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SERVICEMAN'S LOG When things go wrong – really wrong Dave Thompson Sometimes a job comes along which seems like it’ll be straightforward, but really isn’t. This can happen even if that job is well within your field of expertise. Here’s one story where everything and anything seemed to go wrong. If you’ve read my previous columns, you will know that I started out servicing planes for Air New Zealand and then later, moved on to computer repair, which mainly involves swapping modules and fiddling with software. While I have repaired plenty of other electronics, especially audio gear (as I’m a bit of a muso), I’m still essentially an amateur serviceman in fields outside of those two. While I have repaired (and sometimes failed to repair) everything from an abacus to a Zimmer frame, my main focus for the past 25 years has been computers, with the odd curly job fired my way. As something of a keen amateur, I am not shackled too tightly to the conventions (and regulations) that real servicemen are legally and technically required to abide by. That’s not to say I’m a cowboy; far from it. With all the work I do, I always strive to adhere to the relevant standards and codes of practice. After all, they have typically been put in place to ensure safety and integrity. Before doing anything unfamiliar, I do my best to research the task ahead. For example, I wouldn’t just decide one day to re-wire my house. I could probably do it successfully, but I wouldn’t take the risk. All the re-wiring work I’ve done has been under the supervision of a 62 Silicon Chip qualified electrician who has then inspected and signed off on it. It would be madness just to pile in and do this type of work without some oversight by a professional, yet plenty of DIYers do. In many cases, no harm ensues, but if it all goes wrong, the house burns down, and maybe someone along with it; an outcome I find unthinkable. But sometimes a job comes along where despite being well qualified for it, it all goes wrong anyway. I think we have all had Australia’s electronics magazine those jobs where, in retrospect, they seemed doomed from the start; no matter how hard you try to dig yourself out of the hole you’re in, the hole just keeps getting deeper! While these jobs are thankfully few and far between (for me at least!), I’ve had a few over the years, and the following tale is one of those cases. This happened many years ago and did more to educate me on obtuse points of consumer law, and just how far some companies will go, than anything before or since. I’ll set the scene, and you can decide siliconchip.com.au Items Covered This Month • • • • The trials and tribulations of fine print Sony 8FC-100W digital clock radio repair Daikin aircon repair USB flash drive repair *Dave Thompson runs PC Anytime in Christchurch, NZ. Website: www.pcanytime.co.nz Email: dave<at>pcanytime.co.nz whether or not the chips should have fallen the way they did. It all started so innocently It began when I received an urgent call from a client who ran a high-profile car sales yard in town. I’d been looking after their office computers for a year, after taking over that task from the retired tech who’d set up their offices. Due to their importance as a client, I always tried to do any servicing or maintenance as promptly as possible. They had half a dozen sales staff, a receptionist and the owners on-site, all of whom had their own desktop-style workstation. These were all networked together in a semi-typical ‘star’ configuration, where each computer runs its own version of Windows and grabs important business files via mapped drives from a designated central server machine. This server should ideally be a purpose-designed unit with redundant power supplies, RAID-configured, hotswappable hard drives and a dedicated server operating system such as Linux or Windows Small Business Server. But in the real world, such machines can be pretty expensive to buy and maintain, so many small businesses just use a standard PC in a server role instead. This car yard was no different; their server was one of the owner’s machines, set up with the necessary drive and file shares. This made some sense, as it was the most powerful computer in the office. As such, all the scanning, printing, photo-processing and faxing jobs were done on or through this machine over the network. This type of configuration usually works well and as long as nothing particularly challenging happens, and siliconchip.com.au backups are being kept, disaster recovery isn’t too much of a problem, even if the server goes down. The backedup data can simply be copied to and shared on any of the other machines, networked machines’ mapped drives adjusted and life goes on. On that fateful morning, I got a call that the owner’s machine wouldn’t start and they were dead in the water. Could I come and take a look? Fortunately, they were only a few blocks from my then-workshop, and they were visibly relieved when I turned up within around ten minutes. As it was still early, there weren’t many tyre-kickers around, and thankfully there wasn’t much for the staff to do but sit around drinking coffee and talking cars (or rubbish!), so I had some breathing space. As described over the phone, the machine wouldn’t fire up at all, and it looked for all intents and purposes to be completely dead. In situations like this, I usually take the machine back to my workshop where I can properly troubleshoot it, and that’s what I did. On the bench, it appeared Christchurch’s notoriously rubbish postquake power supply had claimed another victim. The power supply was dead and so was the motherboard, as I discovered when I tried a Australia’s electronics magazine known-good power supply in place of the old one. I’d been advising these guys since they became my client to get a UPS (uninterruptible power supply) but as everything had been fine – until now – they (like many others) assumed their office was the exception rather than the rule. At least the hard drive appeared to be OK, so no data had been lost. I called and told them the bad news; they’d need a new computer. I also talked them into a UPS. In the meantime, they could think about insurance claims, but I suggested that I’d better build a new box straight away to get them going. They were fine with this, so I proceeded to strip the old box down; we could at least reuse the case. As I pulled it apart, I noticed a PCI expansion card that had a parallel port-style plug on the riser. It certainly looked like a typical parallel port, and this is what their large office printer/ scanner/copier/fax had been connected to. As many modern motherboards don’t sport a parallel port, I assumed at the time that it was a simple expansion card to allow them to connect this large printer/copier. Replacing the motherboard, CPU and RAM was unremarkable and only took a few hours. I also replaced the hard drive; if the machine had gotten January 2020  63 a power spike bad enough to fry the motherboard, it could have done some subtle damage to the drive too. Copying their data back and regenerating the shares was easy; the problems started when I took the machine back and reconnected their printer. With the vast majority of printers, installing them is a breeze. As long as you know the make and model number, drivers and utilities that support the printer are usually downloadable from the manufacturer’s web site. But I couldn’t find any mention of this printer at all on their site, and Windows didn’t pick it up as it does with many other printers. When I pressed the business owner for details on the printer, he informed me that it was a leased machine and not to worry too much about it as they’d get a technician from the lease company to come out to re-install it. Frankly, this was a relief, as I was out of ideas as to how to get this thing working. I tidied up the rest of what I could and they were back up and running that afternoon, bar the printer. As the manufacturer is one of the biggest names in printers, scanners, cameras and other consumer electronics, I had no doubt their guy would have the car yard up and selling old clunkers to the unsuspecting public before too long. The plot starts to curdle And that’s where things stood until the following morning, when I got another call from the car yard. Apparently, there was a problem with me messing with the printer, and the technician was getting all prickly about it and berating the owner, threatening all manner of ramifications. Technically, the car yard leased the printer; it was owned by the manufacturer, and the lease agreement states that nobody can touch the printer but the company’s representatives. That’s all fine, but apparently (and unbeknownst to me), they considered the expansion card to be part of the printer! This put the car yard owner in breach of his lease terms, and the manufacturer’s reps were now throwing shade on both of us because of it. I advised the owner that if he’d told me that the machine was leased, I wouldn’t have touched the thing with a barge pole, yet he didn’t, so I did. 64 Silicon Chip As I hadn’t yet been paid for the job, this caused me some stress, as did the vague threats made via the car yard owner from the printer people about my legal liability. That day certainly turned out very differently than I thought it would! And things just kept getting better; that afternoon, with the lease technician spending hours on-site trying to get the printer going with no luck, the car yard owner again called to tell me that the technician had taken the expansion card out of the machine and had supposedly found it physically damaged. Apparently, this explained why the printer wasn’t working. As I had been the one to swap it out, they reckoned that I must have caused the damage, and therefore was liable for both the card and any time this other guy spent trying to get it going. I’ve installed more expansion cards than most blokes have had meat pies, so I thought it very unlikely that I’d done any damage to it, especially without realising it. When I asked what sort of damage they found, I was told that there was an obvious mark on it, where it looked like a screwdriver had slipped and had gouged a track on the board. According to the tech, this was why the card wasn’t working and the printer not operational. I certainly don’t remember doing anything of the sort. When I asked how much the card was to replace I almost fell over; they quoted $4,500, and reckoned I was fortunate as this would be for a second-hand card; new ones were double that price! It turns out the printer was a deprecated model, and new cards were Australia’s electronics magazine no longer available. Also, as this one was the only card left and had to be imported from Australia, I would be liable for freight charges, a temporary printer rental for the time it would take to get the card as well as the technician’s fees to install it. All this certainly got me riled up; for a start, how could a PCI parallel port expansion card possibly cost that much, no matter how special it is? It would be cheaper if it was made out of pure platinum! And I’m pretty sure I didn’t stab this one with a screwdriver; if it was damaged, how do I know it wasn’t the other guy taking it out who did it? I called the lease company and asked to be put in touch with someone who could clear this up. I ended up talking to the New Zealand manager and he was as toxic as they come, threatening me with legal action. Dealing with them was thoroughly unpleasant, and my feeling is they went out of their way to make things difficult. I felt like I needed a shower after hanging up the phone. I wasn’t about to roll over, so I asked to see the damaged card myself and to at least have the right of repair. A cut track isn’t insurmountable, and if I couldn’t fix it, perhaps I could find someone else to do it. I was confident the card could be totally rebuilt for way less than four-and-a-half large! They reluctantly agreed and told me I could pick it up from the car yard the following day. I arrived to find the staff passing it around the office, trying to spot the supposed damage. I couldn’t see anything on it either, no matter how closely I looked (and I looked very closely!). siliconchip.com.au When I mentioned potential damage due to static, the yard owner commented that a courier had delivered it just as it was. There was no packaging, static or otherwise, with just a courier sticker protecting it. At this point, I realised that repair was not going to be feasible, and was reasonably sure the lease company had deliberately sent it like this. When I raised this point with them later, they confirmed it by stating that after talking with their legal team (!) the card was considered unserviceable as soon as I’d removed it and as such, they wouldn’t accept a repaired card anyway. They threatened to recover the money from me or the car yard, as we had jointly violated the terms of their lease. Nice people, and I’ll certainly never buy one of their products, no matter how good they are supposed to be. The owner goes to bat for me When all seemed lost, I found an ally in the car yard owner. He was more than happy with my service record and was appalled at how he and I were being treated and bullied by these people. After wading through the original documentation for the printer lease, he discovered that under the terms of the contract, the printer should have been regularly upgraded. Their printer had been due for that upgrade almost 18 months before all this happened. The leasing company had neglected to do this, essentially dumping this older model on the car yard. When the owner confronted them with this information, they immediately started back-pedalling and apologising and offered to install the very latest machine with free upgrades and anything else they could chuck in to sweeten the deal. The yard owner also stipulated that they also drop any claims against me and this they did, claiming that they had been talking about it and had already decided to upgrade the printer due to the cost and hassles of getting that second-hand PCI card for such an old machine. While that part still didn’t ring true, I was past caring and was hugely relieved. That sort of money is a major deal to a micro-business like mine, and I didn’t appreciate all the drama associated with it either. 66 Silicon Chip While all this was all going down, I’d spent much of my time panicking, studying points of law and even discussing it with a lawyer friend of mine, who fortunately hates corporate bullying and was happy to offer his advice for nothing. If push came to shove, I might well have been liable for those costs, especially if the lease company and car yard had both turned their guns on me; even though I’d only done as instructed, and had no way of knowing that I was doing anything wrong. Thankfully it all worked out, but you can be sure that these days, I check the lease status of similar hardware before I got anywhere near it. Sony 8FC-100 flip-card clock radio repair J. W., of Hillarys, WA is a regular contributor to Serviceman’s Log. This time, he repaired a clock radio which is as much electro-mechanical as it is electronic… A friend rang and asked if I could have a look at his broken clock radio. I told him that I would see what I could do. When he dropped it off, I was a bit nonplussed as it was much older than I thought. It’s the type of mechanical clock which has the numbers on cards which flip over under the control of a synchronous motor and set of gears, using the mains frequency as a time reference. I looked up the model number on the ‘net and found a service manual printed in 1972, so the clock is about 45 years old. I took it out to the workshop and powered it up. The radio worked, but the clock did nothing. So I took off the back cover and found that the radio module was behind the clock section, so I would have to remove the radio Australia’s electronics magazine to get to the clock mechanics. The radio PCB had several wires soldered to different tracks. I took a photo in case one or more broke off during the repair process. With the radio removed, I took out a few more screws and removed the clock module entirely. I could see a small motor with the rotor visible through a section of the case that was cut out. The rotor had some green and white tape stuck on it, so when the motor was spinning, it would be visible through the front cover as an indication that it was running. I tried to turn the rotor by hand; it moved, but a small piece of dried-up tape fell out. Maybe this was causing the low-power motor to stall. I plugged the clock back in, and the motor started to spin, with the clock now functioning. Even though some of the tape had fallen off, the rest still seemed to be stuck on well, so I decided to leave it alone, and not tempt fate by trying to dismantle the mechanism any further. The time and alarm are set using concentric shafts that protrude through the case. These connect to a system of gears. A microswitch riding on an adjustable cam activates the alarm, so that it triggers at the correct time. It’s quite a complicated mechanical device when compared to the all-electronic models that followed in later years. I put everything back together in reverse order, although it was difficult to determine the exact placement as the radio PCB obscured the clock module when trying to get them both back in the case. After some frustration, I had it all back together and powered it up as a final check. To my disappointment, the radio no longer worked. So off with the rear panel again. I siliconchip.com.au eventually found a black wire which had broken off the PCB; it was lucky that I had taken that photo earlier so I knew where to solder it back on again. Now it all worked well, and after leaving it running for a few days, I returned it to my friend. In fact, it belonged to his wife, and she was happy to have her ‘antique’ clock running again. Daikin Air Conditioner repair M. B., of Parramatta, NSW made two discoveries when his aircon failed. Firstly, sometimes you have to fix something yourself when even the experts give up, and secondly, parts may test OK, but they can still be faulty. Here is the story of how he tracked down and fixed the fault... A couple of weeks ago, thankfully as the weather was starting to get a bit cooler, my wife pointed out that our air conditioner was pumping out room temperature air. I repair cancer treatment machines for a crust and am reasonably confident about my abilities to fix most things around the home, but I’ve never tackled an air conditioner. So I rang the company who had installed it. The serviceman duly turned up, checked the refrigerant levels and found they were OK. After removing the top cover of the outdoor unit, he found that several error LEDs were lit. He said that given the age of the unit, it was unlikely that replacement PCBs were still available, and if they were, would probably be very expensive and possibly close to the cost of a new unit. I wasn’t surprised to hear this, so I asked the serviceman to get back to me about a quote for a replacement and got on with my day. After a few days, I hadn’t heard back from them, so I decided to check eBay for replacement boards. All three PCBs (Controller, Active Module and Power Filter) were still available and at a reasonable price, nowhere near the $3000 that a replacement unit would cost. I found to my surprise that I could get the boards directly from Daikin at roughly the same price as those listed on eBay. They would even take the boards back that I didn’t use and didn’t charge a restocking fee, which was a pleasant surprise. So I decided to try my hand at becoming an air conditioner mechanic. I bought all three from Daikin’s Warsiliconchip.com.au wick Farm (Sydney) warehouse for a total of $640. I wasn’t sure which PCB I needed; I would simply return the others once I’d figured that out. I was pleasantly surprised to find a free installation manual via a Google search. YouTube also had a couple of repair videos that, while not covering my exact symptoms, were at least for my specific model and gave me a bit more familiarity with it. So, emboldened, I lifted the lid and started to investigate. The YouTube video mainly talked about the boards failing due to corrosion. Even though these boards are covered by a protective lacquer, 10 years exposed to the elements would no doubt test it. My controller PCB didn’t look too bad compared to the ones in the videos, but was still covered in insect debris and dirt, and the lacquer was starting to perish in parts. The other two PCBs didn’t look too bad, so I dusted them down and removed the controller PCB to give it a thorough clean. I reinstalled it, crossed my fingers and powered it back on. It still didn’t work. I eventually figured out what all three boards do. The Controller PCB hosts the microcontroller, IGBTs and bridge rectifier. The “Active Module” is a Mosfet-based Power Factor Correction (PFC) device with an external inductor. The Filter PCB filters the incoming mains and the PFC-corrected DC output of the Active Module. There are five LEDs on the Power Filter board, one green and four red. The green LED is a ‘heartbeat’ to indicate that the microcontroller is active while the other four show error codes. Since the heartbeat LED was flashing, I suspected that the controller PCB was OK. The first two error LEDs were flashing, and according to the manual, this meant that one of the three thermistors on the aircon was faulty. The manual gave a method to test the three thermistors, which attach to the controller board via a single plug. It even gave a graph of the resistance vs temperature for these thermistors. So, armed with three glasses of water of various temperatures and a temperature probe connected to my multimeter, I checked all three thermistors on the loom. Removing the loom wasn’t too difficult. After plotting each, it seemed that they were all Australia’s electronics magazine January 2020  67 within cooee of what I’d expect, judging by the graph. I was still sure that most of the controller PCB was working, but now had some doubt about the thermistor interface. The part of the PCB dealing with the thermistors could be faulty. But not having new thermistors to hand, no proper circuit diagram, and since they tested OK, I decided to bite the bullet and swap in a new controller board. This was relatively easy. The only tricky part was needing to apply some thermal paste to the bridge rectifier and IGBT module heatsinks. So, with bated breath, I switched the circuit breaker back on. Nothing! Well not exactly nothing; the indoor unit ran for a couple of minutes before the whole thing shut down again. I checked the error LEDs again, and they were flashing in an identical pattern to before. After thoroughly reading the manual again, I discovered that in the indoor unit remote control could give more detail as to the cause of the fault. It indicated that the faulty thermistor was on the outdoor unit heat exchanger. This checks the temperature of the outdoor radiator. I was still puzzled by this, as all the thermistors had tested OK. I hadn’t purchased the thermistors on my first trip to Warwick Farm, as I couldn’t think of any reason why they would go bad. So I headed down to Warwick Farm again, to return the Active Module and the Power Filter PCB, and to pick up a thermistor set. To get to the condenser thermistor, most of the panels had to be taken off. I took plenty of photos to make sure I could put everything back together in the right place. But when I went to turn the unit back on again, it wouldn’t start at all! I thought I must have messed up when I re-connected the mains wiring. Thankfully, the manual has a diagram of the mains connection, and I discovered that I’d swapped the incoming and outgoing wires because the 1.5mm cable to the indoor unit and the incoming 2.5mm gauge wiring looked much the same in my photos. Anyway, having fixed that, I crossed my fingers and powered it up. The A/C fired up straight away, with no error LEDs lid, and cool air came out of the indoor unit! Success! I’m still puzzled as to how the thermistors had become faulty and why 68 Silicon Chip they passed my tests but were still bad enough to cause a controller fault. This is something I have not come across before in my field. I would like to know how the microcontroller determines that a thermistor is faulty. It must expect a very specific change in resistance during the start-up procedure. I ended up spending a total of $550, which is a lot less than a new aircon unit would have cost. I might be able to get some of that back by selling my still-working original controller board on eBay. USB flash drive repair D. M., of Toorak, Vic had some pictures on a faulty USB drive that he didn’t want to lose. It’s often (but not always) possible to recover files from flash drives. Luckily, he was able to do it... I had an old USB flash drive that stopped working about ten years ago. It contained some pictures I wanted to keep, but which I never backed up. This flash drive is a folding type; I did some research and discovered that these often fail due to broken internal wiring, which means it should be fixable. So I kept the drive, hoping that one day I could recover the data. To start the recovery process, I first had to carefully remove the plastic housing without damaging the enclosed circuit board. I used a ‘spudger’ tool which is like a plastic screwdriver with a wide wedge, to separate closely joined surfaces that are pressure-fitted or adhered together. Having exposed the circuit board, I established with a multimeter that the drive had failed due to a break in the flexible circuit board that formed the fold-out connector. So I had to join a new set of wires directly to the circuit board to bypass the damage. To do this, I had to work out which PCB pads were the connections GND, Vcc, D+ and D-. Getting GND and Vcc mixed up would likely be fatal to the device, but if you get D+ and D− swapped, it will typically still be detected as a USB device, but it will not work. The usual colouring scheme for USB 1.1 or 2 is GND (black or blue), Vcc or +5V (red or orange), D+ (green) and D(white or gold). Note that the device was a four-wire USB 1.1/2 device, not USB 3 which uses more wires. There is usually no indication on the circuit board as to which pin is which, so refAustralia’s electronics magazine The circuit board of the recovered USB drive. The connector with the defective flexible circuit board has been held down with tape to expose the solder pads, so that wires can be soldered to them for data recovery. erence needs to be made to the original connector. To make the connection, I cut an old USB cable in half and kept the end with the Type-A plug. I then stripped the four exposed wires and soldered them to the pads on the memory stick circuit board, after having determined, based on the original cable, which end was GND. I first tried an old drive for practice soldering the very small wires. I then moved onto the recovery target. Once the wires were soldered correctly, I connected the drive to a computer. It detected a USB device, but I could not access it, so I swapped the D+ and D- wires. I then plugged it back in, and it worked immediately, so I copied its contents to the computer. I was delighted to have gotten my photos back. The pinout of a USB Type-A connector. The white area (top) is the cavity while the dark area (bottom) is solid material. Pin 1 is Vcc or +5V, 2 is D-, 3 is D+ and 4 is GND. Doublecheck and triple-check that you get the corrections right, referring to the old connector, as it may be hard to figure out the connections from the SC circuit board alone. siliconchip.com.au