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SERVICEMAN'S LOG Sorting my quake-damaged workshop I absolutely love test equipment and have recently been given some very nice test gear by a friend who’s just retired. Fortunately, I now have somewhere to stash this gear, having just got my quake-damaged workshop properly sorted out and functioning again. O NE THING that makes being a serviceman so much fun is that we get to have a cool workshop to hang out in. There are as many different workshops as there are servicemen and I always find it fascinating to take a look at the workshops of other people I meet in the industry. I especially like to check out what tools and gadgets they have, to find out whether similar tools could be used in my workshop to make my job easier (or would just be cool to have). 54  Silicon Chip A good friend of mine, who was involved in 2-way radios, has just retired and he and his wife are now looking to down-size the family home into something more manageable for a retired couple. And that means he must clear out his workshop. His man-cave is a particularly interesting place for me to visit. His hobbies have involved all things to do with radio and his collection of radiocontrolled aircraft, especially rotarywing models (helicopters to the uninitiated), is quite impressive. To say that this guy’s single-garagesized workshop is packed to the rafters would be an understatement. Choppers and fixed-wing models in various states of repair hang both above and below the rafters, requiring those of us taller than about 5-feet 5-inches (1.65m) to walk slightly stooped to avoid taking out an eye out on an errant skid or a piece damaged landing gear. The floor is covered with pretty much the same blend of models, half-built kit-sets and associated gear. All that’s left uncovered is a well-beaten path from the door to the light-switch and to the equally-cluttered workbench. The single light bulb (an energysaver that takes 10 minutes to warm up) casts a yellow glow over the scene and this and the associated shadows Dave Thompson* Items Covered This Month • • • • • Dave finally gets his workshop functioning again Faulty Sunbeam Retro KE5200E kettle Deckel FP4 CNC milling machine Maison vacuum cleaner Faulty Zen-on Justina guitar tuner *Dave Thompson runs PC Anytime in Christchurch, NZ. Website: www.pcanytime.co.nz Email: dave<at>pcanytime.co.nz add to the atmosphere. It’s no exaggeration to say that I love it there and I’ll be very sad when he down-sizes to some tiny shed that I guarantee won’t have anything like the feel of this haven. However, there is a silver lining; Keith has had to get rid of his old scopes, frequency counters and other flashing-light-infested test gear and, in the spirit of friendship, he kindly offered to give some of these instruments to me. The deal is that I can be their guardian for as long as I want them and for as long as he can come over and use them if he ever needs to. Since he hasn’t used some of them for a few years now, it’s unlikely he’ll ever take me up on that but that’s OK; I’m happy for him to come and use my facilities any time he likes. So far, I have been given a digital oscilloscope (an older, 60MHz dualchannel monochrome model) and a top-quality 20MHz CRT scope, both of which are in excellent working order. They really do look great on my shelf along with my existing scope and various multimeters, soldering stations and power supplies. I admit it; I love test equipment and if I won the lottery I’d have the best spectrum analysers, audio generators, siliconchip.com.au frequency counters and all manner of other suitably-adorned boxes stacked from bench-top to ceiling. The beauty of having this equipment is learning how to use it to better do my job and enjoy my hobby, the two curiously crossing over more often these days. I’ve already put the scopes to good use and I’m now looking forward to taking possession of a very nice AF/RF frequency generator/counter that’s next on the list to go from Keith’s workshop. Quake-damaged workshop Some years ago, my own workshop, which is about double-garage sized, was rendered a complete disaster area by the swarms of quakes we had here in Christchurch five years ago. Prior to those cursed quakes, I had a lot of stuff neatly set up in cupboards, on shelves and in drawers and other storage units all around the walls of my workshop. This “stuff” included small bucket-sized bins of resistors, capacitors, diodes, transistors, ICs and other components one tends to accumulate over 40 years of hobby and professional electronics work. These parts were all neatly arranged and stored in their own compartments and trays until 12.51PM on the 22nd February, 2011, wherein the shelves, drawers and cupboards were literally torn from the walls and everything in and on them ended up dumped onto the workbenches and floor below. The benches run around the entire workshop at a height of 900mm, with gaps only for the entry door and a couple of larger machines along the back wall. During the subsequent aftershocks, of which there were many, everything else that lived in racks, drawers, shelves and boxes under, on or around the benches also ended up on the floor, along with my lathe, drillpress, sander, band-saw, scroll-saw and electronic test gear. I almost cried when I first opened the door but soon forgot about that because my lathe had fallen across the doorway, preventing it from opening properly. The lathe had also taken out a tall metal cabinet of drawers that lived next to it. Fortunately, all the drawers (A4-sized and full of lathe tools, components, half-finished projects and other electronic bric-a-brac) had fired out into the middle of the room, so they avoided getting crushed. However, their contents added to the pile that now covered most of the workshop floor. siliconchip.com.au I initially surveyed the damage through the gap in the door and after checking nothing was on fire and that the workshop power was disconnected (fortunately, the mains were off and would stay off for another 20-odd hours), I locked the door and vowed to sort it all out later. It took about a year to get the workshop into some semblance of order, which basically meant I could walk around most of it. It was still a right mess though and remained like that for another few years as our focus was on other things. Besides, with on-going after-shocks, there was an air of “why bother?” about it all. It was a terrifying time and I didn’t want my epitaph to read: buried in his workshop! As a result, my workshop space became a little-utilised repository for anything that didn’t fit in the house, or was too valuable to leave in the often-open garage that fronted the workshop itself. My workbenches, which had been clear and organised, were now covered entirely in stuff and if I wanted to do anything, I had to literally push things aside until I had room for the new job. Over the years, I chipped away at clearing it up by doing things like sorting out the resistors from the capacitors and then separating other components – no easy task when literally thousands had been mixed together into a scrambled and hard-topull-apart pile that would likely have filled a bathtub. Part of me wanted to just toss the lot and start again but the miser in me prevented me from tossing perfectly good components. It took quite some time to sort it all out and I while I was at it I also separated the electrolytics and tantalums from the non-polarised capacitors and sorted miscellaneous items like terminals from screws, nuts and bolts. One of the most frustrating jobs involved separating about 200 assorted springs from all the other bits; they gripped and grabbed onto everything and I very nearly just chucked the lot but decided against it after considering how long it took me to accumulate them (and how handy they can be). Once I had all that small stuff squared away, I began looking at shelving and other storage options that wouldn’t be susceptible to falling down in quakes. A lot of bits and pieces originally lived on shelves around the walls but I now had to find homes for them in drawers and other solid storage options. We haven’t had any sizable aftershocks for the last 12 months (touch wood) but I’m reasonably confident the storage I now have will take anything up to and including a quake that would drop the garage. And if that happened, I’d have bigger problems than sorting out some resistors! At least we don’t have to worry about bushfires, which would be absolutely terrible. Give me a quake any day over fires (well, a smaller jolt at least). To chuck or not to chuck Over the recent Christmas break, I March 2016  55 Serviceman’s Log – continued D. A. of Shepparton, Victoria recently encountered a string of faults in an old Deckel FP4 CNC milling machine. Here’s how he got it going again . . . Earlier this year, I was asked by a relative if I’d have a look at one of his CNC milling machines. The machine in question was a Deckel FP4 unit from the mid-late 1980s and it had developed a fault in the CNC console. I’m no expert when it comes to engineering but I’ve spent many years repairing electronic/electrical and mechanical equipment, both as a career and as a hobby, and so I thought “why not?”. CNC stands for “computer numerical control” and a CNC mill/lathe has a computer console which allows the user to push buttons and enter commands to drive the machine’s servos and motors. These in turn control the movement of various tools and/or the job itself in the machine to achieve the desired cutting and turning, etc. The story starts when the machine began displaying an FP00 error code which, according to the manual, indicates an emergency shut-down, tripped overloads and/or pressed emergency stop buttons. The first step then is to check the overloads and emergency stops and in fact the owner had already done this but had found nothing amiss. My first thought was that a power supply fuse had probably blown or the supply itself was faulty. When I took a look inside, I found that a fuse had indeed blown. I replaced it and the console came back to life but there was no vertical sync, thus causing the picture to roll continuously. However, I was told that the vertical rolling fault had been there for some time and that the picture stopped rolling after the machine had warmed up. And indeed that turned out to be the case. What was encouraging was that there was no longer an FP00 error on the display. However, the unit still refused to work. Thankfully, the owner has the operator’s manual and the service manual for the machine. Unfortunately, the service manual is printed in German (since the machine is German-made) so I spent quite some time going over the circuits diagrams and checking for continuity in the emergency stop circuit. Eventually, I found that a track on the circuit board had been burnt off. Fixing this cured the fault with the emergency stop circuit and the machine worked again. However, I was puzzled as to what had caused the fault, as it appeared that the circuit board track damage would have been caused by an inadvertent short. The next day, the FP00 error was back so I again checked the emergency stop circuit and found that it was functioning as intended. The FP00 fault code can also mean that one of a few overload circuit breakers had tripped, so I now turned my attention to those. These were all intact so I consulted the circuit diagrams and after some time found that these overload circuit breakers are 3-phase with an auxiliary contact. This auxiliary contact is used to relay the fact that one of the circuit breakers has tripped, thereby halting the machine and bringing up the FP00 code. I soon found that one of the wires going to one of the auxiliary contact’s terminals had been clamped mostly on the insulation rather than on the copper wire and a quick check with a multimeter confirmed no continuity. I re-terminated it and the problem was solved. This was probably a manufacturing defect, the wire just touching the terminal for all those years before it finally went open circuit. In the end, it was a very simple fault but it wasn’t easy to find. Of course, that left the vertical rolling fault but because it quickly disappeared as the machine warmed up, we decided to leave it for the time being. That situation didn’t last long because as winter came on, the vertical rolling fault got progressively worse. Eventually, it was taking around five hours for the display to stop rolling after the machine had been switched on. Having worked on many CRT TV sets, I was fairly sure that this wouldn’t just involve adjusting the internal vertical hold control. Instead, the nature of the fault suggested component drift and I suspected faulty electrolytic capacitors due to the age of the unit. Armed with the circuit and an ESR meter, I checked all the electrolytic capacitors on the deflection/HV circuit board. Most of them measured open-circuit which wasn’t surprising after 30 years or so of service. I replaced the lot, then reassembled the console and switched the unit on. The picture was now locked solid and that finally cured the annoying rolling problem. That wasn’t to be the end of the sto- finally got onto the home straight with the workshop. I spent around three hours each day that I was off work sorting out what I wanted to keep and what I wanted to chuck. I’ve mentioned before that while I’m not a pack-rat, I do tend to gather items that could come in useful for my servicing work. However, I had to modify my philosophy with this clean up. My criteria before starting the clean-up was: will I conceivably ever use this item; yes or no? If “no”, the item went into a rubbish box. I also asked “do I really need this item”? Again, if the answer was no, the article went straight into the bin. It was actually quite liberating to get rid of the junk and tidy the workshop; I’d had some of that stuff for so long and the workshop had been such a mess that it hung over me like a black cloud and I dreaded going in there. In fact, there’s a book currently sweeping the USA about the very subject of getting rid of unwanted clutter and how life-affirming it can be. In this book, the author poses the question: does this item “spark joy” in my life? If it doesn’t, out it goes. While I liked my criteria a little better and thought it a little more practical, it was interesting that I had much the same experience while cleaning out my workshop that this person wrote about. At the same time, I quietly Deckel FP4 CNC milling machine 56  Silicon Chip siliconchip.com.au ry though. A couple of days passed and, much to my frustration, the Deckel FP4 again had a problem. This time, it was tripping one of its overload circuit breakers as soon as there was any attempt to start the hydraulic pump motor. Apparently, this machine uses hydraulics to actuate some of the bed axis movements but I’m no expert on how the whole machine works. In this case, an FP02 error code was appearing on the console. The manual was quite helpful here because it stated that an FP02 error code meant hydraulic pump overload and this indicated the relevant overload breaker to check. It was tripping the overload at switch-on alright and my first thought was that the pump/motor may have seized or something along those lines. The only other option would be a power issue. Sure enough, when I checked the mains voltage on each phase at the overload circuit breaker with respect to ground, two phases were at 230VAC while the centre measured just 63VAC. Three-phase motors don’t appreciate a missing phase and will draw lots of current and generally refuse to start. I then did the same measurements at the 3-phase power point for this machine only to find the same readings. So we had a power issue, rather that a fault in the machine itself. When I inspected the main switchboard, I discovered that the machine was on a circuit with individual phase fuses rather than a 3-phase “ganged” circuit breaker. In the end, it was a simple case of removing the blown centre fuse and replacing it. Once all three phases had been restored, the old Deckel CNC machine operated normally once more and should live on for many more years. cursed the fact that I hadn’t thought about writing a book about it. It could have made millions of dollars, which of course would enable me to buy even more stuff to fill my workshop with! Perhaps it all worked out OK after all . . . After dumping/recycling 350-odd kilograms of rubbish from the workshop, I had a lot of spare space left over. It now feels great to be able to walk to any part of the bench and have room siliconchip.com.au to work on it without having to move stuff around. The best thing about it is that it’s a proper workshop again and I’m not embarrassed to show people around without making lame excuses as to why it was such a bomb-site. While I could legitimately claim it was caused by something beyond my control, it certainly wasn’t beyond my control to tidy it properly long before now. Of course, it didn’t take long for someone to ask me if I had something that I’d just chucked away! It had been in my workshop for years but hadn’t met my criteria for keeping it. The fact is, this will happen every so often and I’ll just have to live with it. The kettle carks it Another thing I’d gotten rid of was a kettle we’d replaced a few years ago with a nice new “digital” model. There was nothing wrong with the old one; it just didn’t colour-match our new toaster so, of course, it had to go. And so, after all those years in the workshop, out it went to the recycling station, no doubt to eventually turn up in one of those eco-shops for a few dollars. I mention this now because just the other day Nina pushed the power button on our kettle to boil some water. As she did so, it gave a nasty electrical “pop!” and its LED display went dead. And so, being a serviceman, the first thing I did was grab it and withdraw to my now-tidy workshop to find out what was wrong with it. “It’s probably just a fuse or something just as simple,” I said to Nina as I made off with it. Yeah, right – fam­ous last words, as many servicemen will no doubt confirm. After negotiating the usual annoying security-type screws and removing the base of the kettle, the electronic gubbins were revealed. No simple switch, thermostat and element for this kettle; instead, inside was a PCB assembly that wouldn’t look out of place in a GPS unit or a portable radio. The top side of the PCB carried a number of parts and a 28-pin IC, most likely a microcontroller of some description. This side appeared to be OK, so I then had to remove quite a bit of plastic mounting hardware and unplug various peripherals such as thermostats, wiring looms for the display and the element wiring in order to gain access to the underside of the PCB. As soon as I flipped it over, the cause of the “pop” was all too obvious; four very blackened surface-mounted diodes and at least one transistor (or similar SOT-23 type component) were clearly damaged. A quick search with Google confirmed my assumption that there would be nothing like a circuit diagram floating around for this appliance and with all active components sanded or with their part numbers otherwise obfuscated (thanks manufacturer), this was likely going to be another guesswork fix. And so, for the time being, I’m stumped. If anyone out there in SILICON CHIP “reader-land” has a circuit diagram for a Sunbeam Retro KE5200E kettle and is willing to share it, please contact me. The rest of the board appears to be in pristine condition, probably because the whole thing is covered in some sort of soft, clear “goop” to water­proof it. This goop had melted away from the dead components, making it easy to access them, but I suppose any “fix” will require a similar covering once done. I’ll use epoxy resin. I think – should I succeed in getting it going again, that is . . . All the failed components surround a relay whose contacts switch mainslevel voltage to the element, so I’m wondering if the relay has shorted or something similar. The output track of this relay has been damaged so it’ll have to be replaced too. The diodes shouldn’t be a problem; the silk-screen at least is very clear as to polarities etc and they look like 1N4001s or similar for rectifying AC to DC for the rest of the circuit. The SOT-23 “transistor” may be a regulator and if I can’t get a diagram, I’ll try to “reverse engineer” this part of the circuit and draw a diagram. That way, I might be able to figure out what this part does, so that I can March 2016  57 Serviceman’s Log – continued Identifying some of the charred parts on the kettle’s PCB will be extremely difficult without a circuit. try to replicate it. Finding another relay should be simple enough too; the manufacturer has kindly left the part numbers intact so if I can’t locate the exact one, any similar 24V DC, 16A relay that fits the board layout will do the job. I’ll let you know how it goes. In the meantime, we went looking for another one of those kettles but they aren’t sold any more and the new ones either seem cheap and nasty by comparison or don’t match the rest of our kitchen appliances. We’ve settled on “cheap” for time being in the hope that I can get the faulty unit going again. But whatever happens, at least I’ve once again got a pristine workshop in which to work. It really is a much more pleasant place to be than before the big clean-up. Maison vacuum cleaner Regular contributor B. P. of Dundathu, Qld has no particular love for vacuum cleaners. But why chuck out old faithful when you can fix it yourself and save money into the bargain? Here’s his story . . . Our middle (teenage) son had been doing some vacuuming (yes, really!) 58  Silicon Chip when the machine suddenly started making a loud rumbling noise. Not wanting to risk further damage, he turned it off straightaway and I decided to check out what the problem could be. My first test was to turn the vacuum cleaner on and then off again quickly, so that I could briefly hear it running. We’ve had this vacuum cleaner for quite a long time and I had already repaired it several times previously. I’d also fitted new brushes to it around 18 months ago. This time, however, I wasn’t sure if it was repairable, because it sounded like the bearings were shot. The brushes were also arcing badly, which could indicate that the armature had shorted turns. Despite this, I decided to delve deeper and find out just exactly what the problem was. I started by dismantling it and I initially checked the brushes. My suspicion was that they may have been poor quality and had worn down already, as the cleaner had had a lot of use since I fitted them. However, they were fine, with plenty of “meat” left on each one. I then noticed that the rear bearing next to the commutator had blue marks on it, indicating that it had been running very hot. This wasn’t looking good! After some further dismantling, I had the armature free and I could then assess the situation more thoroughly. This revealed that the rear bearing had virtually disintegrated – the plastic retainer that keeps the ball bearings correctly spaced was no longer present, the metal shield on one side had fallen off and the rubber seal on the other side had also fallen off. At that point, the bearing literally fell apart and the ball bearings dropped onto the ground. I also noticed that the metal shield had been distorted, which indicated that the bearing had been running out of true. Because the armature would have been moving around so much, this could explain why there had been arcing on the brushes. I then checked the front bearing and found that it was only slightly worn. Even so, I decided that I would replace both bearings and this is where I ran into difficulty. My automotive bearing puller was just too big to remove the front bearing and it would not grip the inner race of the rear bearing. As a result, I decided to reassemble the rear bearing, so that it would have a larger area for the bearing puller to grip. I retrieved the ball bearings, greased them and placed them in the outer race, then put the inner race back in. After turning the bearing, the individual ball bearings distributed evenly around the unit and I was able to use the bearing puller to remove it. That done, I turned my attention to the front bearing. After some thought, I decided that because it wasn’t badly worn and because I couldn’t easily remove it, I would simply service it and leave it in place. First, I removed the outer metal shield to access the inside of the bearing. It had some dirt in it and the balls were devoid of grease, so I cleaned it using a pressure-pack can of multi-purpose spray and then blew out the remaining liquid with an aircompressor. I then searched for some suitable grease. Because I do my own vehicle and equipment servicing, I have a variety of greases on hand. In the end, I chose some automotive “no melt” disc brake wheel-bearing grease, as this would be ideal for the purpose. After greasing the bearing, I refitted the metal shield and then noticed that there was some wear on the commutator. This was fixed by “dressing” it with a fine file. I knew the rear bearing would be under $10, so it was worth taking a risk and replacing it. As it turned out, it cost less than $5 from a local supplier. Once I got it home, I set about re-assembling the vacuum cleaner and when I had the motor back together and in place, I decided to give it a run before re-fitting the cover. When I turned it on, it ran smoothly without the rumbling noise but there was considerable arcing from the brushes. I was begining to think that the motor might be on the way out when it suddenly picked up speed. At the same time, the whine it made increased in pitch and it sounded “smoother”. When I looked at it, I immediately noticed that there was no further arcing from the brushes and it was running nicely. I can only assume that the initial arcing had been caused while the brushes “bedded in” again. Who knows how much longer it will continue working but while ever I can continue to repair it and keep it going, I will do so. This repair cost less than $5 siliconchip.com.au and saved yet another defective piece of equipment from going unnecessarily into landfill. Of course, this type of repair would not have been taken on by a service agency. The cost of the labour alone would have comfortably exceeded the price of a new vacuum cleaner. It’s really handy to be able to do this type of repair myself and save our family quite a bit of cash in the process. Faulty guitar tuner A. C. of Clarement, Tasmania recently repaired an ancient guitar tuner that had no less than three faults. Here’s how he got it going again . . . One of the challenges of being someone who “knows about” electronics is that all your friends and associates know you’re the guy to send their paraphernalia to for a quick check-over when it’s not working. Recently, I was handed a cheap guitar tuner from my wife’s employer (“your husband can fix stuff, right?”) with the highly-detailed diagnosis that it was dead. The unit turned out to be a Zen-on Justina Quartz Guitar Tuner, with a 3-position switch to power the unit and check the battery level, a 6-position switch to select one of six string pitches, a moving coil meter to indicate the battery level and tuning of the guitar, a built-in mic to allow tuning acoustic instruments and a 1/4-inch socket on the side to accept a connection from an electric instrument. The case was made of plastic in a garish 1970s orange colour but despite its apparent age, it looked to be in pretty good shape. In fact, the Justina reminded me of my first guitar tuner which had been given to me for Christmas about 25 years prior. Its fam­iliar control layout suggested that it was some kind of generic design that had been produced over the years as a budget alternative to the more expensive tuners made by companies such as Boss and Peterson. After sliding off the 9V battery cover it was a no-brainer to work out why Servicing Stories Wanted Do you have any good servicing stories that you would like to share in The Serviceman column? If so, why not send those stories in to us? We pay for all contributions published but please note that your material must be original. Send your contribution by email to: editor<at>siliconchip.com.au Please be sure to include your full name and address details. the unit was dead. The battery clip was missing, with only the red and black wire entrails hanging out of the compartment. This was going to be easy! I rifled through my parts drawers and extracted a 9V battery clip of a vintage that complemented the retro orange duco, de-soldered the two wires from the PCB and refitted the new clip in their place. I then managed to find a 9V battery with enough zing in it to pass the lick test and clipped it into the tuner. Flipping the unit back over, I moved the first switch to the BAT position and was encouraged to see the needle rising to the lower end of the “Good” mark on the meter. I then slid the switch to the ON position, selected the A-string pitch and did my best impersonation of a chorister at what I thought was about 440Hz, but the meter’s pointer failed to rise off the lefthand end-stop. My first reaction was that the tuner was simply being judgemental about my dulcet tones, so I tried a few different pitches on the pitch selector switch, again with no success. I then connected a guitar to the 1/4-inch input socket but this also failed to elicit a response and after confirming that both the cable and the guitar were OK on a known-good tuner, I realised that it wasn’t my singing that was the problem! I opened the case again and had a careful look for any dry solder joints. This quickly revealed a fractured joint on the 1/4-inch socket and I surmised that both the microphone and guitar signals passed through this socket, with the microphone signal being bypassed when a guitar was connected. After re-soldering this joint, I turned the unit back on and checked the response with my voice and a guitar but the meter still refused to move. Disassembling the tuner for a third time, I re-inspected the PCB for any further dry joints that I may have missed. I found a couple of narrowly-spaced pads near the new battery clip pads that looked a little frosty but I didn’t think they were bad enough to cause trouble. Even so, I re-flowed these pads with fresh solder as well. Curious to know what was on the other side of the board, I flipped it over and had a look at the device connected to the pads I had just re-flowed. It turned out to be a 78L05 5V regulator but there appeared to be some kind of strange mark on the front of its body. On taking a closer look, I realised that the mark was in fact a crack that had split the regulator right down the middle. I duly replaced the damaged regulator and reassembled the guitar tuner for what I hoped would be the last time. And that was it – this time, when I connected a guitar, I was at last rewarded with the pointer springing up to the middle of the dial when I ran the pitch tests. A quick whistle test confirmed that the microphone also worked. It also confirmed that my initial assessment of my vocal abilities wasn’t too far off the mark. I can’t imagine what caused the 78L05 to fail in such a spectacular way considering that the highest voltage applied to it would have only been from a 9V battery. As can be imagined, the owner was grateful to have the tuner SC back in working order. Issues Getting Dog-Eared? Keep your copies of SILICON CHIP safe, secure & always available with these handy binders REAL VALUE AT $16.95 * PLUS P & P Order now from www.siliconchip.com.au/Shop/4 or call (02) 9939 3295 and quote your credit card number. *See website for overseas prices. siliconchip.com.au March 2016  59