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SERVICEMAN’S LOG Water woes and hydration hindrances Dave Thompson As a kid growing up in Christchurch in the 1960s, we were always told that our tap water was the best in the world. This had been scientifically proven by men in white lab coats many times over the years, so it must have been true. It certainly looked crystal clear and had no twigs or mud (or worse) floating in it, so I had no reason to believe this wasn’t the case. As it turns out, it was true. This was due to the vast aquifers under the Canterbury plains, near to the city. There was more than enough for everyone, which included our relatively big city and many satellite suburbs, along with all the nearby farmers’ requirements. Many smaller towns in the locality all had their own wells and supplies, and the world was rosy, and we all loved each other. Fast forward to 2010, and everything changed. We had a series of huge earthquakes here; many people were killed or injured in some of them. Three fault lines all went at once – or within cooee of each other. While the scientists at the university of Too Much Time on Their Hands assured us the quakes were all unrelated, I thought that just didn’t make sense. Why would three faults, two of which were unknown at the time, all go off at around the same time? It beggars belief. We have been expecting “the big one” here for as long as I can remember. New Zealand is positioned in the “ring of fire” that stretches right around the Pacific Ocean, with a series of volcanoes, above or below ground, causing almost all of our seismic problems. The Alpine Fault is where the Australian and New Zealand plates meet, close to our southern alps; it is likely why those mountains formed in the first place. Geologists have been telling us for years that this fault will go off again one day, and it will likely devastate the country. Excellent! An Earth-shattering kaboom In September 2010, when I was almost thrown out of bed by a huge ‘quake, I thought it had finally come. But no, that quake was from a previously unknown fault just out of town. It happened at 4:05am, and while it caused some property damage and a few injuries – some major – it was mainly just property. We all heaved a huge sigh of relief, and rebuilding and normal life resumed. The problem was that all our aquifers were very close to where the fault burst, and this damaged them, so the water quality suffered. Then, just a few months later, a much more devastating ‘quake hit us from a different fault. It killed a lot of people and injured many more, some very seriously. It trashed entire suburbs, which will never be rebuilt. About a third of the city was wiped out. Buildings collapsed and facades fell, crushing people in the street. This one had the highest lateral acceleration ever measured in a ‘quake, likely because it was so shallow, and even though the magnitude figure was lower than the 7.1 in September the previous year, at 6.4, it was more devastating. 82 Silicon Chip Australia's electronics magazine siliconchip.com.au This also affected the city’s water supply. Aquifers under the city and reservoirs were cracked or destroyed, and corrupted by mud & debris. Many of the supply pipes also broke. As a result, many people were without water; we all suddenly had to rely on bottled water. Even worse, waste systems were also destroyed, so we needed portable toilets. I think every portable toilet and bottle of water in the country was sent here. We had no power for a week, but we did have gas, which we used to boil water for neighbours who didn’t. It was the worst of times, but it often brought out the best in people. My usual long-story-short is that now our water was not as good as it once was. Boil notices for tap water were issued, and sales of water filters went through the roof, with the local big-box store selling out in days. Many resorted to using BBQs and whatever else they could fire up to get clean water. The supermarkets rationed milk, water & bread, and petrol stations rationed petrol and LPG, with kilometres-long queues forming. The city water guys worked around the clock to get pumping stations back online and repair the infrastructure that had been ruined. In many suburbs, they ran heavy polythene pipes along the footpaths to get water to affected people. The power companies did the same, laying overground cables to get power to suburbs that were dark. It was an interesting time to live. Well, well, well The upshot is that our water supply has never been the same. A few years ago, the council decided to chlorinate the water, to much wringing of hands and gnashing of teeth. They claimed it would only be for six months, until they could sort any contamination issues. Keep in mind this is at least 14 years after the quakes. It wasn’t long before the familiar chemical smell permeated our water. It may well have been clean, but it wasn’t the water I grew up with. The first thing we did was install an under-bench filter system so that, at least, our tap water didn’t reek of chlorine. A client of mine who worked for city water said that it was temporary only while they sorted out the aquifers. Our water is sourced from a 400m-deep well just a kilometre from us, and it seemed fine before they added the chlorine to it. I know I can’t analyse it, but it didn’t look or taste any different. It turns out they did it to all water supplies here ‘just in case’. As I said, they claimed it was meant to be for a few months. Now it’s a permanent thing, and the water is disgusting, but only because of the chlorine, which they promised we ‘wouldn’t even notice’. Hence the need for filters. I’m not that happy about drinking chemicals every day, and that’s aside from the ratepayers’ costs we have to stump up for it year on year. A faulty filter Anyway, rant over. We have several water filtering devices in our kitchen now because one just isn’t enough. Under-bench filter systems are expensive to keep going, so we have a couple of standalone filters. One is a ceramic, two-part, bench-standing thing with a stone and ceramic compound filter in the top half. We pour water in that part and, at the rate of one litre per siliconchip.com.au hour, it drips into the bottom tank, which has a tap. This means we can draw clean, filtered and non-chlorine tasting water from there. It works well, but it only deals with a few litres at a time. When we take a jug full from it, we fill that same jug with tap water and pour it in first, so we always have a good supply, albeit some time later, since it takes so long to passively filter through. We also have another benchtop water cooler/heater type thing. It uses a similar filter system in the top tank, and any water drawn off is filtered, as it comes from the bottom tank. The unit has a hot and a cold tap, so we can have chilled water and heated water (but not boiling). It’s a relatively cheap appliance, and as a cooler, it is OK. As a heater, it is passable, but you wouldn’t get a steaming hot coffee using that water. The cooling and heating are achieved by a Peltier element, a cheap and effective way of achieving heating and cooling, using the Thermoelectric Effect. They aren’t that energy-efficient, but devices like this are passable and much cheaper than the alternatives. A proper water cooler uses refrigerant in a heat exchanger system and deploys a decent heating element for hot water. But this one is not that advanced. We mostly just use it for its cool(ish) water. The important thing is that it is filtered; we can always put ice in it, or fill a jug and put it in the fridge. Items Covered This Month • Water woes • Repairing a Beyonwiz DP-P2 video recorder • Getting around a water pump • Fixing a Bose SoundDock Series 1 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 Australia's electronics magazine July 2025  83 So, it is a useful appliance regardless of the inability to get water really hot or cold. I hear it occasionally go into cooling mode, and we can usually trigger it by emptying the filtered water reservoir and letting unfiltered water drip through the filter system. As soon as the water in the tubes below the tanks gets a little warmer, a thermostat triggers the relevant element to heat or cool. Peltier problems With a single Peltier element, simply reversing the polarity of the power supply dictates whether the element heats or cools. They are used in all kinds of mini fridges and food warmers, but it gets a little trickier in a water dispenser with both hot and cold functions. They could use complicated switching in order to heat one side and cool the other, or they can just use two Peltier elements, one for hot and one for cold. The latter is what I found here. The problem arose when we noticed the water was not being chilled anymore. When I tried the warm water, that side was working. I emptied the bottom reservoir and filled it with room-temperature water, but while the cooling fan kicked in, after half an hour, the water was the same temperature. This required a closer look. I emptied all the water, or as much as I could, unplugged the cooler and removed the vented bottom of the unit. As usual, there were security screws used throughout. It is not really a problem when you have the bits, so there’s no real ‘security’. In other words, it’s all a waste of time and money. The bottom came away cleanly enough and exposed a printed circuit board (PCB), along with the heating and cooling modules. This, surprisingly to me, was a wholly integrated unit, which consisted of side-by-side piggy-backed small water tanks, with inlet and outlet tubes. A Peltier element was mounted on one face of the tanks, and a CPU-type heatsink and cooling fan was mounted on each end. I guess the fans draw air from the elements rather than blow air through the heatsinks. Either way, I’d never seen anything like this before. I mean, I’ve played with Peltier elements – I can buy them at Jaycar, for example, and found them interesting to experiment with. But I have not seen them used like this. The difficulty I was facing was that the elements are glued to the water tanks with something that, by the looks of it, is military-grade adhesive. Some gentle persuasion proved it wasn’t going to let go easily. I guess I could have literally scraped the element off, but that was going to be too messy. And what could I use to stick it back on with? Some kind of heat-resistant epoxy? 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. 84 Silicon Chip This was starting to look like it wasn’t worth investing more time in. I deduced this could be a standard type of part for these big box cooler/heaters and so hit the Chinese sites for a similar part. True to form, there were literally hundreds of all different types and styles for sale there. I filtered (har!) out the ones that might work, just based on looks alone, and found a few that handily had measurements listed with them – most don’t. As there were no part numbers anywhere on this one, that made it a little more difficult. The old switcheroo I jumped to the conclusion that the voltage and current supplied to the elements would be pretty much the same as all the others, so it was simply a matter of finding an assembly that was around the same size and fitted inside the space. It would also be a bonus if the mounting holes lined up, but I could work around that. With no specific mounting measurements listed, it was a gamble, but since the overall sizes and shapes were reasonably consistent between the ones I was looking at, I felt confident one would fit OK. I doubted whether this appliance manufacturer – a cheaper brand – would use something other than what was inexpensive and readily available. I took the plunge and ordered a replacement that looked pretty much identical to mine and waited the usual months for it to make its way here. It eventually did arrive. At least the filter side of the thing still worked, even if it didn’t cool the water. The new assembly was very close to the old one. The biggest hassle was taking off the single-use clips from the soft rubberised water hoses. These must have been put on with a machine of some type, so I had to carefully cut them off without damaging the hoses beneath. I didn’t want to have to replace them, too. The module had been hard soldered in – I guess they couldn’t stretch the manufacturing budget to some PCB connectors. It was simply a matter of mounting the new one and soldering the wires to it. Two of the holes lined Australia's electronics magazine siliconchip.com.au up, but the others didn’t. Although I could only use two of the four, the module was solidly mounted. The acid test was plugging it in, filling it with water and firing it up. The fans came on as the switch was toggled, and all the usual lights came up to show it was heating and cooling. I left it for 20 minutes, checking occasionally for the usual burning smells and any indication that things were not happy. It seemed OK, and the water was cooling. After a while, the fans stopped, so I assumed things were up (or down!) to temperature. I replaced the bottom cover and put the unit back into its usual position and it has been running now and cooling the water for months, so I consider it repaired. At the end of the day, though, it would have likely been cheaper and less hassle to just go and replace the whole unit. But, that means the rest of this one would end up in a landfill somewhere, so it is a mixed blessing that we can at least buy a part that will work in it. Again, it wasn’t essential that this thing cooled the water; we really just use it for filtering, but it irks me that something would fail after a relatively short time, no matter how inexpensive it may have been to buy. The Serviceman’s Curse required I at least tried to repair it and get it back in working order! Beyonwiz DP-P2 PSU repair I found a listing on eBay for a brand new Beyonwiz DP-P2 personal video recorder (PVR) for $20 plus $20 postage. I thought that was odd, as this model is now more than 10 years old. Also, a working DP-P2 is worth more than $100; even one in non-working condition is worth more than $20. I wondered if it was a scam, so I sent my mate the link with the subject “Too good to be true”. Imagine my surprise when he emailed me back and said he’d bought it! He said because it was so cheap, he took the chance on it and even if it was a scam, he could get his money back with PayPal anyway. A few days later, he emailed me to say that the unit arrived, but it was not brand new and it had no remote or anything else with it, just the PVR. When he connected it and turned it on, it came up with ERROR 0000. I told him to take the lid off and look at the power supply board to see if there were any bad capacitors. He emailed me back that they all looked fine. A high percentage of failures in these units are caused by bad capacitors; I’ve fixed many. He suggested sending the unit up for me to have a look at, but I said the postage cost is too high; I said to just take the PSU out, send that and I will have a look at it. I would see if I could fix it, but there were no guarantees. A few days later, the power supply board arrived. I could see that six large electrolytic capacitors had been replaced, three of which were a larger physical size than the originals. The soldering was good and there were no dry joints on the board, so it would be a tricky one to fix. When I had some time, I got out one of my working DP-P2 PVRs and fitted my mate’s PSU into it. Sure enough, it came up with ERROR 0000, so the PSU was definitely faulty. I got the board back out and started checking it over. I first tested all the diodes with my in-circuit transistor and diode tester, and they all tested good. On one of my other PSU boards, I’d found that D12 and D13 (UF5402 200V siliconchip.com.au Australia's electronics magazine July 2025  85 ultrafast diodes) were faulty, but on this PSU board, they were still good. The next things to check were all the electrolytic capacitors. I grabbed my ESR meter and started testing them. I’d recently repaired a DP-S1 PSU that had six faulty small capacitors. Checking over this DP-P2 PSU board, I found that most of the capacitors were good, but C7 and C11 (both 50V 33µF types) read very high at around 5W when they should be less than 1W. I checked my salvaged capacitors, but I did not have any of this value. Then I remembered that I may have purchased this value some time ago and, on checking my new parts, I found them. I replaced the two capacitors and put the PSU board back in the PVR and switched it on. This time, it came up showing Channel 7 Melbourne on the front display. I connected the HDMI cable to my HDMI switch and turned on the TV. I checked the hard drive, and there were several recordings, so I skimmed through a couple of garden shows and everything worked fine. Then I connected up the aerial and tuned in the local channels. So, my mate’s PSU was now working and I could send it back to him. While I had this PVR out, I had a look at the three DP-P2 PSUs that I had not yet fixed. I’d noted on them which voltages were missing and I’d taken the 12V regulator out of one of them in the course of troubleshooting it. This just happened to be the PSU that I’d replaced D12 and D13 on. I looked at the other two non-working boards as to which voltages were missing and I determined that the 12V regulator on one of the boards should be good, so I removed it and fitted it to the PSU that I’d replaced D12 and D13 on. I fitted the PSU to the PVR and turned it on. It now worked, indicating that my previous troubleshooting (which I hadn’t got back to) had found the last faulty component on this PSU. Looking at the other two units, I ordered some parts on eBay that I suspected of being faulty on these boards. I will get back to them when the parts arrive. Time came to post the PSU back. He received it a few days later and fitted it to the Beyonwiz DP-P2 PVR, and he reported that it is now working correctly. This was another win for both of us. Bruce Pierson, Dundathu, Qld. Water pump workaround About a year ago, we had a lightning strike in our backyard at about 1am. The EMP tripped the main circuit breaker. We discovered the extent of damage the next day, which included a damaged workshop air conditioner, the NBN box, oven, printer and the water tank pump. Lightning had actually struck a tap that was connected to the pump. It was covered by insurance, but we never got around to fixing the water pump. The tank is on the high side of the block, so gravity feed is adequate for the low side. It has been on the back-burner for a year, but I finally got around to looking at it. As it turns out, the motor survived, but the control electronics were completely blown apart. As with most devices these days, getting a spare was impossible; you can only buy the whole assembly. The photo of the control board shows how much damage several thousand volts will do. Some years ago, I bought a couple of remote control modules. These run from a 12V plugpack and the relay switches up to 10A, more than enough for the motor. I forgot why I bought them and they were never used. I put the module inside a plastic box attached to the wall next to the water tank; it is under cover so there was no need for waterproofing. The remote range is not great, about 20m, but that’s adequate. So now I can switch the pump on manually if it’s needed. I then added a mains timer for the plugpack to limit the time the pump is on. Instead of spending about $300 on a new pump assembly, the repair cost was effectively zero, as I already had all the bits. Charles Kosina, Mooroolbark, Vic. Bose SoundDock rejuvenation My daughter was cleaning out her garage and found an old Bose SoundDock Series 1. She suggested that it would be nice to get going again as the sound from it was very good. So I ended up with another job. The SoundDock looked in good condition, but there was no power supply or remote control. The SoundDock was designed to have an original iPod with a 30-pin connector plugged into it as the music source, but that was long gone. I found a Bluetooth receiver on the internet that was designed to replace the iPod, so I ordered it. I remembered repairing the power supply some years ago; it was a ±18V unit. I figured I could find two suitable power packs in my box of spares and get it going. I found the correct pin information on the net and connected the power packs. I plugged the Bluetooth module in and applied power. The LED on the module The power supply from the Beyonwiz DP-P2 personal video recorder. 86 Silicon Chip Australia's electronics magazine siliconchip.com.au The photo at upper left shows the water pump assembly, while the photo above is of the very obviously damaged control board. The adjacent photo shows one of the remote control modules that I had lying around. The relay in these modules are rated up to 10A, making them perfect for this motor. did not even light up, so it was not getting power. I decided to test the Bluetooth module separately, so I found an old iPod charging cable and connected the Bluetooth module to it. The LED lit up, and I was able to connect my phone to it. So it looked like there was no power getting to it when it was plugged into the SoundDock. I removed the covers from the SoundDock and found some components that had obviously overheated. With no circuit diagrams, it would be a nightmare to repair. I had a 30W + 30W stereo amplifier board left over from another project, and it looked like I could fit it in place of the original amplifier. I connected the new amplifier to the speakers and wired the output of the Bluetooth module to it. Once connected to my phone, the audio output was quite acceptable, so it was just a matter of fitting the new amplifier in the existing case. I made a sheet metal plate to fit and screwed the new stereo amplifier in place. I wanted to keep the original input board with the 30-pin connector, so I found some information about it on the internet and wired the audio out to the new amplifier. I decided to use a 12V 2A power pack, so I had to add a 7805 regulator to drop the 12V to 5V for the Bluetooth module. I put it all together and discovered that the Bluetooth module produced an audio announcement saying it was powered up and connected, but the audio level was way too high, so I attenuated both channels using a resistor divider network to give only 25% of the original signal level. The actual music level could be controlled by the audio player on the phone. Finally, I designed and 3D-printed a plate to fit around the Bluetooth module socket and fitted a power connector to the back so the plugpack could be easily disconnected. Now we had a great sounding music system for my daughter’s study. SC John Western, Hillarys, WA. The internals of the Bose SoundDock is shown above with a close-up shown at right. siliconchip.com.au Australia's electronics magazine July 2025  87