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SERVICEMAN’S LOG Music to my ears Dave Thompson It may seem obvious to many regular readers that I am ‘into’ music. Or perhaps it isn’t that obvious, but rest assured, I am into it! So, not surprisingly, a lot of the gear I’ve fixed over the years has been related to musical instruments and hifi equipment. I both listen to and play music, and I have done so since I was eight years old, when I was taught piano by an elderly Hungarian Jewish man who lived just around the corner. He was a very good player and a very good teacher. He had some stories to tell about the war years – which were likely heavily sanitised for my tender young ears! Sadly, he passed away a few years after I started, so I changed teachers. That killed my piano-playing career. What it did teach me is that having the right teacher is crucial. While I still play instruments today, I don’t play any of them anywhere near as much as I used to, or should. As for listening to music, I have my favourites, of course, but am not averse to listening to anything new coming along. I know what I like (usually within seconds of starting), so these days I stick with what I know, or I check out recommendations from others I know who have similar tastes (that includes some of the folks producing this magazine). All that said, I am definitely not one of those guys with a library-sized collection of vinyl, playing them on an audiophile-­ level home audio system. You know 80 Silicon Chip the ones, with those thousand-dollar-per-metre speaker cables made from unobtanium and Mars dust. My earliest dabbling in electronics – with a lot of help and encouragement from my dad – was with simple oscillators, crystal radio sets and very basic amplifiers. It fast became a keen interest, and the more I got into it, the more I saw music-related potential. I don’t think I was alone with these interests either, if the number of music-related projects in the magazines of the day was anything to go by. I took it as a sure sign that others were as keen as I was, and I was proven right. There was even a relatively short-lived magazine out of England that featured just that: electronics, current music technology and really cool projects for musicians. I have every copy stored away somewhere, but there weren’t that many with that first-generation theme before it morphed into something that wasn’t of much interest to me. Publishing is tough in any field, time period, or country! It seemed every month, one magazine or another would have an interesting music project. I must have built many dozens of them (mostly on prototype boards); some useful, some just gimmicks. Still, it was all educational and much grist for my mill back then. Making projects kept me busy while I should have been practising, but I had a lot to learn, and so I was very eager to do both as much as I could. I saved all my newspaper delivery money (then my parttime after-school job earnings) to buy these magazines and then the relevant components for projects. I still have large stacks of the mags in storage (and components!). Sadly, the magazines will likely end up in the recycling bin if I can’t give them away. I’ve seen many people trying to pass on complete collections of magazines and libraries worth of books over the years, but the modern age, with much of it digitised retroactively anyway, what’s the point in keeping vast collections, other than just that – collecting them? It seems such a waste, but it’s just reality. Years ago, as a wee tacker, I made everything from tone boosters, fuzz boxes, wah pedals and metronomes until, after a while, I was making increasingly complex projects such as my own stereo amps, preamps, full-blown PA amps, speaker cabinets, mixing consoles, guitar/bass/ keyboard amps, microphones, wireless systems and guitars themselves. I wanted to be able to record music at home, on a computer, and that’s where this music rabbit-hole led me. Australia's electronics magazine siliconchip.com.au Back in those days, the go-to home recording device, if you could afford one, was something like a Tascam or a Fostex four-track, which recorded onto standard cassette tapes. They were pretty good for their day, but as we know, cassette tapes aren’t the best for audio quality, especially if they were used to ‘dub’ or ‘bounce’ many tracks down into one track a few times. The step up from there was into a reel-to-reel four-track or, if you owned a corporation, an eight-track reel-to-reel that used half-inch tape. They had much better audio quality. Fun fact: The Beatles’ album Sgt. Pepper’s Lonely Hearts Club Band was recorded on just two Studer J37 four-track recorders (using one-inch tape), synched together electronically by audio engineers, at what later became Abbey Road Studios. This shows what could be accomplished in 1966 with some very good gear and much lateral creative thinking, producing and mixing. Those cassette-based four-track recording machines were very much a 1980s child and, as they were relatively affordable, they launched the imaginations of many and the possibility of a viable home recording studio. All was well then, but recording at home is not just a matter of grabbing some digital audio workstation (DAW) software from the interwebs, plugging in your microphone, keyboard or guitar to your computer and laying down a new number-one hit single. While you’d think that the computer already has analog inputs to allow instrument/microphone/line connections, the CPU has to work hard to crunch that signal into a digital form so the computer can process, store and manipulate it. You might be surprised to know that most built-in ‘sound cards’ - while most are built onto the motherboard now, people still call them sound cards – are pretty much useless for doing any studio-level sound processing. Yes, they can record speech and basic mic audio, but there are inherent problems. For example, if you want to monitor recorded audio through headphones while multitracking, there is a delay between input and output signals as the computer struggles to keep up. This is called latency and makes onboard sound unsuitable for multitrack recording, where there must be minimal latency between in and output signals. So, an external sound interface is usually the way to go. These typically connect via USB or Thunderbolt, operating similarly to an accelerated graphics card in that the interface handles all the audio heavy-lifting for the computer. To do this, a special driver is needed, called an ASIO driver (Audio Stream Input/Output). This was developed by the Steinberg company in the late 1990s specifically to Items Covered This Month • Musical instruments and USB ASIO card repair • Repairing a Simpson Contessa washing machine • A powerless Li-ion charger • Small replacements for a Dyson fan • Fixing a Samsung TV 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 siliconchip.com.au reduce latency and allow the processing of multiple concurrent audio streams. Usually, these drivers are supplied with the interface, or available as a download or, at a push, a generic freeware ASIO driver. Interfaces cost anywhere from under a hundred bucks to several thousand, depending on what you want. My Line 6 Toneport UX2 is almost vintage now, yet still cost me 500 bucks second-hand in 2003. It still works perfectly for my needs – or it did until recently. It is connected permanently to my PC and acts as a normal sound card when just listening to music or watching YouTube, but it’s when all the audio inputs are utilised with a DAW that we really see and hear the difference. The problem now is its age. All the pots are scratchy, some of the sockets are intermittent, and it is just not right. So I decided that it was finally time to do something about it. The beauty of this era of music gear is that it really is ‘analog’ and it was designed with repair in mind. Typically, clamshell plastic or metal cases were screwed together with normal screws, meaning easy disassembly. All the sockets utilised in most pedals and music gear are standard components, most of which are still available. However, this unit is interesting in a few different ways. Disassembling it was odd from the start; after turning it over multiple times (no doubt with a puzzled look on my face), I simply couldn’t see how it was held together. There are no obvious screws underneath. I even popped one of the four glued-on rubber feet off to check for hidden screws (as is typical of many laptops) but I found none. I thought maybe that the four rotary controls (two independent mic input gains, headphones volume and output level) located on the top half of the case might actually be holding it all together. However, when I popped the knobs off, I saw that Line6 had simply extended the pot shafts up through the top of the case, so they actually didn’t hold down anything at all. Interesting... It turns out there are no screws and no clips; just a friction fit that holds the top half of the case to the bottom, although the front and back panels also play a vital part. Australia's electronics magazine June 2026  81 It’s always a little scary when applying pressure to something that might be clipped or screwed (oh for a small X-ray machine!) but it eventually let go and eased apart with gently increasing pressure. This left the top of the PCB exposed, with the front and back panels still engaged in a slot that runs around the edges of both halves of the case. It’s a purposely tight fit and, when the case is assembled, it all holds itself together. Given that this is designed to sit on a desk and not go on the road, this is an elegant (and likely cheaper) way of holding it all together. Both the front and back panels are an odd but very cleverly implemented two-layer lamination. These consist of the screen-printed, outward-facing coloured fascia, and behind it, a very thin metal laminate, which is no doubt added for shielding and grounding. Between them, they fill the slot around the case edge perfectly, with a pleasing, ever-so-snug interference fit. It has obviously been carefully thought out by the designers and well-implemented by the manufacturers (what we pay the bigger dollars for, I suppose). The back panel is held onto the PCB by a raft of 6.35mm 82 Silicon Chip (¼-inch) jack sockets and a sole RCA socket. These are the line in, footswitch, S/PDIF and analog output sockets. I never use those anyway, except for the USB connector (which utilises the older, but still widely used USB-B type connector), so I left that panel alone; there was no point in taking it off. The multi-layer PCB itself is packed with assorted sockets, pots, a couple of backlit, olde-worlde analog VU meters and what looked to be about a million SMD components distributed in between the bigger parts. I decided to remove the front panel, mainly for easier access to some of the sockets and switches that live right behind it. The PCB was held to the panel by the barrel nuts and black plastic washers of three 6.35mm jack sockets and four (surprisingly long) machine screws holding on to two Canon XLR sockets. Both socket types are the universal standard for plugging instruments and microphones into audio gear. There are two guitar inputs (one normal and one ‘padded’ for hotter inputs) and a headphone jack output. Removing the barrel nuts on the jacks exposes some interesting, thick, multi-pinned plastic locating washers that hold the jack sockets fast into the front panel without any risk of Australia's electronics magazine siliconchip.com.au the socket turning (as often happens with chassis mounted versions of these same sockets), as shown in the photo. More importantly, this locking system prevents the transference of any cable pressure or tension directly onto the fragile PCB. One common mistake I’ve made myself many times before is to forget I’m plugged into something and walk away, blissfully unaware that when the length of the cable runs out, some huge stresses are going to be inflicted on those poor sockets at either end. I’ve done this with power tools, laptops, mobile phones, headphones and guitars. We’ve likely all done it! The two XLR connectors are solely for microphone inputs and have two screws per socket. The only other control on the front panel is a push-on/push-off phantom power switch for sending 48V DC to the microphones (if needed). They must have a decent DC/DC converter in there to take 5V from USB and be able to send 48V (admittedly only up to a maximum of 10mA of current) to power up to two connected active microphones. Once it was all open, I sat it on a plastic box, plugged the USB cable into my workshop computer, and my headphones into the output to monitor what was happening. Then I worked on the potentiometers. All four were scratchy and felt gritty, so I gave them a good squirt of contact cleaner while rotating them from end to end, making sure the entire track got a decent wet wipe. They quietened down a lot, and as there is no obvious dust inside the interface, it was likely worn pot track debris. I gave them another few blasts once this lot had dried. I moved on to the jack sockets. These are mostly enclosed by hard plastic mouldings, so getting access to the contacts inside was a problem. The barrel nuts on the outside of the socket are easy enough to tickle up, as they need to be taken off anyway, but I replaced them before cleaning. If these ferrules aren’t electrically clean, there’s not a lot of point doing the rest. What I needed was a means of cleaning the contacts inside, at least where jack plugs would touch. To this end, I took a timber dowel and glued very fine (1200 grit) wet and dry sandpaper around it, making it a snug fit inside the socket. After spraying the sandpaper with contact cleaner, a few gentle ins-and-outs and a twist or two cleaned the relevant surfaces, at least as much as I wanted to use abrasives on them. Then I blew out any debris after the cleaning rod work and sprayed with more contact cleaner to flush things out. Left: a Line 6 Toneport UX2 audio interface. Removing the barrel nuts on the headphone jacks reveals multi-pinned plastic antirotation washers. siliconchip.com.au Australia's electronics magazine June 2026  83 I repeated this on all the sockets and manually polished anything I could see and access with my diamond contact file. I cleaned the XLR connectors (not that I use them) with a bamboo skewer soaked in contact cleaner. It was the perfect size to fit in the holes in the socket. The probe came out clean anyway, so I considered that done. That was about as far as I could go with it. Other than the pots and sockets, there really are ‘no user-serviceable parts inside’. The audio tests after that were a lot better, but not perfect as far as the pots went. However, I wasn’t too keen on the prospect of desoldering anything from this circuit board, especially a through-the-board pot. For the amount of use this device gets now, I can live with it. At least now I know that if the pots continue to give me trouble, I can get the device apart easily enough and replace them. Fingers crossed it doesn’t come to that. The sockets all seem to be working well now, so I reassembled everything in reverse order for a final test. All was good, which was music to my ears! Simpson Contessa 425 washing machine repair I refurbished a Simpson Contessa 425 washing machine about four years ago. Since then, it has worked well. I had to repair the spin solenoid around two years ago (described in Serviceman’s Log, October 2022). Lately, it has been leaking water. This was not a major drama, as the machine is on the back verandah and the small amount of water just ran off the concrete onto the grass. It was more of an annoyance than anything. I had been meaning to check where the water was leaking, but every time I noticed it leaking, the machine was in use with water in it. I finally co-ordinated troubleshooting with my wife. I needed to pull the machine out and remove the back panel so that I could see exactly where the leak was. With the machine pulled out and the back panel removed, we added some water, and I could see that it was the water pump that was leaking. Water pumps are one component that I do have spares of, so I was confident I could find a replacement. I recalled that we had previously used a Simpson 7.5kg machine that was computer controlled. We used it for several years until the computer failed, so that was not economically repairable and it went to the boneyard. I located the machine and removed the pump. I then removed the pump from the 425 and compared them; they were completely different. The original pump was much longer and had the inlet on the top, whereas the possible replacement pump was much shorter and it had the inlet on the end. Therefore, the original drain hose was too short. But maybe I could use the hose from the 7.5kg machine. I went back to the boneyard and retrieved the inlet hose. Then it was time to see if the later-model pump and hose would fit in the older machine. I first checked to see if the bolt holes in the pump would line up with the holes in the back of the machine where the pump mounts. On the 425, there were four holes for mounting the pump; two of them lined up with the bolt holes in the replacement pump, so that was OK. After bolting the pump into the machine, I fitted the inlet hose to the pump and then to the bowl. It fitted correctly, with plenty of clearance to the pulley on the bottom of the bowl, so the pump transplant was a success. I decided to change the outlet hose at the same time, as the old hose had previously had some leaks in it, which had been repaired with duct tape. While this had been successful, I thought that the newer hose looked better, so I would use it. I connected the replacement hose to the pump and noticed that the new hose was a slightly smaller diameter, so I had to change the fitting where the outlet end of the hose is connected to the grey water disposal pipe, but that was easy and I then replaced the back panel. With the machine back in use, there were no more water leaks. The reason these old pumps leak is that the seal where the motor shaft enters the pump wears out. This is a special type of seal that is not available as a spare part. I have previously repaired these old pumps by swapping parts between them, like swapping a good motor onto a good pump, but there’s only so much I can do without being able to obtain spare parts. Bruce Pierson, Dundathu, Qld. Ozito QL09009A 5-cell lithium-ion battery charger The original (longer) Simpson Contessa 425 washing machine pump is shown above. The replacement pump is below, with the inlet located at the end. 84 Silicon Chip This Ozito battery charger had no output. It is a conventional flyback design using an AP8263 IC. The secondary side has an LM358 dual op amp that monitors the charging current and alters the drive to the feedback optocoupler to vary the output voltage of the charger. Australia's electronics magazine siliconchip.com.au From left-to-right: the AM05 & AM07 motor control boards; a brushless DC hair dryer motor; the drive signal from this hair dryer motor. There is a P-channel Mosfet in series with the output, which was not being switched on, hence the lack of output. There is also an unmarked 8-pin IC that seems to monitor the battery charging and drives a three-pin LED, giving a red or green light. Another output of this IC drives an NPN transistor that should switch on the Mosfet. I decided that the mystery IC was faulty, so I forced the Mosfet on by shorting out the NPN transistor. That got the charger working again. I assume the Mosfet was supposed to be turned off if the charging current got too high or charging took too long. It would help if the IC could be identified. Roger Sanderson, Fig Tree Pocket, Qld. Dyson bladeless fan faults (AM05 & AM07) The brushless DC motor circuit drive boards in these Dyson fans use a Power Integrations LNK304D buck regulator to produce 15V or 5V for the control ICs from the 350V DC rectified mains. Unfortunately, this part fails, feeding a destructive voltage through to the low voltage parts, particularly the microprocessor. Power Integrations now has an LNK3204D, which hopefully is more reliable. Replacement boards for these fans cost around $200, so it is questionable whether it is worth repairing them. Of course, the microprocessor that holds the software is not available as a spare part. I am looking at using an alternative brushless DC motor control board to power the fans. There are low-cost controller boards available, but they are designed to drive low-voltage motors. They have a built-in switch-mode converter to provide a low voltage for the motor and drive 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? It 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 cars and similar. 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. siliconchip.com.au circuit from the AC mains. To use them, the motor would also need replacement. Attached are photos of the AM05 and AM07 control boards. The AM05 uses an SMA6823 to drive the motor, while the AM07 uses individual Mosfets. I am also investigating using a brushless DC hair dryer motor from AliExpress to replace the motor and driver in a Dyson bladeless fan. Note that the drive signal on one of the three phases is not continuous, but is in bursts. The driver board provides three levels of airflow. As the airflow is increased, the driver pulse width increases, but the pulse rate stays the same. Roger Sanderson, Fig Tree Pocket, Qld. Samsung TV fixed the IT way We have a Samsung TV (UA55CU8000) and sound bar (HW-Q600C). One evening, as my wife settled down to watch one of her programs while I was occupied in another room, she called out that the sound was “not working properly”. When I came to check, I could see that using the remote would bring up the numerical data on-screen for the volume setting but it was obvious that the volume was not changing. As a quick fix, I jumped into the TV menu and enabled the TV speakers while disabling the sound bar. This worked, seemingly indicating a problem with the sound bar. The next day, I switched on the TV and re-enabled the sound bar. The remote still had no effect, but now the volume was changing, slowly upwards, without me doing anything! As part of my fault-finding process, I decided to transfer the sound bar to the small TV in the kitchen and see what happened. Well, of course it worked properly, didn’t it! I put the sound bar back while glaring sideways at the now-suspect TV. While I was doing this, the old computer adage of “Have you tried turning it off and on again?” came to mind. Since no modern piece of electronics is ever turned completely ‘off’, I pulled the power cord out of the back of the TV, waited a while and plugged it in again. When I turned it on again, everything worked correctly and has continued to work since. When we thought about it, earlier that evening we had a momentary mains power glitch, probably a little less than half a second. This appears to have addled the TV set’s brain, and a full power reset got it straightened out again. SC Ian Malcolm, Scoresby, Vic. Australia's electronics magazine June 2026  85