Hi welcome to Tear down Tuesday Yes, we got a rather mundane item for you today. It's a cash register I scor this one from the dumpster downstairs and well, I thought, you know, why not? I Don't think there's going to be a huge amount in here. There's a thermal printer, there's a keypad, there's going to be a processor inside, there's a display up the top here, and a vacuum florescent display on the bottom. and the cach uh thing which I don't have the key for and it does actually work.

it is fully working. It obviously came uh from a nearby cafe or something who, uh, got rid of it I thought we' crack it open and have a look, eh, you never know your luck. Now this one's a Kuan brand. If I'm pronouncing that correctly, it is German and it's the Qmp 3282 and obviously it has, uh, this customizable uh keypad here, which obviously you can actually get the overlays in here.

There we go. Looks like it's had a couple of overlays and you can just, uh, print these out yourself and uh, presumably program it yourself and uh, looks like they've had a a couple of goes at that. So uh, there you go. Maybe you can see, uh, prices change over time and stuff like that.

And really, there's the uh, there's the overlay on the bottom and that's pretty much fixed. Is that stuck down? Yeah, it looks like it doesn't feel like a quality tactile. Dome that's for sure. So I might actually try and tries that off.

and uh, have a look to see if they do have a proper metal dome in there. feels very spongy and no tactile, uh, feedback at all, but you'd think that that'd have to, um, be pretty good quality to, you know, last in an environment like this. And obviously you got the full uh rubber membrane on that because you're working in a cafe. There's spillage and all sorts of grime and grot all over the place and uh, there you go, but there it is made in Germany Awesome thermal printer.

Doesn't have any uh, paper in it, but uh. anyway, let's have a look and on the back here, it's definitely seen better days. anyway. it's got a PC input presumably like a Serial port and a scanner probably another like a Serial maybe custom interface I don't know, um and a vacuum fluorescent uh display on the back I won't bother powering it up cuz that violates the rule don't turn it on, take it apart but yeah, I have and it does work now because I didn't have the key for this thing I Thought I'd have to pick the lock to get the cash tray out, but as it turns out, then, just get your finger in here and lift that up and bingo out puffs the tray.

There you go I'm not sure if all cash registers have that, but this one certainly does and we're in like Flyn look at that. Um, obviously it's got a solenoid in there that actually releases a cat I Can push that back in, but then it locks in place. of course, get the uh software to actually release the mechanism. um on that thing and uh, this tray just pops out.

It's all crusty I haven't bothered to clean that and hey, looky what we have here to change price key to: PE to scroll through products Cash P you to finish there you go. somebody's written some notes and uh, how to take daily totals and uh, how to add to account blah blah blah blah blah but no, nothing else hidden in there. And there's the soleno in the back of this thing. there's a spring and uh, the catch under there.

You can get your finger off there, but there's a cable then going up through to the top there which the process can then activate when you go. open when you finish the transaction and open the cach to draw. I'm not sure exactly how to get this top part here here off it. sort of.

oh yeah, could be a couple of screws inside here or something like that holding it in. No hang on. As it turns out, there's a thumb screw underneath here like this and you whip that off and Tada look at that. we're in and that membrane keypad was stuck down on there and I just peeled that off in one piece and that's and I just uh, pulled these straight out I didn't have to get into the boards of course these aren't uh, they're just held in place by friction.

that's all. so you can just pull those out through the slot on the top here. and uh I know you might keep that for some sort of I don't know interactive project or something like that. It's nice that it's clear and see through, so I think you'd keep that more for the things that you can't think of.

those sort of hack projects that you have no idea about yet, but might come in handy one day. and what do you know? I found the key look at that doesn't look too secure and of course that bottom tray was Earth to that would be a local safety requirement to have that metal tray. Earth and I've just undone the screws there and today we're in. Awesome! o Interesting.

and there's our main processor board. It's interesting that they've got uh two, you know, they got a daugh board sitting on top of that, so we'll have a closer look at that in a minute. And they got a ribbon cable going over to a Serial board at the back here obviously that looks like an Altera Max uh plld on there actually and then power supply under here with a nice little uh, plastic cover on it I Rather like that. so that's the main switch mode Supply and we got some Ferites there cables wrapped through there, a couple of turns just to uh, take the edge off the Emi there and uh, that's a a key switch on the uh side.

Actually, that's probably what the that might be what the key is? uh to change the modes actually on this thing. Rather, it's got a mode switch on the side rather than the cach tray I'd have to actually try it. Yep, that's the key for the mode switch. There you go.

Not for the uh cash drawer. that's why I found it inside the printer. uh, compartment in there. They kept it in there I Don't know.

this is like to set it up or something like that, put into different test modes or you know, programming modes or whatever. You'd have to read the manual Now of course, when you do tear Downs like this, you're always looking at what sort of Parts you can salvage and there's a very nice little vacuum fluorescent display module there, complete with all the driver stuff on the bottom. I Don't know if you'd be able to get any data on that, but you could, probably, uh, figure that out. I Mean it's only you know, there's not many wires on that interface there, so that's a really neat board.

And of course, the good thing about this uh interface here is that well, you've already got the working unit so you could get in there while it's operational and actually probe these pins. and uh, you know, work out what? um, data format. Obviously it's some sort of, you know, serial, uh type thing or 4-bit interface or something like that, so shouldn't be too hard to reverse engineer that at all. Wouldn't take that much time if you wanted to reuse that.

That's a nice looking module. Oh beautiful. And they've actually put this Ferite on as uh, before they've installed this thing. How do I know that? Well, they got a nice big cut out here in the case where that Ferite actually pops up through.

otherwise you wouldn't be able to get the damn thing up through there. and bingo more. Salvage Look inside the display. We got ourselves a power Te LCD module.

They're a No and brand. It's got the part number on there. no doubt you can get the Uh data for that. And yep, I Just checked.

You bet we've got the data sheet for that thing. Fantastic! It turns out this is a standard Uh Hitashi pinout LCD interface you're familiar with, but the extra pins pins 15 and 16 uh which are normally the uh, backlight pins. they're actually uh, chip select so two different pins and then a reset pin I think's pin 17 and then a couple of others which uh yeah, so perfectly usable. What a great score! Well hello, look what we have on the back here.

That's a bit how you're doing. They've bodged something in there I'm going to take A closer look. Aha, it's a 5 volt under Voltage Sens chip. It's a Motorola MC 34164 P-5 that's a 5vt version.

Also comes in a 3vt version. What's that? Basically a uh reset uh chip which you gives a reset output for this thing going to the reset pin when you get under voltage. So obviously some sort of hack here where they've had an issue with this product and you know, some sort of bug or something like that. They couldn't be bothered.

uh, fixing. You know the power supply is not ramping up fast enough for this thing to reset or something like that. They had issues with this particular LCD chipset in terms of reset and power on and they've added this reset Circ for under voltage lockout. So all they you know for power glitches or something like that the LCD might not reset properly and might switch off or get corrupted or something like that.

So they've bodged on this reset chip. Interesting. and there's that. Altera Max PL I was talking about uh EPM at 3064 there.

so you know, fairly old school PL Aha And there's our Rs232 driver there. Hn 2 W1 old school intercell stuff. There's an interesting way to clamp your wires down look at that that actually is strain relief and sort of clamp that actually works Pretty good I Like that, but it's clearly bodged in there because this is, uh, the um, one of the standoffs for the uh rear board here. So yeah, they've just, they just haven't used that and uh, it was molded in.

There's a matching one over here as well. So yeah, maybe a bit of an afterthought. Now, if we have a look at the main board here, this uh daugh board on top is actually directly solded in with that jeel in line pin header, so they haven't actually bothered to, uh, put a connector in that. That's that's.

rather disappointing, so you can't get that bastard out. Um, without desoldering the whole blinking lot. How annoying. Anyway, what we have here is an Altera Max um PL Again, and there's two more on the bottom board underneath this.

so they're really going to town there. And then we have an Atmail um, at 89 C52. So it's an 8051, you know, fairly modern 8051 uh processor. So that's what's run in this top board.

which is, of course, the thermal printer. uh board. That's the thermal printer interface there. So um, that is.

Uh, so they've decoupled the functionality of that from the main processor under here and they got two. Those two there are Max 2, PLS, or Max uh PL These are not even Max 2 Need to have a look at that puppy there. And we got ourselves an STL 6219 stepper driver uh stepper motor controller there. And up here is an L293 that's actually a quad uh, pushpull driver can Source Basically, uh 1.2 amp Peak on all four channels.

Not a bad little beast at all. That's basically exactly what you need for a thermal printer interace. you need the push pull driver up here for the Uh heater for the thermal heater. and then you need, uh, the steeper motor driver down here as well.

And presumably they've uh, decoupled all of the hard task of actually controlling the thermal printer into the Um into the Pl. Here, they're not doing it all in software up here, so you can see the Trac is actually running back down here to the max. 2 max PL It's not a Max 2 keep calling a Max 2, it's an Altera Max it's the original and that RDC R882 under there I Had no idea what that was, but it turns out there's an RDC uh, Semiconductor Company that's their name and this R882 is a 16bit risk DSP processor Who The hell's ever heard of that and it didn't make any sense for it to be like a its own architecture or whatever. And it turns out it's not.

It's software compatible with the Intel 80c 186. So there you go: 16bit 18 86 processor just from a, you know, a cheaper, more obscure, uh, company. Um, and they've probably risked it or some. You know, they've sort of like re-engineered it.

but it is software compatible, so you can presumably use all the software tools for the Ad 186 to actually develop your software for this thing. So there you go. Um, as I said, two other Max PLS under there wh there and there. so I don't know they're driving all of this and I they're doing off.

You know they're um, offloading lots of Uh tasks from the two uh processors in here. the main processor down the bottom, the top, one 8051 controller just controlling the thermal printer up there. So they they've really, um, offload of those tasks. All that glue, logic and stuff like that stuck it all together in those PS They're probably not massively complicated, but uh, worthwhile to uh, cuz ultimately, there's not much else in here, but you don't really need anything.

I mean you need a processor, you need some RAM and some ROM and uh, you need a driver board for the uh thermal printer. But apart from that um and and a Communications interface. but apart from that, you don't really need much else. so not entirely sure what they're doing in those two Max uh PLS on the bottom there and that makes sense.

a nickel metal, high dried backup battery there? um, 70 Mah hours little tiny little thing that charges up. This explo explains why when I booted this thing, it went through an entire boot process and uh, did all sorts of resets and calibrations and all sorts of uh uh stuff. And when I powered it up a second time, it just instantly and that took some time to boot up. When I powered it up a second time, it just booted up instantly.

So obviously it. uh, yeah, that was dead flat. Of course it'd expected to be and that there looks like a decent little quality. uh.

switch mode controller I Like that, it's uh, well laid out and looks like it uses Quality Parts That's really quite. uh, nice. Nice heat shrinking around. uh, the input.

uh, looks like a a small common mode choke there. and all the uh, the power resistors are all the dodes. everything all raised off, and uh, that is really quite nice. And Nipon Chemicon capacitors.

No worries whatsoever. Yeah, Nipon Chemicon again. no dramas whatsoever. so that's nicely engineered.

Look at that. That's pretty decent. Good on the Germans and this is interesting. Look at these two black wires here.

These go off, uh, to the thermal printer, but they're not a supply output. take a look. it's two ground pins. so they're actually getting return High Current return ground coming back from from the thermal printer instead of it all traveling through that digital board there.

So they got the power running over, but then a separate ground Loop running back just for the thermal printer. So you don't get all of those current pulses going through your ground plane on your uh board. It's a digital board, um, primarily, so it shouldn't matter too much. But yeah, they determined that.

yeah, that was the best course of action is to return the uh ground from the thermal printer. So all the power so the power and data comes in here. but they're using this wire as the return ground path. Neat.

and they've done this right. Look at this big ass. Earth Strap going across here like this over to the main plate up the top. all nicely crimped and screwed into place.

and ah yeah, that's yep. Earth in on this thing's Done Right Aha that ground Return A bodge. afterthought. Look at this.

they're obviously skipping so they need an extra low impedance path from there to there. and they've bodged on this connector. Which is that return ground? Oops. Found that.

Oh, they designed and built the thing and then found that oh, they were getting some issues with their board and probably scratching their head for a couple of weeks trying to figure out what was going on and then some poor bastard Chas traced out the ground and uh, well, there's an internal ground plane in here. but then TR they're probably getting some excess ground bounce on there or something like that when this printer operated this thermal printer and uh yeah, they decided Well to fix it. Well, we're not going to respin all of this this are we? no and have ah separate return pass on the inner planes and stuff like that. No buger that we'll just put a um, we'll just put some extra low impedance path in there and then just return this to those spare pads that they had on that power supply.

a All right. I Was going to say it was well engineered. it's a bodge now. I Guess it depends on what you're into but I personally wouldn't save that thermal printer module I Can't think of a a good use for that.

There's a little contact switch down in there. There we go. that's neat. Um yeah, I don't know.

Not really worth salvaging. I don't know if uh, if you guys do actually keep uh, something like this when you, uh, tear us apart, tell us AP part and tell us why. um but yeah I know the answer because I answered it before in that it's for those things you can't think of, right? All right, we'll hold it. Caution: Do Not touch the flat oval plate.

what's under here? ooh SC a nice little stepper motor out of that. Yeah, that's a keeper that goes in the motor box and there is the thermal printing head on this thing that's the uh header that connected up to it and uh, you can see that they got some drivers gunked down on there, some chip on board stuff happening down there and I'm not sure how many uh pixels. if that's the correct uh turn across there that one is I might be able to get the macro lens on that. oh wow, look at that We can see it There we go.

You can see the individual lines like that. Look at all those fine traces. I Can barely see this on the LCD screen of my camera. It'll probably show up really well in full.

HD You can see that each one of those chips drives. However, if anyone's keeping count, there drives however many uh dots on that uh, on that thermal head there so you can see the chip all gunked up inside there. But yeah, it' be interesting to uh, get a data sheet on one of those uh, driver chips, that's for sure. H So there you have it.

That's inside one of these thermal printers and they're rather interesting I Haven't had a look at in detail inside one of these things before, but uh, fascinating stuff. If anyone does have any data on these things and uh, please share it and this one's fancy. pancy. It's got a paper cutting mechanism on top I Just prized that open and there's the there's the paper cutter there.

It's angled to, uh, slice more easily through the paper and that's just driven by this. uh Worm Drive here on this motor. Nice. So no, you know the cheap ones will just have like a perforated Edge on the outside where the motor just spits the paper out and then the user has to tear it off.

this one actually Cuts your receip for you actually I'm rather inclined to keep that as a complete mechanism like that, cuz it's not often that you'll be able to, you know, get something that just shears off something like that based on a motor input. So yeah, Hm, anyone got any creative uses for that? So there you go: I hope you enjoyed that tear down. Tuesday and even something mundane as a cash register. Um, you know contains them.

You know, some fairly, uh, decent processing and you can salvage some nice parts from it. You get a couple of Motors You get a cutting mechanism, nice vacuum fluorescent display that's just beautiful. a nice reusable uh 128 B 64 dot matrix display a power supply. nice little power supply you can reuse main switch mode job.

well worth the Salvage So there you go. As always. Uh, the data sheets for the things I found in this will be linked in down below. So check it out and if you want to discuss it, jump on over to the E EV blog.

Forum Or you can always leave a YouTube comment. Yes, I Do read all the comments or you can leave a comment on Eev Blog.com However, you prefer to do it I Do read virtually all of them and I try to respond where possible. By the way, Um, if you do want me to respond to your comment on YouTube or wherever generally within like the first 24 or 48 Hours of uploading the video, I'm going to be checking the comments on that video so you know there's more chance that I'm going to reply there anyway. I Hope you enjoyed that and if if you did, please give it a big thumbs up.

Catch you next time.