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SERVICEMAN'S LOG Why can't I program MY alarm? Dave Thompson* Many moons ago, I wrote about an alarm system I was having trouble with at my then residence. I’d experienced intermittent problems with it in the final few months of its almost tenyear lifetime and it had finally given up the ghost, which was a real shame as it had been such a good system. Items Covered This Month • • • Bosch burglar alarm Marantz SR870 receiver repair Mitsubishi air conditioner *Dave Thompson runs PC Anytime in Christchurch, NZ. Website: www.pcanytime.co.nz Email: dave<at>pcanytime.co.nz It had protected, without fault, a couple of our dwellings with attached workshops and had been disassembled and re-installed several times as we’d moved from place to place in the early days. The problem with all electronic hardware is that it is usually quickly superseded and this alarm system was no exception. Of course, the alarm company who’d originally installed it was more than happy to pull it all out and replace it with a shiny new version, with more bells and whistles but apparently that also meant changing all the sensors I’d spent a considerable amount of time and money on. The sales guy was adamant they were no longer compatible with newer systems, a statement I viewed with great suspicion. I was subsequently vindicated when I learned that all my sensors would have worked with any new panel sourced from this company (and probably dozens of others as well). 40 Silicon Chip However, that deception aside, I was not yet in a position to shell out the amount of money they wanted for a new system, especially as they’d “given” us the old system as part of a deal when we signed up to a monitoring contract with an affiliated security company. Back then, we got the basic system (which came with three standard PIR sensors and a smoke alarm) if we agreed to a two-year monitoring deal, which was actually a win for both parties. We got a good quality, monitored alarm system and they got a dollar a day from us for a couple of years, guaranteed. From what the installers said as they put the thing in, they had "sold" a huge number of these package deals and were run off their feet with installation work. Unfortunately, now many years down the track, that deal – or any others like it – no longer exist, which is why I baulked at the quoted cost of a new system. Celebrating 30 Years Before making any decisions, I looked at all the alternatives. I wouldn’t be much of a serviceman if I neglected to do my due diligence! The system we’d been using, the Solution 6 + 6, was made by Bosch, a company not known for making junk. So although it was basic and essentially given away as a deal sweetener, it was by no means a bottom-of-theline system. We’d also added a whole bunch of extra sensors to the "free" package, as we also wanted to include our garage and workshop, an altogether much larger area than the standard package was designed to cover. Thus, we ended up with an array of door and window switches, extra smoke alarms and more PIR sensors, with pet-safe versions of these detectors replacing the standard versions that came with the package deal – all at our expense, of course. Overall, this system was rocksolid. I can only recall one instance of siliconchip.com.au it going off with no apparent cause, the dreaded false alarm. Fortunately, it was in the middle of the day and I was nearby, so no real harm was done. Even though I knew which zone and sensor was responsible, I never did figure out why it went off and as it never happened again, I didn’t lose too much sleep over it. Newer isn't always better In contrast to this, I have lost count of the number of times the much newer and far more sophisticated digital alarm system (purchased from AliExpress) at our new place has gone off over the last 18 months with no apparent trigger. Like any electronic device, the more complex it is, the more likely that it will give problems. No doubt there is a law named after some famous academic used to describe this phenomenon, but as I’m not aware of it yet I’ll take a punt and call it "the Serviceman’s Law". This new alarm system does have several advantages over that old one though. We now have features such as wired/wireless sensor connections, manual/keypad operation, RFID or key-fob arm/disarm and both GSM and copper-line connectivity for monitoring. If required, I could use up to 99 sensors with the new system, while I siliconchip.com.au could wire in a maximum of only 12 with the old one (and even then, I’d have to use some jiggery-pokery to achieve that). Still, that old system was highspec in its day, and as I said, it hardly missed a beat until a few months before it died. As I wanted to keep using it at the time, I’d needed to come up with an alternative to total replacement, and that meant finding a new main board, or perhaps a whole new alarm panel, which was a tough ask considering the age of it. As it turned out, I got very lucky. On a local auction site, I found a guy selling a brand-new panel and a new, spare keypad for my exact system. He’d somehow ended up with two panels and an extra keypad for a job he was doing (I didn’t ask) and now, a while after the fact, he was cleaning out his garage and wanted to be rid of it. I was happy to part with a hundred bucks for the panel and keypad, which was a bargain considering what the alarm company wanted for that new system. The new panel included the steel mounting box and power supply board. All I had to do was disconnect and remove the old box and then connect and mount the new one using the same screw holes. It was an easy task; I didn’t require any diagrams or circuits as I just swapped out sensor wires and resistors from where they were connected on the old board to the corresponding terminals on the new panel. The most difficult and time-consuming part of the whole process was programming the new board with all our settings. This process also raised an interesting philosophical issue. The new main board had been pre-programmed by the alarm company who’d imported it using their own unique installer code, which meant that I could not fully program the alarm board as I didn’t know the code; the seller didn’t know it either. There are two codes used in this system, both of which have their own levels of access to the system and its various functions. The installer code is used to program all the non-consumer related information into the panel, such as telephone numbers for remote monitoring, different options for the various types of sensors, zone Celebrating 30 Years settings and other miscellaneous technical parameters. Importantly, the alarm cannot be armed or disarmed using the installer code, a necessary safeguard to help prevent rogue installers going around disabling alarm systems. That said, installers can add "master" codes, which are used to disarm systems, and they usually do so as a service to the customer, mainly because most new alarm owners do not have the desire to go poking into the workings of the alarm system, nor do they want to have to wade through the manual in order to learn how to program in their own codes. Those who are prepared to read the instructions, or who are concerned about others (namely the installers) knowing their alarm codes are able to create their own master codes, although this is about the only thing they can do without requiring the installer codes as well. The main problem is that, for obvious reasons, the installer codes are almost never released by the alarm companies. This raises the philosophical issue I speak of; while it is fair enough for installers to retain those codes if they (or their affiliated monitoring company) have installed a "free" alarm system along with a monitoring deal, I bought and paid for this particular panel outright, so surely I should be privy to any and all codes and keys used in the system. Not knowing that installer code, severely limits what I can do with it, and this is just not cricket. This would be akin to me putting a BIOS or set-up password on every computer I sold and then charging a fee to anyone who wanted to get into the BIOS to, for example, add another hard disk or alter existing settings. April 2018  41 To any right-thinking person, this is not acceptable, and yet as far as I can tell this is industry practice in the alarm business. There is a potential “back door” though; the main logic board has a "set default" button on it, which does exactly what you’d think it does, and that is re-set any programmed settings back to their factory defaults, including the installer code and master codes. This action can also be accomplished using certain codes sent to the logic board via any of the alarm keypads. However, as always, there’s a gotcha involved. There is an installer option to protect that setting and this prevents the set default button or keypad codes from being used to default the system settings. While the service/installer manual specifically advises against using this setting, as it requires the unit to be sent back to an authorised agent for reprogramming (or in this case, requires me to pay some guy to come out and do it), this particular company chose to ignore the instruction manual and set that option to on, preventing me from using it to default the settings. Nice one. I understand there are business and security implications to this, however, any bad guy would have to be pretty clued up in order to go around accessing alarm systems and besides, it would be a pretty obvious clue if the alarm was disabled by someone other than the owner. Either way, in my opinion, setting an installer code and making it non-removable is not warranted, period. In the end, I had to pay a couple of likely lads to come out and remove that installer code. They didn’t want to do it, and certainly wouldn’t tell me what the code was – not that it mattered; I neither needed nor wanted to know it, I just wanted it defaulted – but it turned out that they didn’t actually know it anyway. However, I put my case in strong terms that this was now my alarm and as such, they or their colleagues had no right to set any passwords or codes into it that prevented me from accessing any settings within it. After a lot of back and forth and a few phone calls to superiors and other installers, they agreed to default the panel, trying all the codes they knew, including those used both past and present, to default it. They eventually chanced upon it setting everything to default. Commenting that this code had not been used for many years, they eventually loosened up and showed me around the programming side of things and even demonstrated how to use a programmer board to make things easier, and double-checked the option that prevented the defaults from being set was disabled. In the end, we recognised we were all servicemen and as such were kindred spirits. They knew I wouldn’t be going around busting open alarm systems and were happy to share those few tricks of their trade. I’ve engaged them several times since to do alarmrelated work and it is nice to have a connection to people with those specialist skills. Well, that's one way to stop it beeping I bring the subject of this alarm system up because last week the guy who’d been renting our old place (the one with the repaired system installed in it) moved out. When I went in to check the property out, I found he’d somehow disabled the alarm system; it was completely dead. When this bloke had first moved in, he’d mentioned that the alarm would be a welcome asset as he had some expensive laser-cutting equipment he wanted to set up in my old workshop. Obviously, something had changed in the meantime, so I got in touch to determine why the alarm was no longer working. He claimed that shortly after he moved in, it started displaying a "mains" error on the keypads and because of this, the system beeped once Servicing Stories Wanted 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. 42 Silicon Chip Celebrating 30 Years a minute, which it is designed to do. Not knowing better, he’d climbed up to where the main alarm panel is located, opened the box and disconnected the mains connections and battery terminals, thus shutting the whole thing down and killing the beep. If he had called me, I could have told him how to stop that beeping in five seconds with the push of a keypad button. However, he fancied himself a bit of a DIYer and preferred to resolve it himself in his own refreshingly nontechnical way. I empathised though; that beep is annoying. Every keypad has a piezo buzzer, so any warnings are audibly announced, along with flashing zone LEDs, and in this case, the warning would go on either until mains power was restored or the battery went flat (or someone physically unplugged it!). During the quakes, we lost power a lot, so I am intimately familiar with that particular warning. Still, his response was a little heavy-handed, and as it turns out, there were a few other "command" decisions he’d made that he wasn’t entitled to make as a tenant; the alarm is just one example. The first thing I had to do was dig out the alarm’s service manual again. With no power for over a year, I might need to re-program it. I made my way into the roof space and found the panel door wide open and full of new residents. A quick vacuum cleaned it all out and I could then see he had simply cut the wiring. Again, if he’d called I could have told him where the master switch was at ground level. None-the-less I reconnected it all, but when I flicked the mains switch on, there was nothing, though when I re-connected the battery leads, I heard a beep and the keypads lit up with fault indicators. At least the battery was holding its charge; fortunately, I’d replaced it not long before we moved out so it was still fairly new. However, the problem was still no mains power. I broke out my line testing tools and worked backwards from the panel through the system until I discovered that the mains feed to the panel was dead because this guy had wired in an extractor fan for his laser and had inadvertently killed the alarm circuit, which caused the mains fault. He’d removed and taken the fan away, so I used a junction box to re-consiliconchip.com.au The Marantz receiver is tightly packed with components, making testing difficult. nect the loose cables and with power restored, the beeping stopped and the fault cleared. All my settings had been saved, but I changed all the codes anyway, just to be safe. Who knows, there may be servicemen around who are not as trustworthy as I am! Marantz SR870 receiver repair R. A., of Melbourne, Vic, recently fixed his venerable Marantz SR870 Home Theatre Receiver. It has given nearly 20 years of sterling service and will now likely soldier on for another 20. The fault he discovered was all too common and luckily, easily fixed. Here’s his story... While studying to be an engineer, I worked as a serviceman and have dabbled in servicing ever since. Like all servicemen, my own gear is the last to be fixed. My 19-year-old Marantz SR870 5.1 channel home theatre receiver had been playing up for well over a year. Every now and then, it would spontaneously power down then usually quickly reset, sometimes repeating the cycle then usually settling down. Recently it played up more frequently and now would sometimes not recover at all for quite some time. Eventually, I decided to do something about it. My initial thoughts were to suspect a capacitor in the power supply or maybe even a faulty fuse. After removing the receiver from its place in the system (no trivial task and the reason for the procrastination), I pulled the cover off and inspected the power supply board. Everything looked fine. No bulging capacitors, the fuses looked rock solid and were a quality type. The fault was siliconchip.com.au so intermittent that waiting for it to fail on the test bench was an exercise in frustration. It was clear to me that all mains power was being lost when it did fail, so I did the easy thing and replaced the mains cord, which had some very sharp bends in it where it was clamped in several places. Back in use, it worked well for about 24 hours – then failed again. The receiver was packed full of components (as shown by the photo above), had been well built and was in excellent condition, so I was loath to start pulling out components on a search-and-destroy mission. Even measuring voltages was impossible on some of those nested PCBs. Instead, I looked on the internet for clues but there was little information available. However, I came upon a YouTube clip where an American technician worked on a similar receiver. The interesting thing was that there were lots of comments below the video, none of which related to the video but were asking all sorts of questions regarding receivers and faults. The small power input PCB from the receiver. Celebrating 30 Years The technician replied to all comments with patience and much insight. So, I took a chance and asked about my SR870. Overnight he replied, saying that there was a common problem due to poor soldering on the power input PCB. In particular, he said to check the soldered joints on the small standby transformer and regulator IC. I retrieved the unit and opened it up again, then removed the PCB in question (shown in the previous photo). It was relatively easy to get the PCB out; I just needed to remove the big main transformer to give some wriggle room and also work out how to unclip each small connector. Only two of the five used the same locking tab arrangement. Using reading glasses with three times magnification, I discovered that at least one soldered pin on the primary of the transformer looked dodgy. So I took macro photos and then re-soldered every transformer pin and every pin on the aforementioned IC and put everything back together. Cutting to the chase, this completely fixed the fault. Later, looking at the photos on a large monitor, it was obvious that all three of the primary pins of the transformer, along one side, had faulty soldered joints (see the photograph below). All the other joints looked OK. My theory is that a flawed mechanical design caused this issue. The manufacturing process required the transformer to be first soldered to the PCB, then two long self-tapping screws went through lugs on the transformer, through the PCB, through a standoff, to the chassis. Tightening these screws forced the transformer into the PCB and thus placed strain on the solder joints. I was happy to have given the receiver another lease on life. Reflecting on it later, you might think that a receiver that old should be replaced by a newer “better” unit. In fact, it was already superseded when I bought it new (at a good price) in 1998 as it only had Pro Logic decoding, not Dolby Digital or DTS. April 2018  43 However, it has an analog 6-channel direct input to cater for then-future decoders, so I have used it continuously with a variety of DVD players with 6-channel outputs, plus PVRs and other boxes over the years. Hence, the amp is future proof, which fits my philosophy of also buying the dumbest TV and using it with an external set-top box (with built-in media server/PVR/Fetch box/etc). It’s much cheaper to replace a box when technology advances than replace the amplifier or large screen. The introduction of H.264 compression is one example where this philosophy pays off. Also, I reflected on the good electronic design that utilised 1000+ electronic components that still work perfectly 20 years after manufacture, 25+ years after it was designed. Would today’s replacement actually be “better”? Researching possible new replacement units, a popular brand has a 7-channel, 115W/channel (single channel driven rating), and weighs just over 8kg, retailing at about $1000. The old Marantz weighs 14.4kg, most of it being the power transformer. Rated at 110W/channel (two channels driven), its multi-channel performance would easily eclipse the new unit due to the much beefier power supply. So I am glad to have given the old Marantz a new lease on life. I also still have the original RC2000 remote control – the “Remote of the Gods” – but that is a story for another time. Mitsubishi air conditioner repair J. N., of Mt Maunganui, New Zealand, recently faced a common problem with his home air conditioner; spare parts were becoming so expensive and difficult to get that it looked like it might be cheaper to replace the whole thing than repair one small fault. Luckily, he managed to get it going again anyway... As a semi-retired electrical/electronics technician, I like to do any servicing or repairs on our home appliances myself. The one time that I decided not to, it ended up with me finishing the task anyway! About a year ago, we had an extra Mitsubishi heat pump installed in our house, adding to our existing old but faithful Mitsubishi MCFH-A18WV. I usually service the old unit myself but we decided to have both units serviced by the installer of the new unit before winter set in. They arrived and proceeded to service both units and found that the old MCFH-A18WV would turn off OK but the internal fan kept running. According to the service engineer, the problem was in the main Electronic Control (EC) PCB and it would have to be replaced. I requested that they give me quote for the supply and installation of this unit. His estimate was around $300-500 for the part plus labour, which made me flinch! I asked him to please check this out with a firm quotation. A couple of days later, the company came back with very pleasant news indeed. It appeared that because our old unit was so outdated that there was only one PCB in stock in the whole of New Zealand and the agents were prepared to let us have it for only $32.90 including GST! Well, of course, we agreed. Several days later, our service engineer turned up and duly replaced the Electronic Control PCB, only to find that now the internal fan motor did not work at all! After a lot of testing, he now announced that the fan motor had burnt out one of its windings and also that the main EC PCB was probably corrupted and would have to be replaced again! By this time, I was beginning to think that we should bite the bullet and replace the whole unit. It was agreed to get a further quote from Australia for parts alone, ie, the fan motor and a new EC PCB. In the meantime, I decided that it would not do any harm for me to investigate myself. I was able to download the circuit diagrams and went about conducting my own tests. All seemed well until I came to check the fan motor stator windings which involved one main winding and four separate coils, providing different fan speeds. Sure enough, the main stator winding showed an open circuit on my ohmmeter. This did not make sense until I re-checked a separate circuit diagram which showed in very small detail that this winding was protected by a fuse. Where was the fuse, as none was in sight? The penny dropped; it was embedded in the windings and was obviously a thermal fuse. I simply bypassed this fuse by temporarily altering the wiring and the retested the winding to find that it read the required 79-97W. At switch-on, the unit operated as it should, so the new EC PCB was not faulty. True to their word, I received a phone call from the servicing company to inform me that a new fan motor and EC PCB would cost over $1000 plus labour and GST. I am not sure what they thought when I informed them that the unit was working fine and we would not need the new parts. Since then, I have removed the fan motor and installed a new thermal fuse as best as I can, to protect the motor, and I am still going to attempt a repair one day on the old EC PCB which had been previously removed. In the meantime, our good old heat pump is still SC chugging along. Are Your S ILICON C HIP Issues Getting Dog-Eared? 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