmed with the data it needs to validate the coins so they're really fascinating things these coin validators I mean these coils are probably operating at many you know tens of kilohertz maybe even 100 kilohertz or more or something like that and through there's there's two of them as it travels through it as you know obviously one's not good enough so they're using a second one to do some extra validation there and you know it's I'm sure you could 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 aspect to it but you can bet your bottom dollar that there's some stuff tweaked in the e squared prom and also so these pots down here which have had the set glue put on them they do it as well now I could pair up this thing of course and try it 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 tight in a thousands of windings on that sucker so they're really sensitive so they're able to pull in that actuator arm with that 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 milli watts 12 milli watts something like that six is seven milliamps to to actuate that Queen 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 that 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're going to follow on button which is just a soft carbon back button there we've got our keypad nothing happening there very old-school to the solder joints in the board and it looks it like it's done by someone else Natsuko nit suka or something like that so that's its own mechanism we're got our ringer here and 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 network processor line board in the back so that's the most interesting thing left in this thing because all this stuff out the front I'm not even going to bother to take it out and there's a dip switch we saw right at the start there so let's lift out this board see what we've got and once again it's all designed for ease of servicing just take these cable harnesses out here disconnect the cable coming in and they've got these little plastic retainer Clips and that forward 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 they're classic double sided stuff you know really classic lay out nice silkscreen all individually you know laid out in sections like that so that you can so when you're repairing these things 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 section so that you know if one particular section fails bang you can go straight into the section identify it or repair it it looks like we've got a bunch of test points all the way along here because there is no cable harness which goes into that brilliant labeled and numbered fantastic there's a little daughter board 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 determine how much a call cost basically that's why it's a socketed because people in the field need to change this as the bastards increase the cost of that phone call they go around they plug in a new module and bingo you charge 40 cents for a call instead of 30 cents last week bastards and look at our processor here it's an NEC 7805 pretty old-school stuff lots of diodes and resistors lots of resistor networks down here what else oh we got arm some single inline resistor networks curiously and ritsu make their own IVA they make their own resistor networks like that or they've had them and redtube branded and bingo here's the line capacitors they're a nought point 1 farad there's two of them NEC presumably there's two of them for redundancy I would guess that aligned capacitors which are charged up which allow this thing to operate to allow it to dump power to those solenoids and power the thing because if it was just from the line then it wouldn't be able to do that it's got to have some reservoir storage on the board there's an a QC whatever that is as t CB DC 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 Rhian detection I'd you know there'd be all sorts of stuff and I should probably read the manual but this and stuff for the LCD as a couple of relays there as input protection stuff we've got some mobs there by the looks of it are they lay low certainly look like it input protection resistors there and there you go a couple of Dipple inks to set various stuff and indicator LED 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 ever come to Australia and you have an emergency don't dial nine-one-one no not 911 dial triple zero don't know what happens if you don't know I'm living in Australia nothing you might get an Indian call center or something who knows pet you certainly won't get the emergency services triple zero and you can see at the time the call cost was minimum fee 30 since this was designed in was was manufactured in 1989 as you can see accepted 10 cent 20 cent 50 cent and one dollar coins but I can remember back when phones didn't accept one dollar coins because well we didn't have them we had $1 notes we only switched over in about 1984 or there abouts to the dollar coin from the dollar note they would have had to go around rush around and change all the coin validators I guess although back then you know dollar was worth lot heck you buy a lot of lollies for a dollar let me tell ya haha anyway that is inside a classic Telstra gold phone I hope you enjoy that bit of a trip down memory lane there for Australians anyway and quite fascinating to see what's inside these things especially with the coin validator mechanism and stuff like that so if you want to discuss it jump on over to the EEV blog for it and if you like tear down Tuesday please give it a big thumbs up catch you next time

Channel: EEVblog

Views: 139,469

Rating: 4.8684578 out of 5

Keywords: telstra, gold phone, ct4, payhone, teardown, pcb, hack, electronic, coin validator, mechanism, australia

Id: we5zxv5c00g

Length: 33min 18sec (1998 seconds)

Published: Tue Oct 02 2012