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SERVICEMAN’S LOG All washed up Dave Thompson It’s always difficult when an appliance in the household breaks down because we are obliged to at least take a look, even if we have no idea what we are doing. It’s the Serviceman’s Curse, and I’m guessing we all suffer from it to some extent. So of course, when our washing machine chucked a wobbly, I felt that I had to troubleshoot it, to see if I could do anything before calling in an actual (and likely really expensive) repair person to have a proper look at it. I’m sure you are all aware that I am not an expert on washing machines. I mean, I know basically how they work: water, soap of some type, agitation, rinse, repeat and then they shake themselves all over the floor while they turn into a huge salad spinner. The rest is timers, valves, sensors, solenoids and motors; how many of each usually depends on the complexity of the individual machine. Ye olde clothes washer I’ll always have an image of my mother standing in our laundry in the 1960s, working on what was then a pretty modern machine. I can’t recall the brand exactly, but it was likely a Fisher & Paykel wringer type, popular at the time. It was basically a big round basin with a motor underneath and a spindle in the middle, or, and I’m going out on a limb here, an ‘agitator’. The agitator went backwards and forwards and shredded the clothes and sheets, or whatever was in it. A big lever on the side engaged the thrasher and meant you could load it and get everything ready before kicking it into gear. Mounted on top was a fearsome ‘wringer’: two rollers that were driven by the motor and engaged by that lever on the side, which disengaged the agitator. Those rollers could be tensioned with a large, cast-iron knob at the top. A shaped drain at the bottom of the rollers guided any water wrung from the washing back into the main tub. The whole wringer assembly also had a safety mechanism built into it so that when dumb kids like my brother put his hand in there, it would pop open. That would release the downward pressure on the rollers, allowing him to pull his hand or arm back out. As a system, it was a simple and actually brilliant design. The machine worked well, aside from ruining just about anything washed in it finer than denim. Still, this pressure-­ sensitive wringer safety system used to trip all the time with mum just putting things like sheets or heavier wet fabrics through it. So in the end, she cranked that thing down so tight that it wouldn’t trip at all. The obvious concern is that your arm would come out like a pancake if you were silly enough to get it caught in there. And going by anecdotal evidence at the time, plenty of people did! I was always too afraid to get anywhere near it, but mum was braver and fed the clothes and linens through it, with her fingers ending up dangerously close to the rollers! I suppose she knew what she was doing, having worked the thing every other day for a long time. Of course, things have moved on a lot from those days. Aside from the Hoover-matic style twin-tub horrors of the 1970s, most subsequent machines have been more efficient and more reliable. Indeed, some appear to have lasted forever, if the washers I came across in flats I rented were anything to go by! Not to be sexist, but housewives of the day wouldn’t put up with something that didn’t work properly or would make their lives harder, preferring to utilise tools that made their lot easier. Front vs top loaders We now use a front-loading style of washing machine in our household. These use a lot less water than top loaders and are generally more efficient with power and soap use. Most European countries use front loaders, and as my wife is from Europe, we went with what she knows. Happy wife, happy life! The reason for this in Europe is water usage (households there pay for the water they use, something most cities in New Zealand do not do). Moreover, there’s the simple and practical fact that many people living in apartments have the washing machine in the kitchen, and it sits under a counter or bench like a dishwasher, so top loading is not typically an option there. Our machine is from a well-known Korean manufacturer of home electronics, smartphones and whiteware. It 88 Silicon Chip Australia's electronics magazine siliconchip.com.au is the second model we’ve had from that maker in the past 25 years, so I’d call that reliable (although I’d like to think mum’s first F&P is likely still going somewhere!). The first machine simply wore out, and as is typical, was too expensive to replace all the bits that needed replacing – at least, those that were still available. So, we invested in a flash new model with a few other bells and whistles on it, not that it turns out we use any of them anyway (marketing works!). We basically use the same program for everything we do. I didn’t know we had a pool This has been a very good machine too. Except one morning, I got up to go and hang out the washing we’d done the night before, and there was a swimming pool in the laundry. Great! Just what I needed. I also could not open the door of the washer, an electronically applied safety feature designed to prevent, well, swimming pools on the laundry floor. Usually, the last thing you want with a front loader half full of water is to open the door! This is one of the few advantages of a top loader, in my opinion; you can stop it mid-cycle, open the top and do what you need to do without a disaster in the laundry. My first thought for the water egress is that the big, circular door seal had gone. These seals work like an oil seal in the gearbox of a car (or the diff, you choose). The pressure and weight of any water behind it ensures a decent seal on the surface, in this case the glass front window, which of course is opened and closed all the time to load and unload the washer. That opening and closing can wear it out. Any grit or anything else that gets through the filters can damage the fragile seal as well. Usually, the door will not open until the pump has evacuated all the water, and only then does the door lock deactivate. In the old days this was a simple mechanical lock, but now, of course, is a much more complex electronic type of arrangement utilising sensors and solenoids and likely smoke, mirrors and ball bearings, knowing modern designers. Maintaining that seal on the door glass is likely where millions of research dollars were spent (and probably more than a few buckets and mops!). They do seem to have gotten the hang of it though, as our machines have never leaked from there. siliconchip.com.au But leak this one has. And cleaning up water spills is time-consuming; there’s also the potential damage to all the cabinetry in the laundry to worry about. The Weet-Bix wood this stuff is made from is like a sponge and will soak up any moisture it comes into contact with, despite the rock-hard melamine laminate on the outside. Once the lake was dealt with, I turned my attention to the machine itself. The water didn’t seem to have come from the door – there were no tell-tale watermarks. In fact, the whole cabinet appeared to be stain-free. My amateur washing-­ machine repair brain thought the obvious: a clogged filter? Fortunately, this is something the owner can usually fix without too much difficulty, with panels provided for access to the filter(s). The problem here was that the panel was very tightly fitted, and I had to prudently use a spudger type tool to pop it clear. Once off, I could clearly see the filter assembly and it was dry all around it, so I guessed the water didn’t come from there. I still opened it, took the filter out and cleaned it. We have three cats (I know) and though short-haired, they still drop a large amount of hair. Relentless vacuuming and sweeping typically keeps it at bay, but clothes love gathering hair, and that is what filters are for in washing machines (well, that and the tissues or bits of paper you might have forgotten in pockets). There was surprisingly little detritus in the filter, but I cleaned it out anyway and replaced it. The cover popped back in with a satisfying click, and I could see there was no chance of it falling off even with the most unbalanced of washing loads. So, not the filter then. This was fast becoming something beyond my scope of abilities. Time to bite the projectile and get in someone who actually knows what they are doing. Getting some help The next challenge was finding a repair provider who knows these machines. Several I called told me they weren’t familiar with them, which is madness because the brand is one of the most famous in the world. I guess the manufacturer might have a watertight (har!) service policy with repair agents, a la Apple and their guys, but I got the impression that these people just hadn’t worked on one of these types before; Australia's electronics magazine December 2024  89 Items Covered This Month • Treading (un)familiar water • Faults take many shapes and sounds • A rattling fan bearing • Repairing an automatic HDMI switch for PVRs 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 not an ideal situation. I finally did get hold of one outfit that was an official repair agent for these machines, and he said he had a good idea as to what might have caused this problem. I wasn’t going to be presumptuous and ask him what that might be – even I respect a serviceman’s right to make a living! The fact is, I was happy to pay for someone who knew what they were doing to come and fix it. It seemed to me the water was coming from inside somewhere, and I wasn’t about to break open the sides and covers just to find out I couldn’t fix it anyway. So, I made a time for this guy – which exposes another annoying aspect of this type of repair. Afternoon or morning? I mean, when I had vans on the road I would nail a time down on the phone long before we got there, and unless something like a natural disaster happened, we’d be there at that time. These people seem to operate in half-days. You’d think that after years of repairing whiteware, they’d have a better idea of time management. This would mean I’d have to sit around waiting for the guy to turn up any time between 1pm and 5:30pm. Being self-employed, taking time off work is not a huge deal, but imagine if I had to come back from my job and take time off just to accommodate a repair guy? That doesn’t seem right to me. These days, they can always text when they are on their way, but it is still disruptive and generally why I dislike relying on third parties. Still, he arrived with his toolkit and started with the usual troubleshooting procedures. He also asked what detergents and additives we used. I showed him the liquid soap and softener we used in the machine. We’ve used them since day one, so I couldn’t really see the relevance as far as the soap goes, but we’ll come to that later. I was more concerned about a sensor that wasn’t detecting water levels or a valve that wasn’t closing properly, something along those lines anyway. Well, this guy seemed to know what he was doing, so I left him to it. I know how annoying a hovering customer can be! He pulled the machine out (easy enough to do on the two wheels in the front) and whipped the case off with practised ease. I was keeping a little look-out, but it all looked alien to me inside it. A simple resolution After having a good look around, he dismantled the soap dispenser and discovered it was completely gooped up. I know this is a technical term, so bear with me. It seems that some detergents and washing powders don’t break down so easily with the water in our pipes and the residue builds up over time, causing problems. The guy showed me the soap tray. It’s just a plastic thing with many holes in it, and usually the soap and water mixture drains through it. This one, however, was coated in a thick slime of residue. The holes were blocked and, of course, nothing could get through them. The water fills up as part of the wash cycle and should drain through this assembly. However, if the holes are blocked, it just fills up and pours over the top, then down through the appliance until it floods the floor. Because this fills up with water several times a cycle, and it has nowhere to go, it just pours over the top of the dispenser and ends up on the floor of the laundry. So that at least explains why we had a lake in the laundry. Then what is the answer to this problem? Different detergents? Removing and flushing out the dispenser regularly? You would think that the manufacturer would be well aware of these problems, but there are no alerts or advisories, no cautionary tales on their social media. I guess it all comes down to the different water in certain countries, whether it is ‘hard’ or ‘soft’ and how it reacts with the various products and soaps that are available. At the end of the day, it was a simple fix: clean out the gunk. However, when I was looking at the machine, I was thinking all manner of potential problems; the Serviceman’s Curse was at play again. Overthinking it is typical for me. The thing is I don’t really know how these things work, and blocked drain holes in the water/soap dispenser is not really a logical thing for me to think of if the machine starts leaking. The repair guy knew (I think) pretty much right away what was likely to be wrong. He basically told us to avoid a certain brand of fabric softener that is known (in this machine in this country at least) to cause problems. If it doesn’t break down completely in water, it can’t be all that good for clothes anyway, which is something else he hinted at. I guess we won’t be using it any longer. A good enough ‘fix’ then, and well worth getting a professional serviceman in – I would have never known of this problem unless he’d told me. Faults have many causes I recently repaired a studio monitor speaker. These are fairly common items for home studios and often have a 6-inch (15cm) or 8-inch (20cm) woofer and a dome tweeter. The more expensive units are bi-amped, meaning they have separate amplifiers for the two drivers. Often, the amplifiers 90 Silicon Chip Australia's electronics magazine siliconchip.com.au are built around power amplifier ICs to simplify construction, as was the case with this unit. The fault was no sound, but the power indicator was lit. Given that it has separate amplifiers for the woofer and tweeter, it seemed unlikely the fault was there. However, they are usually connected to a common mute circuit, so the fault could be there, or in the preamp or power supply. The first thing I noticed on opening it up was glue covering a lot of the circuit board. This is put there by the manufacturer to secure the large capacitors to the board. I checked the +15V and -15V supplies to the preamp and discovered the +15V rail was slightly negative. So there was a problem with the series regulator feeding this rail. A quick check showed the resistor feeding the base of the regulator transistor was open-circuit. Pulling it from the board revealed why. The underside of the resistor was covered in glue, which limited its ability to dissipate any heat. The resistor was a 0.5W type, and a quick calculation showed it was dissipating about 0.3W. I replaced it with a 1W type and stood it up off the board a little to help get some air around it. I also replaced the resistor doing the same function in the -15V regulator, the underside of which was also covered in glue. I removed as much of the glue from the board as I could while doing so. In other units, I have found the same glue, which starts life as a honey colour, has turned dark brown or black with heat and becomes conductive and corrosive. In some cases, the glue gets into the through-hole vias on double-sided boards and corrodes the connection. Such faults are not easy to find. In this case, just two replacement resistors restored normal operation. My next repair relates to the Styloclone project in the August 2024 issue (siliconchip.au/Article/16415). I was aware of the original Stylophone as I owned one; it was a horrible beast. The sound it produced was basically square waves and the noise becomes grating after a short while. I note the Styloclone has a capacitor filter to help with this. The unit pictured here is called “Wasp” and was made in the late 1970s by an English company called Electronic Dream Plant (EDP). I have been servicing music electronics for more than 50 years, and I have never seen one of these before. This unit does not use a stylus; instead, the keys react to touch. I thought it was somewhat of a toy at first, but once I got it going, I found it to be a capable synthesizer with nice tone. The customer helped me find the first fault as he said there was a wire off inside and he was right. The filter section has a rotary switch to select between HPF, LPF or Band Pass Filter and this switch had worked loose, allowing it to rotate and break wires off. Only one wire was broken, which should have been connected to the wiper of the switch. With the wire repaired and all the switches and pots tightened to the board, we now had sound. The controls were all noisy; a small squirt of switch cleaner in each fixed that. All was looking good until I tested all the functions and found the Filter Envelope Generator was not working. To my surprise, an internet search located a service manual. The circuit diagram was hand-drawn, difficult to read and rather complicated. Further on in the manual, parts of the diagram had been redrawn nicely, including the part I was interested in. siliconchip.com.au The studio monitor PCB with glue on the capacitors. An internal shot of the “Wasp”. Australia's electronics magazine December 2024  91 The Envelope Generator uses three ICs to do its job: a 4013 flip-flop, a 4016 quad CMOS switch and an LM3900 Norton (current feedback) op amp. They are not commonly used anymore. I was aware of them but had to look up a data sheet to refresh my memory how they work. A few measurements allowed me to determine the LM3900 was the culprit. I remember having some in stock decades ago but figured they are probably obsolete. A deep dive into several parts boxes uncovered a bag with one left in it. This solved the problem and this instrument was ready to go. The customer also had the matching sequencer for this, called The Spider, which was dead. I found a faulty 5V regulator, but it still would not work properly after replacing it. I had to give up on that, as it appeared the RAM was faulty and was also obsolete. P. M., Christchurch, New Zealand. Fanning out troubles I have had a Vulcan Tangi fan heater since 1974. I bought it when I joined the RAAF as some of the base accommodation at the time was poorly heated. It has served me well over the years but has not seen continuous use. The fan motors in these are small shaded-pole induction types with bronze bearings, which tend to wear, causing the fan to rattle. I purchased a spare motor in the 70s, replacing the original in 1989. That motor developed the same rattle, but by 2020, spares had become impossible to find, so I just put up with the noise until I could find a replacement. As luck would have it, I was perusing some exhaust fans on display at my local Mitre 10, and one looked like it had an identical motor. It was worth a punt for the bargain price of $16. On removing the old motor, it was apparent that this was an exact replacement, except that the drive shaft was 2.5cm longer and the diameter was 2mm larger. Neither was a problem, as the fan connects to the motor by a grommeted hole that could accommodate the diameter. The extra length would be hidden within the tangential fan. This worked well, with the bearing rattle gone, but an occasional different rattle remained, and I could not determine the source. Then, one day recently, there was a bang. The fan stopped immediately and a burning smell emanated until the over-temperature cut-out operated. The selector switch has a couple of RFI suppression capacitors on it, and I suspected one had failed, but that didn’t explain the stopped fan. Dismantling the heater showed that a fan blade had separated and had stopped the fan while the capacitors were intact. I checked the internet for spares but none were available. There was a fan for a Westinghouse oven that looked identical, but the supplier did not return my requests for dimensions, and at $95, it would not be worthwhile. Could it be repaired? The fan was made of aluminium and was attached to the steel drive disc by mechanical straking. The broken blade had separated at the joint. It was a weak point and impossible to weld, so I tried some JB Weld epoxy resin around the blade. To keep the fan in balance, I applied some around the other blades at that end. A coat of sprayed black paint and the fan was more rigid than when new. After reassembling the heater, test runs showed no signs of rattling at all. This heater is nearly 50 years old and undoubtedly has The “Wasp” styloclone made by Electronic Dream Plant (EDP), this time with its case on. 92 Silicon Chip Australia's electronics magazine siliconchip.com.au exceeded the life that the designers at Vulcan intended. It is a testament to the quality of goods we made here in Australia at the time. R. W., Hadspen, Tasmania Automatic HDMI switch repair We have two personal video recorders (PVRs) in our lounge room. Each can record two channels at the same time. The main one is used for most of the recording and playback, while the second one is used for the odd occasion when there might be three programs on at the same time that we want to record. Several years ago, when I set everything up, I bought an automatic HDMI switch on eBay. It automatically switches the video and sound from the active HDMI cable input to the TV. So, when one PVR is on, the signal is routed to the TV automatically. This works well; the only time the switch needs attention is if the second PVR happens to turn on while using the first or vice-versa. In that case, it’s necessary to push the button on the switch to change back to the other PVR. This system worked well for several years until the automatic HDMI switch stopped working. At first, I was not sure why I was not getting a signal to the TV, but when I looked at the HDMI switch, I could see that the LED was not illuminated. I replaced it with a remote-controlled HDMI switch I’d picked up recently, but it was unreliable. So I decided to have a look at the automatic HDMI switch to see what was inside it. It comes apart easily by removing four screws on the back and lifting it apart. Then the circuit board just comes out, as it’s held in by both case halves. I was unsure if the main IC had failed, so I decided to test the two 100µF 10V electrolytic capacitors and sure enough, one had an ESR of 9.2W. I looked in my salvaged capacitors, but I could not find one that was tall and thin; I found a shorter, larger diameter one that I fitted to the board (the one in the lower-right corner of the board). Sure enough, this put the HDMI switch back into working order, so I could ditch the unreliable remote-controlled one. SC B. P., Dundathu, Qld. 500 POWER WATTS AMPLIFIER Produce big, clear sound with low noise and distortion with our massive 500W Amplifier. It's robust, includes load line protection and if you use two of them together, you can deliver 1000W into a single 8Ω loudspeaker! PARTS FOR BUILDING: 500W Amplifier PCB Set of hard-to-get parts SC6367 SC6019 $25 + postage $180 + postage SC6019 is a set of the critical parts needed to build one 500W Amplifier module (PCB sold separately; SC6367); see the parts list on the website for what’s included. Most other parts can be purchased from Jaycar or Altronics. Read the articles in the April – May 2022 issues of Silicon Chip: siliconchip.com.au/Series/380 siliconchip.com.au Australia's electronics magazine December 2024  93