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SERVICEMAN'S LOG A laptop, spilled tea and a crack The vast majority of my ‘bread-and-butter’ work is mundane to the point of being drop-dead boring. Most of it wouldn’t even pass muster as a footnote to more interesting stories. If I wrote a column solely about these jobs, you’d probably unsubscribe in disgust. However, occasionally a job will come along that is worth mentioning. One such job that comes to mind is something I tackled a little while ago. A customer brought in a laptop that wouldn’t boot. It had been working well until recently; I’d given it a thorough service about six months ago. But while cleaning a shelf above the computer desk, the owner had dislodged a decorative, over-sized tea mug and this had fallen onto the laptop, landing square in the middle of the keyboard. The machine wasn’t running at the time, but when she tried to power it up after the event, the lights were on but nobody was home. She called and asked for advice, and my recommendation was that she bring it in so I could assess it, see what’s going on and then we could go from there. It seems to be the way things often work out that the customer was in the middle of an assignment that was due in a few weeks and her main concern was losing her data. I told her on the phone that while it was very likely her data was intact, I wouldn’t know for sure until I got my hands on the machine. The fact the laptop wasn’t running at the time, and the likelihood of the hard disk being mounted some distance away from ground zero, meant that it would probably be OK. When I opened the lid, the first thing I noticed was a slight bulge in the centre of the keyboard, which she confirmed was the area of impact. While barely perceptible, it was readily apparent in the right light. That sort of thing never bodes well, given the lack of room available in most laptops; something must have given way under there. siliconchip.com.au I whipped the back plate off and removed the hard disk, which I then plugged into a workshop computer using a USB-to-SATA bridge adapter. I ascertained that her data was still where it should be and informed her that while I’d need to run a few tests over the drive, the fact it spooled up and could be trawled without complaint meant I could be reasonably sure it would be all right. Dave Thompson Items Covered This Month • • • Repairing a beaten laptop Cleaning PC motherboards Philips air fryer repair *Dave Thompson runs PC Anytime in Christchurch, NZ. Website: www.pcanytime.co.nz Email: dave<at>pcanytime.co.nz A stern lesson on backups The customer was understandably relieved to hear this good news, and I took the opportunity to give her my standard backing-up pep talk. Like most people, she had a Australia’s electronics magazine April 2019  53 backup system installed and set up, but after the first initial backups done many months ago, she just never got around to running it again. Given that people’s data can change radically within days, a regular backup is never a waste of time. While a lot of today’s technology users rely on the “cloud” retaining backups of all their data, many have no idea where that data actually is or even how to go about retrieving it should disaster strike. They’ve either been told that once they set up their phone or computer that all their data will automatically be backed up to a cloud account, or they’ve misunderstood what backing up to the cloud really entails. Easily-overlooked details such as needing to have an active iCloud, OneDrive, Google Drive or similar account in place and the fact there is often a need to actively manage the files that are supposed to be backed up to remote locations leaves users vulnerable to data loss. It is also worth remembering that in the past, services such as Google, Amazon and Yahoo have lost vast swathes of users’ data with no recovery or compensation. Users with years of email history, documents, photos and other irreplaceable files had to write it all off and start over from scratch. That’s a tough pill for anyone to swallow, yet these sites offer precious little information on how to go about backing up that cloud data, requiring end users to deal with it instead. Editor’s note: if you use Google services and are concerned about this, check out http://takeout.google.com which allows you to download most of your data hosted by Google, easily. I’m not saying don’t use such services – I make good use of the OneDrive system that comes with later versions of Windows. I’m just saying that these companies typically encourage endusers to forgo local data storage and hard-copies in favour of using their all-singing/all-dancing online services. Many users aren’t even aware that these services can fail, so it is essen- tial that backups are made and kept up-to-date. If that isn’t bad enough, many new customers of mine are horrified to discover they are not backing up what they thought they were backing up. I’ve seen plenty of external drive ‘backups’ with only desktop icons, empty folders or thumbnail files instead of original photos copied over. I try to remedy these situations by installing and setting up a backup program that takes just three mouse-clicks to get up and running. However, while it can be scheduled to run automatically, there is usually still some manual input required, such as plugging in an external hard drive or flash drive on which to copy the backed-up data, and people being people, this is the point we usually forget or simply flag it, convincing ourselves it’ll be OK for one more day. If only I had a dollar for every time I heard that mentioned after a hard disk failure! We now resume our regular service(man) Back to the bulging laptop. I removed the screws holding the keyboard in place (typically hidden under panels around the back of the machine) and carefully released the retaining clips to prise the keyboard out. Surprisingly, no keys had broken or popped off, some- Getting to the root cause Do you have any good servicing stories that you would like to share in The Serviceman column? If so, why not send those stories in to us? 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. The connector is similar to a PCB stacking connector, and a quick browse on the usual-suspects component sites revealed that they are available for only about five bucks. The problem is that while I could probably fluff about and fluke soldering one of these things on, getting the old one off without a lot of collateral damage would be a real mission. I know this because I have attempted Australia’s electronics magazine siliconchip.com.au Servicing Stories Wanted 54 thing that often happens when a heavy object is dropped on a laptop keyboard. Repairing those little cantilever plastic ‘springs’ under the keys is a royal pain, so thank goodness for small mercies. Underneath, I could see areas of the motherboard and the usual peripheral-connecting ribbons poking through open sections in the top frame. I could also see where the cup had impacted; there was a nice dent in the thin metal chassis. Beside that was a multi-pin plug that had popped off its socket; the plug’s leads disappeared off to the screen, so this explained the lack of video. It also explained the keyboard hump. This could be an easier fix than I thought; all I had to do was panelbeat the bent section of the case back into its original shape, plug that big connector back in and it should work. But you know it’s never going to be that easy! When I tried to replace the popped plug, it wouldn’t re-seat, and on closer inspection, I could see that the socket mounted on the motherboard was cracked right through, making each end kinked slightly offline and preventing the plug from going in. Excellent! Of all the places on this motherboard, the cup had to fall onto this point. Before going any further, I had to remove everything from the case so that I could straighten the bent chassis properly, and that entailed taking out the motherboard assembly. There was nothing special to it, just a lot of screwdriver time making sure all the screws were removed (even the one hidden under the hard disk and the three tiny ones along the edge hidden by the CD-ROM drive) before separating the clips holding the two halves of the case. I soon had the case bent back into shape, but I was more concerned about this 40-odd pin micro-socket with the crack in it. Silicon Chip stuff like this in the past, and at the risk of being labelled a man who blames his tools, I blame my lack of proper SMD desoldering tools – and the talent to make the best use of the ones I do have. If this was my motherboard, I’d likely have a go, but for a paying customer, I draw the line. Removing an 8-pin SMD is one thing, taking off a bonded 40-pin socket like this is another game entirely, especially when it is on a tightly-packed motherboard. So I thought I’d check it under a microscope before deciding what to do next. I could see that all the legs were still securely soldered and nothing was really out of place, except for the misalignment of the now-separated hard resin body of the socket. The crack went right through it, and if I pressed in the right places using some repurposed dental tools, I could close the crack right up and straighten the socket, likely enough to put the plug back onto it. But as soon as I released the pressure on it, it would open up again. I made a vague attempt to close the socket and while holding it closed, replace the plug with my third hand, but while it did close with a bit of pressure, it wouldn’t hold, and without some extra tweaking I knew this wasn’t going to fly. Back under the microscope, I could see the majority of the socket’s pins siliconchip.com.au were still straight, with only a couple on each side adjacent to the crack itself bent out of line. All the pins were holding the two halves of the socket tightly, if apart. I reckoned that if I could straighten those bent pins, this would relieve the stress holding the break open, and it would let me get some glue in there to close the crack. I would then just need to hold it long enough for the glue to cure, and in theory, I would be able to re-connect the plug and it “should” work. That’s a whole lot of “ifs” though… The biggest problem I faced is that one drop of glue in the wrong place and I’d be right in the litter box; the connector would never go back onto the socket and if it did, the chances are that one or more pins wouldn’t make proper contact. Considering the size of the component, and the consistency of most of the glues I have access to that could bond this type of resin with any strength, I would have trouble getting enough glue into the crack without spilling any over into the surrounding areas. I would also only get one shot with this method and if it didn’t work, it would be game over. After much wringing of hands and gnashing of teeth, I considered my only feasible option would be to juggle things enough so I could dry-fit the plug to the socket, make sure it Australia’s electronics magazine April 2019  55 worked and then spread glue over the entire plug and socket assembly so it couldn’t move. With this method, the elephant in the workshop is the trouble I would be in if it ever became necessary to get it apart again, ie, if something else should go wrong with the laptop. Once the plug was potted, it wouldn’t be coming off again and, due to the way the connected cable interacts with other removable parts of the laptop, that would make disassembling the machine again virtually impossible. I decided to put these issues to the client, who had already been half-resigned to getting a new machine anyway, given she thought this one was dead. I called her and told her what I’d found, and after discussing the options, she was happy for me to go ahead and try to repair this one, with the full knowledge that it might not work anyway, and even if it did our future repair options would be severely compromised. Repair time! With the go-ahead given, the first thing I did was straighten the pins out. While I have plenty of microtools for this kind of work, I always gravitate back to using my array of dentists’ tools. These picks, probes, burs and scalers are excellent for electronics work because they are strong, resilient to fluxes and solders and very hard. I use them for everything from mixing glue to cleaning circuit boards. Don’t be afraid to ask your dentist for old ones – they chuck theirs away regularly, usually regardless of condition because they get brittle with repeated sterilisation (among other things) and become a bit dangerous to use. My dentist has a carton of old tools and I never leave empty handed (it is also nice to get something, other than working teeth, for all that money dropped there!). The tools are usually cleaned in the autoclave before being disposed of anyway, so there are no worries about them being dirty. I had to promise my dentist that I wouldn’t use them on my or anyone else’s teeth, and surprisingly, that’s not a tough promise to keep! The extremely sharp probes that typically strike fear into the hearts (and mouths) of patients are ideal for this 56 Silicon Chip pin-straightening business. I used one to gently coerce the dodgy pins back into line. This worked better than I expected and all the pins were equally-spaced and still well-connected to the motherboard once I’d finished probing. The crack in the resin part of the socket now looked to be just a hairline and the plug fitted back onto the socket relatively securely. I assembled the laptop parts on the bench and sat the battery onto the motherboard’s battery connector. When I pushed the power button, the screen lit up and the machine tried to boot, but because I had no hard drive in it, I merely got the usual “no system disk” message. With that working, I removed the battery and other bits and tried the plug again; it was still too easy to disconnect. Usually, it is held quite firmly by friction, but now it wasn’t even holding stable with the plug pushed on as firmly as it would go. I taped it down, mixed up some epoxy resin and ‘tagged’ it with a good-sized blob at each corner. When set, the plug was held in so it wouldn’t come out, yet was accessible enough so that if I needed to remove it again, I could break the glue. I reassembled the laptop, and with everything attached, it booted into the operating system and worked as expected. The keyboard no longer had the hump, and there was still some wiggle-room should we need to get it apart Australia’s electronics magazine again. The owner was happy, I was happy this fix would last, and everybody wins. Sometimes it is worth having a go anyway, even if the outcome looks bleak. Cleaning motherboards B. W., of Warriewood, NSW lives near the coast, and a common problem with electronics (and especially computers) in these humid areas is corrosion and a build-up of dust and other gunk on the circuit boards. This eventually interferes with the operation enough to cause failures. The solution is to give them a good old clean and check them over for any other problems while you’re at it... I have five PCs making up a broadcast HD editing system. The oldest, a 2003 model with a Gigabyte motherboard and an 8-slot NAS with 16TB of storage has worked flawlessly for 12+ years, but recently it started getting slower and slower. Finally, it refused to switch off; then when I forced it off, it wouldn’t power back on. While all the power supply output voltages seemed OK, the motherboard lacked 12V in some locations. It was time to bite the bullet and pull out the motherboard. Living on the coast, many times over the years various bits of electronic gear have chucked a wobbly or just stopped and the reason is usually dust, fluff, hair and other fine debris that gets deposited on the PCBs, stuck down with a salt-laden conductive deposit from the sea breezes we often get. siliconchip.com.au Before and after cleaning the PC motherboard; note a few of the ICs had not been re-seated yet. With the narrow pin spacing of modern ICs, the worst thing you could organise is dumping a conductive matting over and between the tracks and the pins of the ICs and surface mount parts. Many bits of gear are thrown out just because they have been used in this environment for several years and then simply quit working. They usually wind up in the council cleanup. The simple cure is the get out the methylated spirits, some old toothbrushes, small art painting brushes, clean rags, old newspapers, magnifying glasses, a fine bladed scalpel, and ensure no ignition sources exist. Pour a small amount of metho into a lid or other container, and use the tools to wash/scrub down the PCB with all the sluiced-off waste going onto the newspaper. Use the scalpel and toothbrushes to very carefully clear between the fine pins of the ICs. Mop up any leftover metho with a tissue or a rag; you can even use a hair dryer to dry it off, ensuring that no metho hides under the ICs or other components. Re-assemble the equipment, and that’s it. While cleaning up this PC using the above method, I discovered a bloated 3300µF capacitor, so I replaced that too. Then pow, up it came first go, and I’m typing this tale on it. So before you throw any gear out, give it the big clean; you may be surprised just how well it works, and just how easy it is! to fix them but this raises the possibility that these designs are not rugged enough for our electrical grid... This problem may be of interest to your readers as it appears to be a common fault with Philips HR2940 Air Fryers. I have two units which were both dead, having no display. The first problem was removing the top cover to get to the power board. You need a long T20 screwdriver as the screws are deeply recessed. My photo shows the unit after the cover is removed, with the power supply board visible. The power supply board uses the ST Microelectronics Viper16 8-pin DIP flyback switching regulator IC. This has an internal high voltage (700V) FET which failed and destroyed the two 30W resistors feeding it. The fuse survived(!) It seems that these ICs are not able to handle the high voltages they can be exposed to. Replacement ICs are available from RS components. I also found that C6 (10µF 50 V) was shorted out on both Air Fryer power boards. Replacing the regulators, 30W resistors and 10µF capacitors got the units back up and running. Note that the power board will not produce any output unless it is connected to the control/display board. While I had the units open, I also added a metal oxide varistor (MOV; blue disc) across the 30W protection resistors at the IC’s high voltage inputs. It should reduce voltage spikes getting to the Viper16 IC. I am hoping that this will prevent similar failures in the future. There is a similar problem with some Toshiba TV power supply boards. These use a similar high voltage 8-pin DIP IC (ICE3B0365) for the 5V standby power supply. These are also made by ST Microelectronics. I have three boards where the same IC SC has failed. Philips air fryer repair R. S., of Fig Tree Pocket, Qld has multiple failed power supply boards exhibiting the same fault. He was able siliconchip.com.au Close-up of the power supply board used in the Philips HR2940 air fryer. The only IC (a Viper16) in the unit had failed due to high voltages. Australia’s electronics magazine April 2019  57