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SERVICEMAN'S LOG Smart TVs can be pretty dumb sometimes Dave Thompson* It might surprise a few readers to know that despite constantly teetering on the bleeding-edge of technology in my day job, my home life is surprisingly low-tech. You’d imagine that after 40-plus years of building gadgets and magazine projects from all ends of the hobby electronics spectrum, my home would be bristling with automatically-opening this and clap-your-hands-to-turnoff that. You’d think my car would have reversing bleepers, wiper delay controls, electronic ignition, radio boosters and all that flash kit. While it does actually have those features, none were built by me, rather, they all came standard with the car. In fact, there is very little in my car with my soldering signature on it. What’s the old saying? A plumber’s pipes are always rusty, a cobbler’s children always have bare feet or something along those lines… When it comes down to it, a lot of the gadgets I built in the past have become outdated and were replaced by cheaper and better commercial versions. I’m also what buzz-word fans like to call time poor, in that I have little time left in my day to devote to building projects. After the on-going (and seemingly never-ending) work renovating my workshop, fixing up the interior of the house and trying to run a business, free time is a luxury I don’t presently have much of. The point behind all this is that we don’t have a lot of high-tech appliances and gadgetry at home; we don’t even have our set-top box wired up to watch terrestrial TV, and getting Sky or similar cable TV seems like an expense we can’t justify with the amount of gogglebox watching we currently do. Perhaps we’d watch more if we had all that stuff in place but for just one example, to get that set-top box working, I’d need to re-route the connector and cable from the external TV antenna that the previous homeowner installed on the roof. And that would involve crawling through cramped, humid, spider-web-covered and dusty roof spaces. Given that I’m no longer 20 years old and find it increasingly difficult to mould myself into some of the shapes required to navigate these areas, the cable run and jack point for the TV antenna can stay where it is, on the exact opposite side of the room to where our TV sits. In times past, I’ve rigged a temporary antenna extension cable strung across the carpet in order to both check the socket worked and to test a very funky little set-top box that a very kind, industry-connected serviceman sent to me from Australia to ensure it worked in NZ. But stringing a longer extension cable around the periphery of this room is not feasible, nor is it a tidy long-term option. Joining the 21st century I only mention all this because the other day I saw an offer for joining the streaming internet TV service Netflix and began to think about how that would work in our household. The advertisement listed some up-coming shows that piqued my interest, so I thought I’d mention it to my wife and see what she thought of the idea. Unbeknownst to me, she’d seen the same promotion and mentioned it to me first, so we discussed it and decided to sign up for a month’s free trial and see what all the fuss was about. It all seemed straight-forward enough; my wife mentioned that several people at Items Covered This Month • • Smart TV versus a smart Kiwi Samsung S24D390 monitor repair • Fixing two 750W 230VAC/12V DC GMC generators • Switchmode power supply with a blown fuse *Dave Thompson runs PC Anytime in Christchurch, NZ. Website: www.pcanytime.co.nz Email: dave<at>pcanytime.co.nz siliconchip.com.au Celebrating 30 Years February 2018  57 her workplace were Netflix customers and highly recommended it. They’d simply plugged their smart TV into their local network, signed in using the Netflix app on the TV and away they went. This sounded far too easy, yet it ironically in-part explains why my company no longer has any bread-and-butter work to do. Years ago, we made a respectable living out of setting up clients’ broadband modems and local networks; now customers are supplied modems that are pre-configured to work out of the box. No more setting IP ranges, subnet masks, MAC addresses or default gateways. Nowadays everything is done automatically and is truly “plug and play”. Of course, one gets the odd situation where things don’t quite go so smoothly but typically a phone conversation with the relevant helpdesk soon has the customer up and running, and all without a tech in sight. I signed up with Netflix on their website and once logged in, clicked around it on my computer to check it out. They have a lot of content that I considered worth having a look at, however, as is typical in this day and age, “our” content is different than what they offer subscribers in the USA or the UK (and possibly even Australia). 58 Silicon Chip It appears the same old zoning, monopolising and price-fixing practices extend even to this media broadcast system. Still, there seems to be enough to keep us occupied for our first free month’s trial and after that, we’ll have to see where we stand. All I need to do now is to get Netflix working on my eight-year-old 40” Sony Bravia TV and we will be good to go. Watching a two-and-a-half-hour film sitting at the computer, or worse, on a smartphone screen might be a good night in for millennials, but I’d rather watch anything longer than the average Mr Bean sketch on a decentsized screen and be sitting comfortably in a proper chair. Connecting the TV The first thing I’d need to do is connect the TV to our local network. This means plugging a Cat5 network cable into the LAN socket on the TV and running it to the nearest network switch. Unfortunately, that sits around 15 metres from the TV, as the crow flies (not that we get a lot of crows in our living room!). However, as might be apparent by now, I’m not into running external cables, no matter how carefully hidden they might be and with several doorways to contend with as well, I’d ideally need to run the cable through the roof. I refer you to my previous explanation as to why this isn’t likely to happen. Underfloor is also out so I’m going to need another way. I can already hear the cries of people telling me to go wireless instead. However, Sony was way ahead of me; instead of building WiFi capability into the TV, they helpfully provide the capability for using an external adapter. But I can’t use any old WiFi dongle, I need to buy a special Sony WiFi dongle, which of course costs a small fortune. This immediately triggers my “stick-it-in-your-tail-pipe” response, so I won’t be going down that road. In the meantime, I suppressed my aversion to exposed cabling and laid a temporary cable around the walls. After all, there’s no point in getting carried away with buying hardware or installing anything permanent until we Celebrating 30 Years are sure we’ll stick it out past the free trial period. With the cable plugged into the router and the TV, and all the relevant lights flashing to indicate connectivity, I sat down to see what we had working. Reassuringly, there is an “Internet TV” button on the remote controller, so I started by pushing that. Straight away I ran into a problem. A menu popped up with a selection of options, all of which were not available to select, except one, which was the Bravia Internet option. When I selected it though, after a moment ‘thinking’ about it, a message popped up telling me that I wasn’t connected. After a little more button-pushing on the remote, I found a network setup section, and after running the rudimentary "wizard" was informed that the network was OK, the internet was available and the TV was ready. When I went back to the Bravia Internet menu and selected it, I still went nowhere. But this time I got a message saying I had to register my smart TV with Sony so I could access their internet services. To do this, I’d have to return to my computer and register the TV online. That only took a few minutes, and after entering a code provided by the TV, the set was registered with “my devices” at my new Sony Entertainment account, and the buzz was mounting. We were ready to go! By the time I’d walked back into the lounge, the TV was displaying a message telling me it was registered. This time, when I selected Bravia Internet, a dialogue appeared and went back and forth for a minute or so while I was “authenticated” before an error code popped up telling me I needed to register my Bravia. What the .. !?! After trying a few more times to make sure it wasn’t a temporary glitch, I resorted to the internet. It seems hundreds of people had the same problems and it appeared to be related to the age of the TV. While this model is around eight years old, it’s not as if it’s from 1975; surely it couldn’t be relegated to the heap so soon? Eventually, after much gnashing of teeth and wringing of hands (and the odd swear word), I found a new firmware download for this model of TV. After copying the downloaded file to a flash drive, I put it in one of the two USB ports on the rear of the set and rebooted the TV. The update file was automatically siliconchip.com.au detected and took around three minutes to complete. The set restarted and all the settings had been retained, which was quite good; many firmware updates reset everything to default. In this instance, it didn’t matter because I didn’t have any custom settings in there anyway! This time, when I tried the Bravia Internet, I logged on to the Bravia Entertainment Network and was instantly completely underwhelmed by the choices offered. There was a grand total of five channels available, three of which no longer worked and the others were so lame content-wise that watching paint dry would have been like a summer blockbuster. What a rort… Once again, I hit the web; I was under the impression Netflix would be natively available, but of course, when this TV was made, Netflix was just an idea someone was working on. The firmware was dated 2014, but still nothing there either. According to consensus online, my TV was too old and even though it is a “smart” TV, it is apparently too dumb to receive today’s content. Not to be beaten We had another option, my LG Bluray home theatre system. This device boasted a network socket in the back so I plugged that in and fired it up. Sure enough, there was a Netflix app listed there, so I selected it and waited. And waited some more. After about 30 seconds, I was asked to sign in, which I did, painfully, using the remote control as a text-input keyboard, and then hit enter and waited some more. Finally, Netflix loaded, and I selected a title and hit Play. I then waited for the documentary to load, the status of which is indicated by a progress bar at the bottom of the screen. After about 30 seconds, the bar stopped. After another minute or so waiting, I tried pressing buttons, but to no avail; the system had hung. Luckily, I’d found out how to hardboot this device when working on it once before; like many computers, holding the power button down for 5-10 seconds trips off the power. After restarting it, I tried loading another title. After the same loading wait, it started playing. It seems the progress bar gets to about 30% while it is buffering before starting the media. On the previous try it must have siliconchip.com.au hung just as the title started to play, but this time it did start. However, our joy was short-lived when we started playing with the forward and reverse controls. On the computer, these actions are quick and perform like any other on-screen media-player menu. On the TV, it was painfully slow. It is actually so bad that it is unusable, and our excitement at this stage was turning to bitterness. How did other people get on with all this kerfuffle? Flashing firmware and configuring players isn’t the gold-standard for internet TV surely? The people my wife talked to said they had no worries, or so they claimed. Once again, we felt like we were the only people who had problems with this stuff. To all those armchair techs out there whose heads are swimming with possibilities, let me add some figures; we have a 200mbit fibre pipe into this house, though at speedtest.net our tests consistently achieve readings in the high 90s down and 40 up, so while underperforming, our speed should be more than adequate for streaming media. The Blu-ray player might be a few years old and the TV apparently now pre-historic but I had still assumed that our experience would be better than it was. But I wasn’t done yet. I have a Raspberry Pi and my memory banks had stored the fact that people were using them as entertainment centres. Apparently, all I needed to do was download and run a Linux-based home-theatre software system named Kodi, and I’d be away. This I did, and soon had Kodi running, but once again, while I had a gazillion available add-ons, offering everything from German sports to Arabic news, I had no Netflix, which further research blamed on licensing problems. This was becoming very tiresome and I’d spent a lot of time I didn’t have to spare on getting this thing to work. Then I had the thought of just running Raspbian, the Raspberry-Pi’s normal operating system, and running Netflix on the included Chrome-based web browser. This actually worked, but again not very well; it appears the Pi doesn’t have the processing grunt to run this at high resolutions. With the browser in full-screen mode, any movie stuttered horribly. In windowed mode it was watchable, but who wants to watch a 1024x768 window on a 40-inch screen? While I was trying all this, my wife discovered that some bright spark had found a way of getting Netflix to work with Kodi but it required a beta version, which I eventually found and downloaded. After some more downloading and installation of add-ons, we finally had the Netflix app installed. It even let us sign in, but as soon as I tried to play a movie, it crashed with an error, and further research revealed that I needed another resource called Widevine, a DRM decrypter and well, at this point, I ran out of excitement and concluded that it is just too difficult. Maybe I was over-thinking it. Maybe my expectations were too high. Maybe it just isn’t up to what I would call scratch yet. Regardless, I ended up plugging the cable back into the Blu-ray player and making do with that. I’ve also put an order in for Gigabit internet, which is five times faster and actually cheaper than what we pay now. We’ll see whether that improves Netflix’s loading and fast-forward/ reversing times. I have since read about people using the likes of ChromeCast to relay content from computers, tablets and phones to their TVs but having to do that seems unwieldy and a bit naff. Issues Getting Dog-Eared? Keep your copies safe with these handy binders Are your Silicon Chip copies getting damaged or dog-eared just lying around in a cupboard or on a shelf? REAL VALUE AT $16.95 * PLUS P & P Order online from www.siliconchip.com.au/Shop/4 See website for overseas prices or call (02) 9939 3295. Celebrating 30 Years February 2018  59 To my mind, it should just work, especially if they want us to stay on and pay for it. Technology… when it works seamlessly, it may have the appearance of magic but when it doesn’t, it’s more like having a voodoo curse or a hex upon your head! Samsung S24D390 monitor repair J. W., of Hillarys, WA, is a generous sort and so he recently offered to fix his friend’s monitor, which appeared to be on the way out. Luckily for him, it didn’t turn out to be a terribly expensive or difficult job. Here’s what happened... A pensioner friend recently asked me to look at his 24-inch Samsung LCD monitor. He said the top third of the screen was going dim after some hours of use but was OK next time he turned it on. It was only a few years old and he did not want to throw it away and get another. So I connected it to the Raspberry Pi in my shed and left it running. When I came back some time later, sure enough, the picture was intact but the top third of the screen was dull as if the backlight had stopped working. I found a central screw on the back of the monitor and removed it. I then had to use some plastic prying tools to undo the numerous plastic tabs holding the back on. Inside, I found a small PCB which contained all the electronics with three cables connected to it. One large ribbon cable went to the LCD panel itself, another went to the switch panel on the front of the monitor. The third went to the front of the monitor and when I checked the PCB, the labels indicated they were for LEDs 1-3. So this was for the LED backlight system. As there were only four wires in the cable, I assumed one was for power and the other three were the low-side drive lines for the three sections of the screen: top, middle and bottom. I powered up the monitor again and it performed normally so I traced the tracks from the backlight connector to find three transistors connected to the main controller IC. The output of each also had a resistive divider that sent a portion of the output voltage back to the main controller. So the controller was able to monitor the operation of the backlight system and disable it if it appeared to be faulty. 60 Silicon Chip I measured the voltages on each transistor and found all to be identical. After a short time, not enough for the monitor to warm up properly (especially with the back removed), the top third of the backlight went off. I checked the voltages on the three transistors again and found one which did not match the others. So was the problem the transistor, the controller chip, the connections or the LED backlight itself? I decided to figure out where the fault lay by swapping two wires in the backlight connector that plugged into the PCB. This would move the fault to another third of the screen if the driver electronics were at fault. The fault returned after a short time with the top third of the screen dull as before. This proved the fault was indeed in the backlight assembly and not the controlling electronics. The next step was to try to disassemble the LCD panel and backlight to see if I could identify the fault. The LCD panel came away easily enough once I had removed a number of screws. I was able to hinge it out of the way as there was a flexible connector at the bottom edge. However, once I checked under the panel, I found that access to the backlight system was from the back. Celebrating 30 Years I had a good view of the backlight diffuser and when I tapped the side of the monitor, the top backlight would flicker and eventually go off and come back on when I turned the power off and on. So it seemed the problem was some sort of bad connection and the controller was detecting the problem and disabling the faulty section. I decided to remove the LCD panel entirely to make it easier to access the backlight system. The area around the back of the monitor was again held in place by plastic tabs so a bit of prying with a small plastic tool got it apart. I could now see the diffuser used to spread the light from the side-lit LED system. The LEDs were in a long strip that appeared to be glued to the side of the metal case, so getting at them seemed to be impossible. At this stage, I noticed a 2x3mm piece of metal which moved when I shifted the monitor. It was sitting at the bottom of the string of LEDs. I removed it with a pair of tweezers and decided there was no more I could do to fault find any further at this stage. After reversing the disassembly process and letting the monitor run for a number of hours, the fault did not return. So I have to assume that the piece of metal was sitting in a posisiliconchip.com.au tion where it was occasionally shorting something out and causing the controller to switch that section of the backlight off. I ran the monitor for a few days with no sign of the fault returning, so my friend had his monitor back at no cost. The only mystery was where this piece of metal had come from. Maybe it broke off something else in the monitor. I guess we’ll never know. Two generators for the price of one B. P., of Dundathu, Qld, recently had problems with two similar generators. He faced the typical challenges of sourcing suitable parts but managed to find a valid substitute. In the process, he discovered an interesting design aspect of the alternator. Here is his story... Several years ago, we bought a GMC 750W 230VAC/12V DC generator, which we used a few times initially, including powering a PC with a CRT monitor. It was then put in the shed and not used for quite a few years. Recently, I took it out to use it and I found that it no longer worked. The two-stroke motor ran OK but there was no electrical output from either the 230VAC outlet or the 12V DC outlet. As the generator had been barely used and it was still like new, I was a bit surprised by this. I suspected that it might have stuck brushes as a result of sitting unused for several years. The first job was to remove the fuel tank, which was held on with four bolts. This then revealed the top of the unit and all the wiring. I then proceeded to remove the outer casing from the alternator so that I could check to see what problem may exist. I could find nothing wrong inside. There were no brushes in this alternator, as it works on a different principle to a car alternator. There was a field coil and a wound armature but no brushes, so it was a bit of a mystery to me as to how it actually worked. A car alternator (many of which I have repaired) has brushes (and slip rings) and a regulated field supply from the battery. Despite not fully understanding how it worked, I decided to investigate further. I identified the motor ignition coil and the ignition module but then I spotted what appeared to be a large black capacitor. I removed this capacitor and I noticed a physical defect in it, so this was most likely siliconchip.com.au the cause of the problem (see photo at the upper right). This capacitor was rated at 10µF and 350VAC, so I started looking on eBay for a replacement. At first, I had a lot of trouble finding anything remotely resembling this capacitor, as what was showing up was smaller types that are more common. Then, several pages later, I found what I was looking for but this capacitor was really expensive. However, I noticed that it was called a “generator capacitor”, so I changed my search criteria to that and now I had a lot more of the correct type of capacitor showing up but they were mostly 12µF and not 10µF. I gave the matter some thought and I decided to order a couple of the 12µF capacitors and take a chance that they would work, as they were a lot more common than the 10µF capacitors and a lot cheaper as well. The capacitors arrived, so I fitted one and I tried to start the generator. However, now it wouldn't start. I removed the spark plug and I found that I had no spark on the plug, but I had a spark on the lead. This type of thing often happens with two-stroke engines. I heated the plug with my blowtorch and re-fitted it and then I managed to start the generator but I would need to replace the spark plug later. However, it was running now, so I took the opportunity to test it to see if it was producing any electricity. My multimeter showed that I had 230VAC at the AC outlet and around 14V DC at the DC outlet, so it was now working. I grabbed a bed lamp and this lit when turned on, so I then got out my angle grinder to see if it would work on the generator. This angle grinder has a 625W motor and the generator's rated output is 550W (750W peak). The generator ran the angle grinder OK but it did make the motor work a lot harder. So the 12µF capacitor was fine as a The large black capacitor located in the generator with a fairly obvious crack in its casing. replacement for the original 10µF capacitor. One down, one to go Later, I just happened to be looking for something in my shed and I found another one of these GMC generators which was the same model as the original one. I couldn't remember where this generator came from, but I most likely got it when I helped a friend clean out his shed a couple of years ago and I brought a few “goodies” home. This second generator had no fuel tap; it had broken off and the fuel line had gone hard. I needed a new fuel tap for our original generator too because the handle part had broken, so I ordered a couple of fuel taps and some fuel line on eBay. The fuel taps arrived but I then noticed that the outlet was on the opposite side to the original, so I couldn’t use them. I hadn't noticed the orientation at the time I ordered them but further searching located fuel taps with the outlet at the bottom instead of the side, so I ordered this type and waited for them to arrive. In the meantime, I had a look at the second generator and gave it a clean, as it was quite dirty. While doing this, I removed the capacitor to check it and I found that it was in fact 12µF. This was interesting. I did notice a slight variation between the two generators, as this second one did not have Servicing Stories Wanted Do you have any good servicing stories that you would like to share in The Serviceman column in SILICON CHIP? If so, why not send those stories in to us? In doesn’t matter what the story is about as long as it’s in some way related to the electronics or electrical industries, to computers or even to car electronics. 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. Celebrating 30 Years February 2018  61 supplies the rotating field of the main alternator and hence alternator output." "The result of all this is that a small DC exciter current indirectly controls the output of the main alternator." Switchmode power supply repair The two GMC 750W generators. The first generator to be repaired, which provided no electrical output from AC or DC, is on the right while the second, which had no fuel taps, is on the left the flap over the 230VAC outlet like the original generator had. So, I wondered whether this 12µF capacitor was the original capacitor that had been fitted to this generator by the manufacturer or if it had been replaced at some stage in the generator's life, before I got it. While I was waiting on the fuel taps and the fuel line, I thought I would use the fuel tank from the original generator to give this second generator a test. After fitting the fuel tank, I tried to start the generator but it would not start. I had already replaced the spark plug and I had spark, so it must be a fuel problem. I removed the spark plug and put a few drops of fuel into the cylinder, then replaced the spark plug and tried to start it again. It fired and ran for around a second, so that meant that fuel was not getting through. I removed the carburettor and took the bottom bowl off it and I noticed some dirt in it. I cleaned this out and removed and cleaned the main jet, which was blocked, before reassembling the carburettor and re-fitting it. Now the engine started and I went through the process of checking it with my multimeter and angle grinder. The generator worked just the same as the original one, so now I had a second working generator. Once the new fuel taps and the fuel line arrived, I fitted them, then reassembled both generators and put them 62 Silicon Chip away ready to be used whenever the need arises. For a small outlay for parts and a bit of work, I now have two working generators, a good result in my book. Editor’s note: brushless alternator designs are attractive because they have a much longer service life due to the lack of brush wear. For those curious about how they work, the following excerpt from Wikipedia should help: "A brushless alternator is composed of two alternators built end-to-end on one shaft. Smaller brushless alternators may look like one unit but the two parts are readily identifiable on the large versions." "The larger of the two sections is the main alternator and the smaller one is the exciter. The exciter has stationary field coils and a rotating armature (power coils)." "The main alternator uses the opposite configuration with a rotating field and stationary armature. A bridge rectifier, called the rotating rectifier assembly, is mounted on the rotor." "Neither brushes nor slip rings are used, which reduces the number of wearing parts. The main alternator has a rotating field as described above and a stationary armature (power generation windings)." "Varying the amount of current through the stationary exciter field coils varies the 3-phase output from the exciter. This output is rectified by a rotating rectifier assembly, mounted on the rotor, and the resultant DC Celebrating 30 Years R. W., of Mt Eliza, Vic, recently had a friend present him with a faulty electronic module from an unknown appliance to fix. They must consider him to be an electronic whiz and he may be, for he soon had it working again. As follows... My friend brought the anonymous module over and told me that it had failed but didn’t give me any more information about it. On inspection, I found it to be a 110-240VAC input switchmode power supply with no protection cage around it. I briefly applied power and discovered that the fuse had blown. So I told my friend to leave it with me and I would see what I can do. I asked him to give me some further information about the board, eg, what piece of equipment it was out of or any circuit diagrams he might have but nothing was forthcoming. As mains switchmode power supplies can be dangerous, I was not looking forward to working on it. Despite using the PCB part number as a search keyword and trawling the internet, I was not able to find a circuit or any information and I did not know who manufactured the equipment it was from, so I could not search for that either. I noticed there were two wire links installed on the PCB and a position for a high-power resistor which was vacant. The links were evidently supposed to be installed for 110VAC operation and omitted for 240VAC. And the missing 27kW resistor was supposed to be installed for 240VAC and omitted for 110VAC. This explained why the fuse had blown; the PCB was configured for 110VAC but had been plugged into 230VAC mains. At least this was a start. I could easily remove two wire links and solder in a high-wattage 27kW resistor once I found one. But what else had blown before the fuse? I decided to remove the board from the chassis and see if I could trace the circuit around the wire links. I found that it uses a full-wave bridge rectifier for 240VAC operation (when the wire siliconchip.com.au links are not installed) but it functions as a half-wave voltage doubler when the links are installed for 110VAC operation. I also noticed that there appeared to be a thermistor wired in series which had burned out. There were also two optoisolators on the board. One seemed to be used to indicate to the control circuit when the AC input was present. I think this signal may be important when power is first applied but I did not trace the circuit further to find out. For 110VAC input, the optoisolator was connected via a 27kW resistor to the incoming AC line. For 240VAC input, there was an extra 27kW resistor in series. When the wire link is installed it shorts out the second 27kW resistor. But for cost-saving reasons, the manufacturer did not install the second resistor when factory configured for 110VAC input. This made me question whether the optoisolator may have been blown when 230VAC was applied. I thought at this point I might as well make the changes required for the unit to operate from 230VAC, plug it in and see if it worked. I didn’t have much to lose; if anything else had failed, it would probably just blow the fuse when powered up. I didn’t have a replacement thermistor but even though a chunk had blown out the side, the resistance across its pins didn’t seem too high at 32W. This was probably higher than a good thermistor but still low enough to allow the power supply to operate with a light load. At least I would know if it still worked. So I made the changes and replaced the fuse. I didn’t have the correct slowblow type of fuse on hand so I decided to use a regular fuse for testing purposes. I hoped that the inrush current at startup would not blow it. Sometimes, you have to try your luck! I put the PCB back into the chassis and sat it on top of a cardboard box to ensure that it was insulated from the top of the workbench. I connected the mains power cord via an earth leakage circuit breaker and switched it on at the power circuit. The fuse did not blow but there was a loud crack as a spark shot out of the side of the thermistor. Without touching the power supply, I carefully connected my Fluke multimeter across each of the DC output connectors. The voltages measured +5.1V DC, +11.95V DC and -11.96V DC. Whoopee! All was OK; I guess one can be lucky sometimes. But I still needed to replace the thermistor and put in a proper slow-blow fuse. On Saturday morning I made a trip to the local electronics store and fitted the new parts that afternoon. The power supply passed a no-load voltage test. Luck was on my side. The fuse had blown before any damage was done other than to the fuse and thermistor. The power Mosfet was clearly OK and the optoisolator had not blown up with only one 27kW resistor in circuit. I made a phone call to my friend to tell him that it was ready to be picked up. We decided to have a BBQ on Sunday and he would collect the power supply at the same time. I did not hear from him whether the power supply worked OK when installed into whatever it came from. I suppose if it had not worked, he would have let me know straight away. Sometimes no news is good news! SC New Rohde & Schwarz oscilloscopes Rohde & Schwarz have recently introduced the two-channel RTC1000 series, a compact, lowcost, high-quality digital storage oscilloscope. It can double as an eight-channel logic analyser, four-channel pattern generator and a protocol analyser for I2C, SPI, UART/RS-232, CAN and LIN; and as a digital voltmeter, component tester, spectrum analyser and counter. With this eightin-one instrument integration, users get more value with a minimal footprint on bench space. For further information contact: Rohde & Schwarz Ph: (02) 8874 5100 Email: sales.australia<at>rohde-schwarz.com Website: www.rohde-schwarz.com/RTC1000 siliconchip.com.au R&S RTC1000 oscilloscopes are available with bandwidths from 50MHz to 300MHz. Bandwidth upgrades are available via software license all the way to 300MHz and can be purchased as needed. The maximum sample rate is 2 GSample/s and memory depth is 2 Msamples. LAN and USB interfaces are standard. Silicon Chip is expecting to obtain an R7A4000series scope/spectrum analyser (another new product) for review in the near future. Celebrating 30 Years February 2018  63