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SERVICEMAN'S LOG I’ve repaired planes before, but never tanks Dave Thompson Some jobs require a great deal of patience and involve plenty of introspection. Did I do the right thing? When is the right time to call it quits? This is one such story, illustrating the pitfalls of my life as a serviceman. In the years that I have been The Serviceman, I have tried to keep this column from being too computerrepair centric, mainly because computers are quite boring to many of the service people who read this magazine. However (there’s always a however!), a repair I’ve had on the boil for almost a year now illustrates just how fickle the business can be, and how much we rely on others to do their jobs properly to have a successful outcome. I’d call this one a cautionary tale. It all started a long, long time ago in a galaxy far, far away (not really!) when a regular customer brought me a machine I was already very familiar with; a Dell Alienware M18X gaming laptop. The Alienware range of Dell laptop computers is well-known for their blistering performance. Therefore, they are a very sought-after machine within the gaming fraternity (and sometimes ‘power users’ too). As with any high-performance laptop, all this muscle doesn’t come cheap. My client bought his Alienware laptop in the USA when he was siliconchip.com.au travelling there some years ago. Even though it was ‘on special’ at the time, he still paid around $US6,000 for it, a staggering sum of money for a laptop at the time. It’s luggable, all right $US6,000 buys a lot of hardware, and this Dell is no exception. The computer boasted the likes of twin accelerated (and upgradeable) graphics cards, dual RAIDed hard drives and a high-definition 17-inch screen, a relative rarity at the time. To call this machine a ‘laptop’ is perhaps a bit disingenuous; it’s built like a tank. I certainly wouldn’t want to carry it around with me and plop it on my lap, given it weighs around 8kg. It is more of a ‘desktop replacement’ computer, intended to sit in one place most of the time, not be lugged around as one would a more ‘typical’ laptop. To give this some context, I took a standard Acer laptop with me on a trip to Europe a few years back, and by the third week of our travels, I was so sick of carrying it around I was seriously Australia’s electronics magazine Items Covered This Month • Servicing is often a tankless job • Pool pump filtration system • • failure Replacing shorted schottky diodes Fault-finding an audio level meter kit by ETI *Dave Thompson runs PC Anytime in Christchurch, NZ. Website: www.pcanytime.co.nz Email: dave<at>pcanytime.co.nz ready to drop it in a rubbish bin at Frankfurt airport. I can see the advantages of tablets! Even with a nice laptop bag, it was such a hassle to take everywhere with us. That’s even ignoring how much of a pain it was to take it through the customs checks in European airports, where customs officers seem to assume that every laptop is a disguised bomb. I almost ditched our laptop due to its weight and size, and in fact, I ended up leaving it in Croatia, where we spent most of our time over there, rather than lugging it back with us. That was an everyday laptop with a then-standard 15-inch screen; this Alienware thing I had in the workshop weighed at least three times as much, and the ‘bag’ that came with it looked (and felt) more like a shoulder-borne suitcase than a laptop bag. So, it’s a very large and well-appointed gaming laptop intended (I assume) to be sat on a desk and not moved unless absolutely necessary. I’ve worked on this machine before, mainly to rectify the odd software/ operating system glitch or similar small-fry stuff. Nothing too serious. July 2021  91 But then the owner brought it in one day last year with a problem; he’d lost video output, but just before that, the hard disks could no longer be ‘seen’ by the computer, and he was having that old chestnut “disk boot failure” message. A crash course in RAID While a common enough message with standard machines, the fact he had two hard drives in a RAID configuration made this a little more atypical, and not a good sign. RAID stands for either “redundant array of independent drives” or “redundant array of inexpensive disks”, depending on whom you ask. RAID is not just a fly spray; it is a range of configurations used by computer people to ‘gang up’ hard drives. A server machine, for example, might spread its data storage over several separate disks, or ‘mirror’ data over many disks, so not all their eggs are in one basket. 92 Silicon Chip The theory goes that if one hard disk fails (as they are wont to do), the others should still have a copy of the data and business can continue until the faulty drive is replaced (usually via a hot-swappable drive bay). The whole RAID thing is way beyond the scope of this column; needless to say, the way the twin hard disks in this machine were configured meant that data reads and writes were split between the two disks (known as striping), and this makes for excellent performance. The read speeds approach twice that of a single drive. Many gaming machines use this type of RAID configuration, but the biggest disadvantage is that if one drive fails, everything screeches to a halt, and all the data is gone (unless it has been backed up which is, of course, always a good idea). I feared the worst when the guy brought the machine in. My first assumption was that one of the drives had failed and all we’d have to do is Australia’s electronics magazine kiss his data goodbye, provide a new drive and reinstall Windows and his software and games on a rebuilt RAID. But no, there was something else afoot. A regrettable decision It turned out that he’d taken the machine to another repair guy first. This often happens with servicemen, and there is nothing much we can do about it. Customers can take their devices anywhere they want, and while it might sting a bit, such is the life of a serviceman. I’ve moved from several different parts of town over the years, sometimes due to the quakes and sometimes just because we moved house. While some customers will follow me, some will not, and I understand completely. I certainly don’t begrudge people’s decisions to go somewhere else; they might not be happy with my work, or, like in this case, they might live a fair way out of town. While once my workshop was a lot closer to him, it is now siliconchip.com.au much further away. He ended up taking this machine to a more local guy rather than trudge all the way across the city. The problem is that the local guy mustn’t have been very careful because as he pulled the hard drive assembly (consisting of the two hard drives) from the motherboard, he tore the flexible PCB ‘strap’ that connected the twin drives to the computer. Not only did the strap tear, leaving part of it behind still trapped in the socket, but he’d also yanked on the connector on the motherboard, which looked to have come unseated, damaging the tracks and rendering the board basically useless. He’d simply put it all back together (there is an easily-removed and replaced cover that exposes all this stuff) and given it back to my guy claiming it was ‘dead’. He brought it to me for a second opinion and, after my diagnosis, was more than a little miffed at being charged $150 by this siliconchip.com.au other guy essentially to wreck his machine. I said I’d see what I could do. It turns out that I couldn’t do much. Spares for these ultra-performance laptops are not readily available, especially those of this age. Dell couldn’t help, so it was down to me searching the second-hand market for parts. Sourcing new parts The first challenge was finding a suitable hard drive connector. As it turned out, AliExpress had plenty of vendors selling the part, and even though it was pretty expensive ($US65), I promptly ordered one while I got on with the rest of it. The vendor I bought it from had several other Alienware parts listed, so I bookmarked that page just in case. The part arrived six weeks later, but it was the wrong one. They’d sent me one for a three hard disk array; while I initially thought perhaps I’d be able to use two of the connectors, the connection to the motherboard was very different. Australia’s electronics magazine This is the most frustrating thing about buying from China; if they sent the part shown in the product picture and the specs below it (which we all tend to buy from), it would be fine. As it was, this part was useless. After the usual to and fro dealing with the vendor, they sent another one, the right part this time. In the meantime, I was trying to remedy the broken socket on the board. This is one of those PCB-mounted sockets with a flip-down ‘bar’ that, when toggled to the top, locks the flexible connector in once it is fully seated. The other guy had simply pulled the strap out, breaking the connector, tearing the flexible strap and, by the looks of it, lifting some PCB tracks. This wouldn’t be easy to fix. While the sockets are available from the usual suspects, I had no means of repairing something like this. I didn’t know how deep the damage went, and I could spend hours trying to resolve this for no good outcome. I bit the July 2021  93 Helping to put you in Control ECO PID Temperature Control Unit RS485 ECO PID from Emko Elektronik is a compact sized PID Temperature Controller with auto tuning PID 230 VAC powered. Input accepts thermocouples J, K,R,S, T and Pt100 sensors. Pulse and 2 Relay outputs. Modbus RTU RS485 communications. SKU: EEC-022 Price: $104.45 ea Mini Temperature and Humidity Sensor Panel mount Temperature (-20 to 80degc) and Humidity (0 to 100% non condensing) sensor, linear 0 to 10V output. Cable length 3 meters. SKU: EES-001V Price: $164.95 ea ESM-3723 Temperature and RH Controller 230 VAC Panel mount temperature & relative humidity controller with sensor probe on 3 metres of cable. It can be configured as a PID controller or ON-OFF controller. 230 VAC powered. Includes ProNem Mini PMI-P sensor. SKU: EEC-101 Price: $619.95 ea PTC Digital ON/OFF Temp Controller DIN rail mount thermostat with included PTC sensor on 1.5m m lead. Configurable for a huge range of heating and cooling applications. 230 VAC powered. SKU: EEC-010 Price: $98.95 ea Ursalink 4G SMS Controller The UC1414 has 2 digit inputs and 2 relay outputs. SMS messages can be sent to up to 6 phone numbers on change of state of an input and the operation of the relays can be controlled by sending SMS messages from your mobile phone. SKU: ULC-005 Price: $228.76 ea 20% off! 4 Digit Large 100mm Display Accepts 4~20mA, 0~10Vdc, is visible 50m away with configurable engineering units. 10cm High digits. Alarm relay and 230VAC Powered with full IP65 protection SKU: FMI-100 Price: $1099.95 ea Touchscreen Room Controller SRI-70-BAC Touchscreen Room Controller are attractive flush mounted BACnet MS/TP controllers with a large colour intuitive 3.5” touchscreen for viewing the system status and modifying the settings. SKU: SXS-240 Price: $306.90 ea For Wholesale prices Contact Ocean Controls Ph: (03) 9708 2390 oceancontrols.com.au Prices are subjected to change without notice. 94 Silicon Chip bullet and told my client that he needed another motherboard if this thing was going to run again. He was actually fine with this, and asked if we could take the opportunity to upgrade the video cards for better performance. I checked with the vendor I’d been dealing with, and he’d listed a couple of uprated graphics cards. Not cheap at several hundred bucks each, but the client agreed, so I ordered them along with a used motherboard. The spending on this job was getting huge, so I hoped what we got from overseas would be fit for purpose. I also requested a progress payment, something I very rarely do. But as the bill for parts was already nearing a grand, I thought it prudent. The bottom line was that my client loved this special machine and wanted it to work again; as a serviceman, this is always my goal as well. All we could do now was wait for the parts to arrive. Given that the pandemic had just started and flights were on and off, it took several months for the parts to arrive. When they did, it was the video cards first, then eventually the motherboard turned up. Many vendors post a video of the parts working on the test bench, possibly to ensure there was no comeback if something didn’t work. In this case, the vendor didn’t show anything. I received the board, well-packaged, and assembled the machine. Not a good sign When I fired it up, I had no video, which was the client’s original problem when he took it to the other guy. No matter what I tried, I couldn’t get any video output. The built-in HDMI port had nothing, with or without the twin removable video cards installed. Something was off. As was typical, dealing with these guys in China was problematic. I’d spent many hundreds of dollars but couldn’t get a straight answer. The board looked to be faulty, and I arranged to send it back; a not inexpensive task. Another month or two went by waiting for them to receive the board. They did get it, which was a miracle, as I’ve sent several things back over the years and not one has arrived at the address provided by the vendor. I didn’t hold much hope for this shipment either. To be fair, it did arrive, and the vendor sent another motherboard, which took the usual two months to get here. My client was extremely patient, and hats off to him for being so understanding. My hands were tied; there is not much I can do in situations like this. Given the pandemic and the fact that the usual lines for parts are closed or delayed, we didn’t have many options. The new board duly arrived. Again, I reassembled the machine and installed the graphics cards and other bits and bobs. I left the top of the case off so that I could see what was going on. On power-up, there was a puff of smoke; it came from one of the video cards. My heart sank. Now I didn’t know whether the graphics cards were faulty or the motherboard. Perhaps the last one had been OK too? This was a chicken and egg situation. I’d need knowngood graphics cards to test the motherboard, or a knowngood board to test the graphics cards. As it stood, I didn’t know what was good and what wasn’t, and I’d possibly just toasted a $500 motherboard. The serviceman’s lot is not always easy, and in this case, things were turning from bad to worse. What do I do now? Australia’s electronics magazine siliconchip.com.au What I did was pull the plug. I’d gone about as far as I could with this job. It was just under 12 months that I’d had it in bits on the bench. I dreaded calling my client and telling him the news, but I had to anyway. It’s the way of the serviceman. Knowing when to pull the plug on a dead-end job is something we all have to learn. If we don’t know that point, we’ll end up wasting time and money on something that isn’t achievable. He was surprisingly OK with it and quite philosophical. He was aware of the ups and downs of buying from overseas, and I’d made it clear along the way that we were buying second-hand parts, and things might not work out. He’d purchased another machine in the meantime, so at least he was up and running. While he had a lot of sentimental affection for this old Alienware machine, he accepted that sometimes it just isn’t feasible to carry on. He was also happy to pay the costs of the hardware I’d purchased. I didn’t add anything to those costs, and donated my time (he was a loyal client). I just wrote off the rest as one of those things that happens to a serviceman now and then when a job turns sour. As a result of this long-time saga, I wound up with some of the hardware. Whether I can move it on or use it anywhere is in the hands of the computer Gods. I did transfer his data and photos to his new machine (again not charged for), and he was happy, even though his beloved Alienware laptop was dead. I was relieved that we’d found a middle path and that he had everything salvageable from the old machine. Whether I will see him again, I don’t know. I did my best, and if he wants to take his new machine elsewhere, so be it. I’m not in business to lose money or clients, but sometimes things just don’t work out, and external forces can make or break a job. Whatever happens, life goes on, and the next phone call could be a great job or a real challenge. That’s the life of a serviceman. Pool pump filtration system failure A. H. of Attwood, Vic, had a recent problem involving some rain and a lot of mud. The problem continued with the inability of his pool’s filtration system to cope, leaving him with a pool pump that needed a repair... While away on business, it rained what can only be described as mud at home. This rain-mud turned our pool into a murky red-brown colour. For reasons unknown to me at the time, the pool filtration system didn’t cope. Fast forward a few days, and when I had my first chance to look at the pool, it was now a most unpleasant red-browngreen colour, and the bottom couldn’t be seen. Obviously, something fairly serious had gone wrong with the filtration system. Checking revealed the Chromatalyser complaining that there was no water flow for it to carry out sampling for Chlorine/PH levels. This was strange, as the system is fully automatic, injecting acid as required as well as controlling a Chlorinator to adjust chlorine levels. Overriding the system and turning on the filtration pump revealed a distinct lack of motor noise and an “Err64” message. This pump is a 9-star energy efficient variable speed Hayward Tristar model SP3215VS and is an absolute beaut when it works. The pump operating manual revealed that “Err64” is apparently an “Internal Short Circuit Failure”. siliconchip.com.au Australia’s electronics magazine July 2021  95 This sounded pretty ominous, although Hayward’s cure for this fault was to turn it off and back on, which of course didn’t help. So I was now up that well-known creek without a suitable motive implement. A weather forecast of 30-40°C for the next few days, with the wife and kids insisting that they would need to use the pool, meant that I had to fix it immediately, if not sooner. So I was forced to shell out over 1500 Aussie dollarydoos for a replacement pump. With the new pump installed and running, the pool returned to normal crystal clear water within a day or so. With that crisis averted, my attention turned to the old pump turned doorstop. Hayward pumps are very serviceable and easy to fix, but the electric motors that drive the pumps are not. In fact, there is no parts breakdown for the motor assembly at all, just the pump section. My admittedly limited knowledge on variable-speed drives made me think that the power switching module, or similar, would most likely be the culprit. So I commenced ripping the control box that was mounted on top of the motor apart. This revealed a circuit board with many components on it, but no power switching module. Inspection revealed a few connectors going into the bowels of the motor, where another circuit board was located. While playing around with this top board, something went “pfzzzt”, and the motor was completely dead. No display, no “Err64”, nothing. This top board appears to be a power 96 Silicon Chip filter/power factor correction/high voltage DC supply/soft-start device. It magically creates over 300V DC which is sent to the lower board. A 12V DC supply rail is returned to the top board for power as well as some switching signals for the soft-start relay. So it was time to gain access to the motor internals. Unfortunately, the manufacturer of the motor had used those stupid headsnaps-off-when-correctly-torqued type of bolts, which meant that they couldn’t be undone. A hacksaw made short work of that, and the motor split apart to reveal its secrets. I checked the motor windings and found no problems, so my attention turned to the internal circuit board. I expected to see a spectacular mess, but no, the board was remarkably clean with no noticeable damage. Unbolting it from the housing and turning it over revealed a “Dual Inline Intelligent Power Module” (IGCM15F60GA). Sure enough, desoldering and resistance-checking this module revealed a short circuit between the “Motor V-Phase Output” pin and the “V-phase Low Side Emitter” pin. So it looked like my hunch was right. Further troubleshooting on the top board revealed a low resistance between Vcc and the S-GND pin on the power factor corrector SMD IC (L4981BD). This was dragging the 12V DC rail down and shutting down the whole pump. Removing this IC returned the pump to its original “Err64” condition. I had nothing to lose, so I placed an order for a new IC, power module and Australia’s electronics magazine some bolts. A week later, the parts arrived, were soldered into place and the motor roughly slapped together for testing. At power-on, I was rewarded with the sweet sound of a motor spinning up to 3000RPM. Success! I reassembled the whole kit and kaboodle after a careful inspection of all the pump seals etc. I checked it for faults with my PATS tester (all good!) and reinstalled it into the filtration system for testing, where it has now worked for three weeks with no faults. For a total cost of around 30 bucks, I now have a working spare pump. I will probably never need it, but Murphy’s Law dictates that if I sell it, the next day the operating pump will cark it, and I’ll have to come up with another $1500... Replacing shorted schottky diodes in equipment R. S. of Fig Tree Pocket, Qld, has a couple of servicing stories, one about parts he has found to fail frequently, and another about turning two dud devices into one good one... I am finding many failed 200V schottky rectifier diodes in equipment that I am repairing. Hopefully, the manufacturing process for these diodes has been improved since these ones were made. Samsung monitors can have a shorted MR5200 (5A, 200V) in the power supply. There are two of these diodes in parallel. Sometimes one will siliconchip.com.au short out, stopping the monitor from working. Ryobi battery chargers (BCL14181H) also have two MR5200 in parallel, and one can short out. These chargers can also have a shorted P-channel FET (which feeds the charging current into the battery pack). The Dyson charging plugpack (Salom Model 17350-05) can have a shorted MR2200 (2A, 200V). You can crack these plugpacks open in a vice. Strangely, these have three output connections: 0V, 16.75V and 24.35V. The other Dyson plug pack (Model 205720-05) has only two connections, 0V and 26.1V. Dyson DC35 motors are a brushless DC motor, with a permanent magnet rotor driven by coils on the stator, powered by two half-bridges. The rotor has only one bearing at the fan end. As there is no bearing at the motor end to centre the rotor in the stator, mechanical inaccuracy can cause the rotor to rub on the stator. The motor then just buzzes but does not turn. To get the plastic back off the motor, hold that part in a vice, and then grab the rest and pull. I found this worked better than trying to pry it off, which damages the plastic. The first motor I came across was rubbing, and it was difficult to centre. Sometimes it would work, and then it would not. The second motor had a fault on the drive board with one of the components sending up a wisp of smoke. So I took the drive board (which includes the stator) from the first motor, and put it in the second motor. The two large capacitors on the drive board have glue on their tops and must be pried loose. You only have to resolder the power connections. This was successful, resulting in one good motor. I noticed the second motor was better mechanically than the first, with larger mounting screws for the board, so the design may have been modified during production. The adjacent photo is the power supply board for a Dell U2414Mb monitor, showing yet another example of a shorted schottky diode fault. The 150V, 8A SB8150 used for D702 at left had failed; I replaced it with a 5A, 200V rated SR5200. Editor’s notes: 200V is at the high end for schottky diodes, which more commonly are rated for a PIV in the range of 20-100V. So perhaps they are siliconchip.com.au The power supply board for a Dell U2414Mb monitor which shows an example of a shorted schottky diode circled in yellow. pushing the process to its limits, resulting in more failures in service. As for the Dyson plugpack with two output voltages, perhaps this suits two different vacuum models with different battery voltages. Fault-finding an ETI LED audio level meter kit N. B. of Wollongong, NSW, ran into a problem putting together a kit when he had built several others of the same type successfully. The solution turned out to be simple, but hard to believe... Over the years, I have assembled several kits of the ETI Bargraph LED audio level meter. The kits cost about $33.00 and took about half an hour to assemble. They all worked well, except the most recent one which I assembled some years ago. It wouldn’t work, so I put it aside and forgot it till recently. I then needed an audio level meter for a project, so out it came. I checked and rechecked everything, and it all Australia’s electronics magazine seemed fine, but it still didn’t work. Signal was getting to the processing IC; all voltages were as expected. I had a spare processor, so I fitted it, expecting it to work. It still didn’t. I then did a diode check on the display bar with its 10 coloured rectangular LEDs, seven green and three red. They all checked out OK. Out of desperation, I decided to compare the LED bar assembly on the board with a new one which I had recently bought. The bar is a preassembled commercial unit. To my amazement, I discovered that the LEDs were all inserted in the escutcheon bar the wrong way around! I desoldered the whole thing and found that I could coax the LEDs out of the escutcheon bar with a pair of longnose pliers. I refitted them the right way around, resoldered the bar to the PCB and hey presto, it worked! I must confess that I felt a great victory in finding that fault. SC July 2021  97