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Salvage It! By BRUCE PIERSON Harvesting Old Printers for Parts You were cleaning out your shed and you found that old Dot Matrix Printer that you bought brand new in 1995 and retired in 2002, when you bought a shiny new – and colour – USB printer. It’s been gathering dust all that time and it looks like something was dropped on it, because now it’s got a broken lid! Time to bin it? W ell, maybe there’s some good parts inside it, so we’d better have a look and see what we can find before we toss it out. Now to pull it apart. But where do we start? Well, that depends on which brand of printer you have. First, remove anything that can be easily taken off, such as ribbons, covers, lids, paper feeders and the like. Turn it upside down and give it a shake to see if anything else can fall out! Now we can inspect the unit to see how it’s held together. Some printers might have screws on the top, others might have clips underneath, or there could be combinations of these methods of holding it together. In the case of screws, it’s just a matter of undoing as many screws as you can find and then seeing if the two halves of the printer will separate. With clips, you need to determine how they are undone and then undo them. Sometimes manufacturers develop fiendishly clever methods of disguising just how to do it. But siliconchip.com.au eventually, you should be able to separate the two halves of the printer and see what’s inside it. Look, if all else fails don’t be scared to don a pair of safety glasses and try some “percussive service” – ie, belt it with a hammer! Only destroy as much as you need to – you’re going to junk the case anyway . . . The above printer very sportingly had four screws on the top and was easy to get apart. It’s a Star NX1000 which was a very popular printer in its day and is still used in countless numbers even today due to its reliability. But it is “only” a dot matrix printer which many modern users tend to sneer at due to its limitation in printing pretty pictures! However, if you want a printer that handles multipart forms, though, you’ll find it very difficult to find one that out-performs the old dot matrix! How does it work? The inner workings of April 2014  53 immediate need for things like the stepper motors, but hang on to them anyway, because you never know when an electronics magazine will feature a project using a stepper motor and you are unlikely to find stepper motors elsewhere easily. The power supply is probably capable of about 1A from each output. The 5V output can be used as-is and the 25V output can be regulated to supply lower voltages. It would of course need housing in a suitable box to make it safe. In its present form, it is dangerous to use it, due to the 230VAC present under the PCB. So, with a little effort, you have a nice little power supply, and who can’t use another power supply? Another one! dot matrix printers are very similar, irrespective of the manufacturer. Basically, there is a roller, which the paper wraps around and there is a print head which has tiny hammers which strike the ribbon, which in turn puts an image on the paper. The ribbon can be about the same width as the paper or in some cases it’s a small compact type. The print head runs on one or two guide rails and is moved to the right spot by a stepper motor. A second stepper motor rotates the roller, which feeds the paper into the printer so it is at precisely the right position. All these processes are run by the controller. The controller and the stepper motors are supplied with power by the power supply. With the top removed, it’s usually just a matter of undoing screws and taking parts out until the printer is in pieces and you can assess what you have from the exercise. This particular printer yielded the following parts: 1 small power supply with output voltages of 25VDC and 5VDC in working order, 2 stepper-motors with some gears and a belt, A roller and several rods & bars, A handful of screws, washers & circlips, a magnetic reed switch, an optical sensor, The two PCBs contained a variety of following parts, which can be removed as needed: 1 27C512 EPROM 1 28 pin IC socket 1 piezo buzzer 11 medium transistors, 3 small transistors 4 resistor networks 12 ceramic capacitors, 9 LEDs 1 4 way DIP switch 1 8 way DIP switch 1 M50734SP-10 Microcomputer (We covered ways to remove small components from PCBs destined for the bin in December 2013 “Salvage It”). So, what can we use these parts for? The stepper motors can be used in robotics and other projects and the other hardware may have many uses. You might not have an 54  Silicon Chip Not long after I finished wrecking that printer, I was talking to my neighbour and he mentioned that he was having a cleanup and found an old Panasonic Dot Matrix Printer in his shed (deja vu?) and was about to throw it out. Instead, he retrieved it and gave it to me. He’s happy to have the extra room in his bin to continue his clean-up and I was happy to get something else to wreck. Well now, let’s see how we can get this unit apart. Looking at this particular printer, there are two clips underneath that hold the top on but they are reluctant to co-operate. I have reached a stalemate. Well, maybe removing the front panel will help. I resorted to the method I mentioned earlier: donning leather gloves and a face shield and grab my hammer to smash the font off. Surprisingly, it somewhat easily came off in one piece with very little damage. It’s the inner parts that are of interest, so I was careful not to damage them! Now I had access the clips, which when unclipped, allow the top to swing back and come off easily. Now, after undoing a heap of screws, all the various useful bits and pieces have been released and can now be collected and stored for later use. This particular printer has an integrated power supply/ controller on the one PCB and not a separate power supply like some other brands of printer, so it’s a case of grabbing the individual parts. The exact layout inside a dot-matrix printer will vary, depending on the brand but a similar range of components can be salvaged from these otherwise unwanted items, before they become junk filling up landfill. The pity of it is that, like most of the TV sets and monitors you see at the tip or in council cleanups, they often work perfectly. That’s progress, I guess. It’s always handy to be able to get useful items from obsolete and dead equipment before it’s binned, because a lot of the components they use simply aren’t available anywhere else these days, with modern equipment using a whole different range of components. So if you need an “obsolete” part, where better to get one from than an obsolete device? Here’s what usable parts were inside this particular printer: 1 Transformer with secondaries of 29V at around 2A and 10.5V      at around 0.5 – 1A siliconchip.com.au 1 mains filter 1 mains switch 1 mains cable with plug 4 200V 2A diodes 2 stepper motors, one of which was kept intact with its      drive belt and bracket 3 rods 1 bar 2 brass bushes 3 limit switches 8 lengths of hookup wire (7 White, 1 Red) 2 multi-wire ribbon cables 2 lengths light wire with terminals 2 optical Sensors Several gears and rollers Several springs A pile of self-tapping screws and a few machine screws, The three circuit boards contained the following components for later removal, if and when I feel the need! 7 rectangular LEDs (6 green, 1 red), 2 large electrolytic capacitors, 4 tactile switches, 4 small electrolytic capacitors, 27 ceramic capacitors, 8 small transistors, 6 medium transistors, Several different ICs, 1 6-Way DIP Switch, 1 piece smoke-coloured perspex (lid), Plus a few other small components, which may be worth salvaging, if you need them. That transformer looks like it will be very useful to make another small power supply. There’s even four 2A diodes to go with it and two good sized filter capacitors. That will save quite a bit of cash in the construction process. You just need a regulator and a few other bits and pieces and you have another good power supply for little cost. Overall, another very worthwhile exercise, yielding a good range of components for the junk box, which would have otherwise gone to waste and added that little bit more to landfill. These parts now take up a lot less room than what the intact printer did, so storing them is less room-consuming than finding space for the whole printer. SC Increase talk time. Instantly charge your iPhone, iPad, Smartphone, eReader, Bluetooth headset and more! e on h p art ge* Sm char * Based on 5200 mAh model www.verbatim.com.au www.verbatim.com.au siliconchip.com.au April 2014  55