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Salvage It! BY LEO SIMPSON Gather up those discarded monitors now – before it’s too late There is a massive change happening in Australian offices and homes at the moment: CRT monitors are being discarded in their thousands in a wholesale changeover to LCD monitors. This represents a great chance to get a big stock of useful components but you need to do it now because CRT monitors will become a rarity within the next few years. P OSSIBLY YOU HAVE seen lots of monitors being thrown out in the streets during your local council clean-ups. Lots of computers are being thrown out as well. But while the computers themselves might present limited possibilities for salvaging parts, CRT monitors, particularly the older ones, are a treasure trove of good components. Consider also that many CRT monitors being thrown out are still working perfectly. Their owners have simply upgraded and because they don’t want to keep them in the garage or wherever, they are being tossed out. So if you pick up a monitor from a council street clean-up, the chances are that all of its components are still quite OK. Even our own office at SILICON CHIP has made an almost complete switch to LCD monitors during the last year, so we had a good range of old CRT monitors, some dead, some nearly dead (with worn-out picture tubes) and some relegated to standby, just in case a monitor failed and we needed a quick substitute. So we only had to take a few steps out to the warehouse to pick a random candidate for this story. The one we picked was probably well over 10 years old and a very good 17-inch (diagonal) monitor in its day. And it was destined for the tip, along with a couple of very large 2182  Silicon Chip inch monitors and a bunch of others which were dead. I must admit that I hate throwing this stuff out, because I know that it once represented some of the finest technology that money could buy. Now, it is just old stuff that takes up space. Down to work Anyhow, it was out with the tools and down to work. Removing the cabinet back was simple, with just a couple of screws and a few clips to unlatch. Before that though, we pulled off the swivel base which incorporated a USB input and output. We pulled this apart and found a well-shielded PC board which had provision for more inputs – just why it was there was a mystery. However, these were perfectly good USB sockets which could be pressed into service for some future project. Having removed the back off the cabinet, you have to wonder if this might have a use. We racked our brains and could only come up with two possibilities: a waste paper basket or as plant holder in a garden pond. They have a lot of ventilation slots so they cannot be used as conventional plant pots unless lined with plastic; perhaps readers can come up with some other uses. If so, we would like to hear about them. We also removed four screws to remove the front escutcheon from the picture tube frame. This incorporates three small PC boards. One board has two potentiometers (brightness & contrast) with push-on knobs, another board has miniature pushbuttons and the third, the on-off switch assembly, has a miniature pushbutton switch and LED. All of these could be useful to have in your junk-box. Then we pulled the main board off the picture assembly – a few screws and clips did this but it was still tethered by numerous leads to the neck-board assembly and to the picture tube via the EHT connector and earthing leads. Well, there is no need to desolder any other these – just clip them off with side cutters. And what a magnificent resource is the main PC board! Measuring 370 x 290mm, it literally had hundreds of components. Not all are worth salvaging, since it would take too much time and many would be damaged by desoldering. However, virtually all the capacitors can be safely removed as can the relays and a number of toroidal inductors. Heatsinks Many of the discrete semiconductors such as power transistors also have very useful clip, flag and extruded aluminium heatsinks which siliconchip.com.au transistors and any ICs, unless you are able to identify ones that you particularly want. Neck board There’s lots to salvage inside an old CRT monitor, including aluminium heatsinks of all shapes and sizes, trimpots, capacitors, semiconductors and highpower resistors. Don’t forget the tinplate shielding around the neck board. are worth salvaging, even if you don’t want the semis themselves. A lot of the power diodes are mounted with long leads (to give them plenty of ventilation) so they can be easily removed simply by clipping them off close to the board. Also mounted well off the PC board were a lot of metal film power resistors of about 2-watt rating. These should not have drifted much in value so they are probably worth saving too, merely clipping them off the board. The bigger wirewound resistors are also worth removing. Removing the parts To remove the multitude of capacitors and the bigger semiconductors, you will need a large soldering iron, preferably one rated at 60W or more. You don’t want to be fiddling around with a small temperature controlled iron with a small tip – it will take forever to get even a small number of bits off the board. The process here is to heat all leads of the component simultaneously, as quickly as possible. In a previous Salvage-It article, the author suggested using a heat gun to get the bits off PC boards. That is OK if you are being highly selective siliconchip.com.au in getting bits off. But if you want to remove lots of plastic and electrolytic capacitors, the heat gun will apply too much heat over too big an area and while you are concentrating on just one component, others may well be damaged. Remember that each small plastic capacitor you salvage is probably worth an average of 50 cents and the larger electrolytics may be worth quite a few dollars. The main electrolytic reservoir capacitor on the board was a 330μF can type rated at 400V. This is quite a valuable component if you are going to build a high-voltage power supply. If you are into restoring vintage radios you need to grab as many of the capacitors as you can, particularly those with the higher voltage ratings. This main board had dozens of capacitors that were worth saving. If you want a selection of multicoloured hook-up wire, don’t neglect the various cable assemblies. Most of the transformers probably are not worth saving, as they will usually be special high-frequency types with ferrite cores. Also not worth bothering with will be all the small resistors, small plastic Don’t overlook the neck board. This will be in a tin-plate shielding cage and will accommodate an array of wellmade vertical or horizontal trimpots, high-voltage video transistors with big flag heatsinks, more power resistors mounted on long legs and various toroids used for suppression purposes. We would not bother trying to salvage the passive components on the neck board as they will have been subjected to a lot of heat and voltage stress over the years. It goes without saying that any salvaged components should be tested before they are re-used – some might be quite marginal such as leaky capacitors and resistors that have drifted high in value. Some pots and trimpots will also tend to be dodgy, as their wipers tend to make poor or intermittent contact as they get older. So what else is worth saving? What about the degaussing coil around the picture? In fact, the set we dismantled had two degaussing coils, one around the main body of the CRT near the metal frame and a smaller one near the yoke. The larger one could perhaps be pressed into service, together with a plastic tuning capacitor, to make an AM loop antenna (see Stan Swan’s article on this subject in the January 2008 issue). Don’t forget any useful screws, nuts, washers, lockwashers, brackets and other small pieces of hardware. Any metal bits that you are not going to save should go into your regular recycling bin. Don’t hoard too much While you might be keen to save good components, remember that you can have too much of a good thing. Organise your saved bits into parts bins or jars with a marked range of values. There is no point in having lots of recycled parts if you cannot easily access them when you have a particular need. When you have salvaged the parts you need, put the rest in your garbage bin. You can do this with a clear conscience, knowing that you have saved many useful and often expensive components from the tip, to see useful life SC in another application. June 2009  83