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SERVICEMAN’S LOG The show must go on Dave Thompson The servicing gods must have some kind of influence in our lives; otherwise, how would it be that very similar jobs end up in the workshop at the same time? Kismet? Synchronicity? Pure coincidence? Dumb luck? It happened that I received two large TVs, a turntable and a DVD player to repair, all arriving within days of each other. Now, I have repaired TVs before and found them to be challenging. In fact, I recall helping out my uncle in Melbourne with simple jobs when he ran a thriving TV hire and repair business back in the 1980s. I was on holiday there and loved his workshops, with the mirrors on the back wall so he could watch what the TV was doing as he poked and prodded around in the back of it. I cannot tell a lie, those high-tension leads scared me, and I remember both Dad and him somehow creating huge fat arcs of electricity to the end of screwdrivers just for fun! Not for me, thank you! Of course, those TVs were very different, being huge, heavy things with CRTs and large transformers and discrete circuitry – some even still used valves, which were always fun to work with, in a shocking sort of way. I’ve built dozens of guitar amplifiers, both solid-state and valve-based, but they don’t scare me as much as those old things did. 96 Silicon Chip I have had people ask me if I can look at their old sets – they are into the retro thing but use set-top boxes of some sort to get ‘modern’ signals. I just politely decline; I don’t really know what I’m doing with them, and would likely end up cooking myself on the flyback transformer output. The very model of a modern modular monitor Modern TVs, however, are a different story. Most are now modular, with several circuit boards inside, all performing their separate functions. That makes any repair a lot easier, as long as you can get the boards. The power supply is obvious. It powers any LED backlighting (on older sets) and of course provides power to all the other boards. There is usually a main board that controls video and audio feeds and sends them to the right place (amongst other things like storing settings and personal channel choices). There is also sometimes a T-Con board, short for “timing controller”, which ensures the signals go to the right place at the right time. Some TVs don’t have these T-Con boards as a separate module; it is all incorporated into the main board. So, there is lots going on inside modern TV. Of course, OLED TVs are very similar to LCDs, just with a different type of screen at the front and suitable circuitry to drive it. The rest is pretty much the same. I ended up with two LED (backlit LCD) TVs in the workshop. Anyone who has seen my workshop knows that it is quite small and that it looks like a grenade has gone off inside. So having two rather large TVs in there makes it difficult to move around, which is why I usually don’t take on big jobs (both figuratively and literally). The first TV is one of several models sold by a local big-box store that are priced quite reasonably for their size and specifications. However, there is often a price to pay when buying cheap. This one had no video output, although there was audio, and the remote control seemed to operate all the settings, if the volume was anything to go by. With this type of display, it always pays to have a good look at it from the Australia's electronics magazine siliconchip.com.au Items Covered This Month • The show must go on • Fixing two broken laptops • The danger of high-impedance measurements • Hickok TV-7 valve tester repair • Repairing a Seiko wall clock Dave Thompson runs PC Anytime in Christchurch, NZ. Website: www.pcanytime.co.nz Email: dave<at>pcanytime.co.nz Cartoonist – Louis Decrevel Website: loueee.com side, especially if you’re in poor light. If you can see shadows moving from that angle, it indicates that the panel is doing its thing and the fault is with the backlight. However, in this case, I could see nothing; not good, then. It could be a power supply failure, a screen failure or a mainboard failure. Or even a T-Con board failure. That really narrows it down (not)! It is difficult to get the parts you need to repair these at a component level because these things are all modular now. If something fails, you’re supposed to pull the board, replace it and off you go. However, new boards can be pricey! The evils of a throw-away society I suspect that if these things are returned under warranty, they just give the customer a new one and throw the old one in a skip, which is criminal. The amount of e-waste we generate for such a small country is embarrassing. I know of a printer repair shop that has a literal mountain of old printers, most of which could be repaired with a $10 part (if that). However, because these parts are not available, they just get dumped; the pile is cleared twice a year! Yes, some printer companies have a returns policy where you can take your old one in and they’ll dispose of it. However, that usually means filling containers with this branded waste and sending it to somewhere like Malaysia, Indonesia or (less likely these days) China. The people there either burn it in big piles or smelt it down in crude village furnaces to get any precious metals out of it. The problem is that all the toxins from these basic processes leach into the soil and cause all manner of birth defects and pollution. It certainly makes me think when I am getting rid of an old printer. Anyway, back to the TVs. The other difficulty with finding spares is that parts for these big-box specials are not readily available to the public. The boards have identification numbers on them, so that is where I started, with internet searches. AliExpress had some similar boards listed, but I found more information on forums and in the comments on YouTube videos. It seems these same boards are used in several other brands. Searching for those gave me a lot more information and leads on a spare from eBay. I bought a whole new control board, and after a few weeks, it duly arrived. It certainly looked the same; while the revision number was slightly different, I threw caution to the wind, installed it and pressed the button. This time, after a few flickers, the screen came up with a settings menu. I then went through it with the remote and set it up as best I could. siliconchip.com.au I don’t have an aerial lead out in my workshop, so it was just internal stuff. I connected it up to the internet, and it worked fine, loading the YouTube app and other free ones. I assumed it would load their Netflix and Prime accounts once they re-entered their details and registered the new hardware ID. It was simply then a matter of buttoning it all back up. One job out of the way, then, but it would still very much be in the way in my small workshop until they picked it up! Enter contestant #2 The second TV was slightly smaller, like a rumpus room set that had been demoted from the main lounge for use with the games consoles because the owners bought a new, bigger and shinier one for the lounge. It was older, clunkier and just as dead as the first one. This one was altogether more solid and harder to get apart, with a few hidden – or at least obfuscated – screws. Plus one safety screw, just to make life that little bit more difficult for me. Fortunately, I had a long screwdriver that could reach down the deep plastic tunnel and access the screw. What really rots my togs is that some designer at the company sat in a meeting with the brass and put this idea forward, and it was accepted. They must know it won’t stop people opening the thing up, but they do it anyway, no doubt incurring more expense as yet another step in the assembly process. I eventually managed to get the back off the set, breaking several of the now brittle-from-heat clips that also held the shell together. Once the back was off, which also included undoing the VESA mounted bracket, I could see the three boards inside. This TV is a house-brand device from another big-box store here. This time, there were no identifying part numbers on the boards, and some of the IC’s had scraped off numbers (thanks!). Australia's electronics magazine November 2024  97 I suppose that someone used to repairing these or dealing with them would know where to source parts, but even after I took pictures and tried several search-engine image searches and Chinese site searches, I could not find anything even remotely similar. My usual forums were also of no use; nobody seemed to know who made these things. I’d taken it as far as I could, so I called the client and said sorry that I was unable to do anything with it. Perhaps they could go back through the vendor and hope for a repair there? I heard weeks later that they did just that and were told it was obsolete and non-repairable, which is increasingly the mantra for electronics and appliance vendors these days. The amount of e-waste this terrible policy creates... Don’t get me started on that again! The next job on the list was a turntable, a now-vintage Sansui that back in the day would have cost the owner a pretty penny. This one had been sitting in a container beside the sea for over 20 years, unused, and the other components in the stereo system fared about as well as the turntable did. The speaker cones were rotten through, the metal baskets supporting what was left of them corroded beyond repair. Lord knows what the insides looked like; I envisaged the crossovers looking like something you’d recover from a shipwreck! The amp looked as if it had its own ecosystem growing on it and the tuner looked about as dire as the amp. All this gear was top-of-theline back in the 1980s, but now it looked as if it had been at the bottom of the sea. I flatly told the guy I couldn’t take that kind of restoration on. Not only would i t c o s t a fortune to replace all the rotted parts, there would be no guarantee it 98 Silicon Chip would even be as good as it once was. That’s assuming we managed to find new-old stock parts (he wanted to keep it vintage) and could actually get it working. I just wasn’t prepared to embark upon that sort of quest. He asked if I could look at the turntable at least, and I reluctantly agreed to check it over. He said it worked but made a grinding noise while running. Oh, great. I could just imagine what the bushings and all the motor bearings were going to be like inside, not to mention the state of PCBs or belts (if any) that might be in there. The only thing I could do was to remove the Plexiglas lid and open the thing up to have a look. The platen wouldn’t just lift out, like many I’ve repaired, so it was likely held with a clip underneath. Like most devices of this era, chunky screws held everything together and it’s just a matter of elbow grease to remove them all. Most came out cleanly, but a few were stubborn and needed a little help to let go. Corrosion really does get everywhere. Once the timber base was off (which could actually be easily restored, even though it is only veneered Weet-Bix wood), it was evident this was a project too far, for me at least. The inside reflected the outside. Everything had a powdered layer of corrosion. It would require complete – and I mean complete – disassembly, cleaning and restoration, and reassembly before it would work again. I am not set up for this sort of work, and even if I was, I doubt I would take on such a time-­ consuming task these days. I am sure if this customer set up an alert on the local auction sites he could pick up a good one for a fraction of the price I would have to charge to repair this one. This is where repairs truly make no sense. Unless someone has a deep sentimental attachment to any given appliance, there is a point where we just have to say, that’s it, and pull the pin. Even though this thing was in storage for 20 years, the owner kept hassling me to get it done for some party he was having in a week. He wanted to play records on it, which had been in the same storage container. As if this would ever be a seven-day repair anyway! Oh well, such is the life of a serviceman. Australia's electronics magazine The last job My last related job is a DVD player a client brought in. The whole DVD thing is a bit like watching the slow but sure decline of vinyl and CDs all over again. The problem is, of course, that most of us still siliconchip.com.au have shelves packed with CDs and DVDs. Letting all that go is just as bad as those people who have thousands of records in their collections and can’t let them go either. Keeping the machines that play these media alive is a big job now because, aside from ultra-high-end players or bigbox store cheapies, there’s not a lot in between to choose from. At least, not here in New Zealand. So, the customer brought in a brand-name player to see if I could get it going. It powers up but cannot detect a disc in the player. I’ve seen this before in many a computer CD-ROM or DVD-ROM. It is usually because the laser has simply gotten tired from use and cannot focus on the disc sector that tells the player it is loaded, so it just keeps hunting for one. Many people say their drive doesn’t get much use. However, every time you access This PC or My Computer, or turn a DVD player on, the laser fires to see if there’s a disc in there. So it does some work even when not needed, even if there is no disc present. Over time, the laser just wears out, for lack of a better or more technical term. I have done laser diode swaps in the past in expensive units, but they are an absolute pain to get out of the heatsink/caddy the diode is pressed into. That’s once you drill down to that level to get to it, which in a DVD player is a mission in itself. So I wasn’t about to consider doing anything like that with this one, if that’s indeed what the problem was. The rub is there’s no way of knowing until you swap it out and try it. Once again, I had to do a hard pass on this one. Good quality Blu-ray and DVD home-theatre type players are out there, and often not expensive, so I suggested the customer looked into something like that. The reality is that with high-definition streaming and relatively inexpensive services, physical media is quickly becoming superseded. In our household, I cannot recall the last time I used my DVD player. Perhaps I’ll gift it to this guy to replace his dead one. Editor’s note: many people are going back to physical media due to the fragmentation of streaming services and the ongoing cost of subscribing. Many classic TV shows and movies are no longer available, some even being removed after people had “bought” them! Others have been doctored or censored. So don’t throw away those CDs, DVDs and Blu-rays just yet! For example, see siliconchip.au/ link/ac1k Saving two broken laptops I wanted to send my mate a laptop, so I looked through some I’d had for some time. I decided to repair an Intel Core i5 based laptop we’d previously given to a friend, which had come back broken. The bottom shell was badly damaged, but the rest was in good condition. I was able to salvage an almost identical shell from a similar laptop with lower specifications. The only difference was that this older laptop didn’t have an HDMI port, so I had to cut a hole where the HDMI port was located on the original motherboard. This repair went well and the laptop was shipped off. I also noticed an Acer Aspire laptop among the ‘junk’ that looked like an easy repair. It was missing the keyboard, but otherwise, it was in good order and also had an i5 processor. It wasn’t high-tech any more, but it was good enough for web browsing and emailing. siliconchip.com.au Australia's electronics magazine November 2024  99 I fitted some RAM, plugged in a USB keyboard and a charger and pressed the power button. An initial test confirmed that it worked, so I fitted a 500GB hard drive, but something was wrong. The hard drive went in way too easily. I removed it, looked closer, and found that the SATA port was broken, basically writing off the laptop. How could this laptop be salvaged? I had a thought. I got a 32GB microSD card, put it in an adaptor, and inserted that into the SD card slot. I booted the laptop from a Linux disc and installed Linux on the SD card. I rebooted the computer and it was up and running. The entire installation used only 9GB, so there was plenty of room left to install other programs. That was an easy way to fix and give this broken laptop a new life. Still, I wondered if I could replace the broken SATA hard drive socket so I could fit a 500GB hard drive to install Windows 10 on. I’ve junked a lot of old laptops over time, most of which no longer worked or were really old and in such poor condition that they were unrepairable. However, I’d kept the motherboards, screens and other useful parts for future repairs. I’ve previously been able to salvage USB ports and mouse micro-switches for other repairs, but could I replace a serial ATA socket? I looked through the old motherboards and was surprised at the variety of different SATA sockets. I only managed to find two that looked like they were the same as the one I wanted to replace. After dismantling the laptop, I found that only one was precisely the same, the other one being slightly different, as it sat closer to the motherboard, so it was unsuitable. I considered how to remove the SATA socket from the scrap motherboard. I could either use my heat gun or my 80W soldering iron. I decided to try the heat gun on the socket I didn’t need as a test. While I was able to remove the socket in one piece, it did suffer some slight damage; not bad enough to make it unusable. Still, I decided to use the 80W soldering iron on the socket I needed instead. I successfully removed the socket without damaging it, so it was time to desolder the socket from the good motherboard. I got the socket off successfully with the same iron, but it was quite tricky to remove, as it broke into many small pieces in the process. Now I had to work out how to clean out the tiny holes. I got my desoldering iron, which uses suction to remove the solder. This process was very tedious, but with 100 Silicon Chip perseverance, I got all the holes cleaned out. I fitted the new socket and soldered it in place with my 20W soldering iron. It was time to reassemble the laptop and check if the repair was successful. With the laptop reassembled, I fitted a 500GB hard drive, connected the charger and USB keyboard and pressed the power button. I then pressed the F2 key and waited for the BIOS screen to load. The repair was successful, as the BIOS screen showed that the laptop detected the hard drive. I was unsure if this repair would be successful, with the delicate nature of removing the SATA sockets and fitting the new socket to the motherboard. It seems that I had good luck this time. Now that I knew this repair was successful, it was time to install Windows 10. I used the Windows 7 product key on the back of the laptop, as I had done many times before, but it said I did not have a valid key. What was going on? I looked online and found that Microsoft had just closed this upgrade path. I found a website selling genuine Windows keys at a reasonable price, so I paid for one and it worked. Now the laptop was all good again, so I ordered a new keyboard and fitted it. The repair was complete, and the laptop was saved. B. P., Dundathu, Qld. An impediment to learning Recently, I was behind a car in traffic and noticed that every time the driver applied the brake, one tail light went out. I have some experience with this simple fault, but it can cause frustration for those who happen upon it for the first time. Back in the 1960s, I did my time as an electrical apprentice with what was then the South Australian Railways, mainly at the Islington Railway Workshop. During my training, I was exposed to repairing, maintaining or installing various equipment ranging from low voltage DC (automotive electrics), higher voltage DC (32V, 64V and 110V on rail cars and locomotives), batteries, 240/415V AC industrial machinery, power tools and domestic appliances as well as switchboards for equipment control circuits, lighting and air conditioning within carriages. It was during my stint looking after the battery shop and vehicle electrics that I encountered the brake/tail light fault and learned an enduring lesson. Several years later, I was working in an Army workshop in Hobart as the resident electrician when one of the tradesmen from the vehicle service station begged my help with a Land Rover that had a tail light problem. On arriving at the service station, I was confronted with a vehicle with all the covers off and switches and wiring exposed. The mechanics had spent the best part of five hours trying to find the source of the fault and were not amused when I showed them a high-resistance chassis ground connection on the offending tail light. My input took about three minutes, leaving them with several hours of work putting everything else back together. Back in my apprentice days, the standard multimeter we used was the AVO 8, a reliable device but rather hard to carry and use compared to modern meters. The AVO was a relatively low-impedance meter compared to today’s devices. Late one afternoon, a carriage traverser stopped working, which was needed in service the next morning. Australia's electronics magazine siliconchip.com.au A carriage traverser is a section of rail on a platform that can move sideways to transfer rolling stock from one track to another parallel one. The traverser had a threephase motor to drive the axles to effect the track changes, but there was no power to it. It came via an underground mains feed to a pit, then up a pole via contactor to overhead catenary cables to pickups on the traverser. Being the youngest, I was sent into the pit to test for power to the catenary feed and had the AVO 8 in hand. One of the engineers who had come to see what was happening had a brand-new high-impedance “Sanwa” meter that had arrived only a day or so previous, and passed that meter to me to use instead of the AVO. Using the Sanwa to measure between phases, I got readings of 360V AC and 730V AC instead of the expected 415V AC. That had us all scratching our heads. Swapping back to the AVO, the readings were all zero; another puzzle. Looking upwards, I noticed that the high-tension overhead power line ran parallel to the underground feed. I then realised that the high-impedance meter was reading an induced voltage from the overhead supply. A failed supply fuse to the three-phase contactor was the cause of the fault, and that was easily fixed. Twenty years later, I was working as a supervisor in an electrical workshop at Puckapunyal when a trainee attempting to diagnose a fault on a water cooler was confounded when the wires to a small terminal strip, including switch wires, were all showing 240V to Neutral. He was using the standard issue Fluke multimeter. Sensing déjà vu, I took the Fluke away, handed him the Army “Aust Mk II” multimeter, a low impedance meter, and asked him to repeat the measurements. It was his turn to learn about induced voltages and high-impedance measuring devices. Some lessons learned early never fade. G. D., Mill Park, Vic. Hickok TV-7 valve tester repair My TV-7 D/U valve tester failed the other day. The meter was stuck and moving erratically and the “line set” could not be completed at switch-on. I immediately thought that the meter had failed (which it had), but the mode of failure was what surprised me. I have had this tester for about 12 years. I bought it on eBay when I was living in Tokyo; it’s ex-USAF and has a colourful history. It is in remarkable condition (my alltime favourite). At the time (2012), our dollar was close to parity with the USD, so this tester ended up costing me about $450. I bought about 20 pieces of equipment and had them shipped straight to Australia before the “Harvey Norman” tax on imports; times were good! Anyway, I pulled the meter and removed the Perspex lens, and then suddenly the meter worked perfectly again. I figured I’d put it back in and try it out. I got the same problem; in fact, just wiping my finger across the front caused the meter to move and get stuck in weird positions. These meters were made by Phaostron. They are great because there is a knurled knob inside that you can adjust to change the full-scale deflection (FSD). It works as a magnetic shunt, allowing more or less magnetic intensity through the moving coil (even HP didn’t have this). However, apart from this chestnut, the meters are jewel-­ pivot, not taut-band like HP. Still, I have never had a single siliconchip.com.au Australia's electronics magazine November 2024  101 one get stuck, and I have played with hundreds (another story)... The problem was that the plastic lens on the front was retaining a static charge, causing the needle to misbehave. Most Phaostron meters had an anti-static coating on the inside of the Perspex to prevent that, but perhaps the coating has broken down over the last half-century. I was very surprised as this meter never had any static issues like you expect to see in cheaper plastic meters. Again, this is where the big old HP meters triumph, as they were constructed with anti-static Bakelite and glass lenses. The resolution was to pull the guts out of the meter and transplant them into another Phaostron housing that was made much later (circa 1980s). This had a glass lens; obviously they realised the problem with plastic, or ruggedness was no longer a USAF requirement. In any case, the meter now works perfectly again. Happy days! D. V., Hervey Bay, Qld. Seiko wall clock repair I am sending this in case someone has the same trouble. I probably would not have bothered to fix it because I have too many clocks around the place as it is, but this one has been with me for around 50 years and has a lot of sentimental value. The clock used to keep good time, but over the last couple of years, it was out by up to 20 minutes a month. Try as I may to adjust it, I always failed to get any sort of accuracy. At the beginning of this year, it kept stopping but always started OK. I overhauled the mechanism, which seemed to fix it, but only for a while. Eventually, it stopped and would not start, so I opened it up again and tested some of the components. All tested good except for what I would call the driver coil. I could never get the same resistance reading twice. It varied from 3kW to 3.5kW. The driver transistor was a germanium PNP type. It was easy to remove, so I took it out and tested it, and it was good. To see if a silicon transistor would work, I replaced it with one of those with the closest characteristics. I set the clock up on the bench and it started, but it only ran for a couple of days before stopping, and it would not start again. That meant the driver coil was faulty; I suspect it had intermittently shorted turns. I removed the tape from the coil and found that all the connections were good. I then put the coil on a spindle and unwound all the wire; there were no breaks. I tried to rewind it with some wire off another coil but did not have any success. If the bobbin hadn’t had mounting feet on it, I may have got away with it. But my 77-year-old eyes were watering just trying to see the 0.076mm diameter wire, and when it broke, I gave up. I looked in my relay box but could not find a coil with a big enough hole up the centre for the pendulum rod, so I left it on the bench in case an idea came to mind. I later had a thought that a washing machine water solenoid coil might do the job. I had some in a box and found a few that measured 3.6kW, so I removed the coil. The centre hole was smaller than the original in the clock but large enough to fit over the pendulum rod. By drilling a 29mm hole in a piece of timber 20mm thick, cutting it in half and drilling some holes for mounting bolts, I could set it up to see if the clock worked. It did not. The pendulum in this clock actually drives the gears via a ratchet and pawl system, and the coil did not have enough pull. I shorted out the 1kW series resistor, and although there was an improvement, the clock still did not run. I had been wanting to run the clock from a rechargeable battery in a holder at the bottom of the case to save me having to take the clock down from the wall every time it needed a battery change, so I tried two Eneloop NiMH batteries in series, taking the voltage from 1.5V to 2.4V. The modified clock runs fine with this arrangement, even with the 1kW resistor back in the circuit, and has been doing so for four months. Not only that, but once I got it adjusted, it kept perfect time. I slotted the holes for the coil mount and made a brass plate with tapped holes for the screws. Now I can adjust the position of the coil to suit where the pendulum rod ends up, after changing its length to make it keep the correct time, without having to take it down from the wall. I painted the coil and wood clamp black so they were not visible with the glass door closed. I left the original transistor and coil former in the bottom of the case. The curved rod that enters the coils has a magnet on both ends. It induces a current in the coil large enough to switch on the transistor at the right time. SC R. G., Cooloola Cove, Qld. The internals of the Seiko clock, showing the curved rod and coils (left), and the modified circuit diagram (right). 102 Silicon Chip Australia's electronics magazine siliconchip.com.au