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SERVICEMAN'S LOG Repairing ‘proper’ stereo gear is satisfying Dave Thompson* I am sorry but I don't think much of a lot of modern consumer gear. It is not built to last and it generally is not worth trying to repair. Give me the ‘proper’ stuff made in Japan, America and Europe in those halcyon years between 1970 and 1990 – or thereabouts! For as long as I can remember, I’ve been either building or repairing electrical and electronic hardware and, in that time, I’ve encountered many kindred souls who share my views that in certain circumstances, older devices are superior to their modernday counterparts. This is fortunate for a serviceman, because these people are happy to spend money on repairs rather than simply splashing out on something new. While some may put this down to that time-honoured, generational phenomenon where we think that our first, 5-valve mantle or 7-transistor pocket radio sounded way better than any of this modern digital rubbish, and that this rose-tinted view is just nostalgia, I’m not too sure. Obviously, this theory doesn’t hold true with every device ever made – mobile phones and DVD-burners are two that immediately spring to mind – and it's clear that many other modern devices far outperform their older versions in almost every respect, but it doesn’t take much digging to find some good examples. Take hifi stereo amplifiers; robotically mass-produced, cheap, modern units often can’t hold a candle to their Items Covered This Month • Repairing a Pioneer SX-950 amplifier • Rohde & Schwarz spectrum and distortion analyser repairs *Dave Thompson runs PC Anytime in Christchurch, NZ. Website: www.pcanytime.co.nz Email: dave<at>pcanytime.co.nz 58 Silicon Chip 70s, 80s and some 90s hand-assembled counterparts. On paper, even the most basic modern amplifier out-performs older amps, but as any audio aficionado will tell you (often at great length), a system’s sound isn’t just about having an amplifier with an output of 750W RMS per channel, a THD figure of 0.00000001% and a signal-to-noise ratio of -1000dB. Don’t get me wrong; building or even designing an amp with those specs (although I might have exaggerated just a touch there) is a huge achievement and something that could only be possible using today’s technology, but I’ve seen too many expensive systems with specs that would make an audiophile’s heart flutter that sound terrible to my admittedly rock-and-roll pounded ears. Sound is so subjective; I once flatted with a guy who was also into music, and we shared my stereo sound system. No problem with that, however when I built and added an ETI 10-band per channel stereo graphic equaliser and set it up, I’d come home to find ‘my’ EQ settings had been changed to ‘his’ settings. We had very different ideas as to what sounded ‘good’. The owners of hyper-specced and similarly-priced audiophile systems often get their kicks not from music appreciation (after all, music can be enjoyed even on the cheapest of audio players) but from affording and assembling such systems, and then showing them off to their friends. While most sincerely believe those thousand-dollar, plutonium and powdered frankincense speaker cables made all the difference to the sound (only once they are burned-in of course), some of the best systems I’ve Celebrating 30 Years heard have been put together using decently-made individual components from yesteryear. A good example is the Sony SAVA15 Home Theatre system I purchased back in the mid-90s. I bought it on the same day I bought my first (and only) game console, a Sony PlayStation 1 and as I needed a decent sound system to enjoy the games I bought to play on it, this then-new Sony system was reasonably-priced and fitted the bill perfectly. This one is a little different than most home-theatre systems as we know them today. The amplifier is built into a heavy timber and mouldedplastic tower speaker (front left) while the right-hand cabinet holds the front right speakers and a sub-woofer. When one thinks of a sub-woofer, we usually imagine a 300mm, or more, heavyweight woofer built into an enclosure pointed towards the floor, but since there isn’t that much room inside the tower-style cabinet, or a hole in the bottom of it, the subby must be a lot smaller than that. Regardless of the reduced size, it certainly does the job! The towers are about a metre high and while mostly made from that thick, Weet-Bix-style particle board most speaker manufacturers love to use, they also have a thick, moulded plastic front with tuned audio ports exiting at the lower front face of the cabinet. The two front towers are connected via a flat, 4-metre long multicore cable. The whole thing doesn’t sound particularly appealing but it is a very well-made system and for its time also looked the part. It boasts a “virtual” centre speaker and two “rear” speakers in smaller hard plastic cabinets that siliconchip.com.au connect to the appropriate speaker terminals of the amplifier via 20-metrelong twin-core cables. If one only wants stereo, there is no need to set the rear speakers up. However, Alien Trilogy on the PS1 made good use of 5.1 surround sound and it was well worth the extra work wiring them in. Hearing a Xenomorph scream at you from somewhere in the blackness just behind your head is terrifying, and this would be a lot less effective in plain old stereo. The amp’s specs, from memory, are 100 watts/channel, with the window-rattling subwoofer being efficient enough to get me into trouble with my then-neighbours on more than one occasion. I still have this system in my workshop and I use it for amp and audio device testing and other menial audiorelated tasks. It is still an excellent system and we would still be using it as our main sound reinforcement in siliconchip.com.au the house, except for the fact that it developed a faint crackle in the lefthand channel a few years back. Rather than repair it straight away, we replaced it with another more modern – and supposedly better – LG Blu-ray capable system instead, thinking we were moving forward. I can’t help but feel that aside from the later technology of the included Blu-ray player (which I have never actually used to play a Blu-ray disc), it was actually a step backwards. A big difference I can see between the old and new systems is that the old system is designed to be repaired, with removable panels and recognisable components, whereas the LG uses many modular and proprietary components that, should one fail, are most likely difficult (if not impossible) to obtain. I haven’t tested that theory and so I might be off the mark, however experience leads me to believe this is likely Celebrating 30 Years the case. The one time I opened the case in an effort to find a part number on the Blu-ray/DVD player in order to find a hacked, region-free firmware for it, the actual module was like something I’ve never seen before or since, and I’ve seen a lot of those types of optical modules. My guess is that it is a proprietary part made specifically for this (or similar) systems and this is likely why noone had a firmware upgrade available for it. The Sony system had been assembled using what I like to call “analogue” components, that is, discrete transistors and capacitors that I can actually identify and swap out if necessary. Hybrid output modules are used, however they are clearly labelled and readily available should one fail. Another difference between the two is that I can barely lift the Sony system’s main speakers, while the spindly speaker towers on the new system could be thrown across the room by June 2018  59 anyone’s grandma with just one hand. Everything on it just feels tinny and somehow lacking, while the Sony has old-fashioned grunt and an innate sense of quality about it. It also sounds far better to me than the LG. I’m not alone in this either. Over the past few months I’ve had several older amplifiers through the workshop to be repaired. While their owners are pragmatic in knowing they might not be repairable, they would prefer me to assess the problems and rule that option out before they go looking for what they consider ‘inferior’ new equipment. They’d all spent considerable time and money back in the day setting up their ideal sound system and don’t particularly want to have to go through that again. While the market for speciality, high-end amplifiers has always been there and always will be, I am not really including that part of the market in this discussion because not many of us are prepared to shell out 10 grand plus for an amp and speakers (and cables) no matter how excellent they might sound. I’m guessing buyers of such systems would definitely have their gear repaired before buying new again. After all, not many of us could rationalise a purchase like that once, let alone twice! I’m talking about amps made by Pioneer, Marantz, Sony, Denon, Harman/Kardon and other quality brands that made some very good gear at (relatively) affordable prices. While some of this stuff was pricey 60 Silicon Chip back then, it had the quality to match and it is these amplifiers that are increasingly coming in for repair. These amps might not boast the very latest technology, but their specs are still very respectable and the hardware itself still worthy of investment to keep going. In most cases, they are incredibly well-made, have powerful output stages, and specs that are still superior to much of the tatt they sell at big-box stores today. Manufacturers today seem to think that the only specification that matters is output power (measured in Peak Music Power Output of course) and as far as looks go, they seem to compete for how many flashing lights and cheesy displays they can cram into their machines, not to mention speaker cabinets. Can you imagine a set of Silicon Chip Majestic speakers with blue and red flashing LEDs? I know, I know… One of the amps I had into the workshop recently is a Pioneer SX-950, a behemoth of a thing that weighs so much I had to use a sack-barrow to move it and the box it came in up the driveway to the workshop. I suppose the weight is the thing a lot of modern buyers don’t like, however to my mind this denotes a certain quality, as I know it will have a decent power transformer (and correspondingly strong chassis to contain it). I was right on both counts. After removing the timber and steel vented covers, I was struck first by the size of that transformer and again by the size of the two smoothing capacitors; both were 22,000µF 63V electrolytics and measured 50 x 110mm! There is also a weighty flywheel for the tuner’s dial cord assembly and various formed steel covers, grates and panels that all add up to heavy. It just oozes power and quality and this is precisely why the owner would rather try to have it repaired rather than simply dump it in the skip, as one would probably happily do with much of today’s more cheaply-built offerings! The problem with the amp? According to the customer, it was intermittent in switching on. That is, sometimes it would go and sometimes it wouldn’t. And when I say go, I mean that the panel lights would always come on but the sound wouldn’t always come out of the speakers. After quizzing the owner more Celebrating 30 Years closely about the symptoms, I learned that he could tell if it wasn’t going to go by the sound of the speaker/thump protection relay clicking; or not. If it gave a healthy-sounding mechanical clunk, he knew it would go. If instead it sounded weak and wheezy, he knew it wouldn’t. To resolve this, he simply switched it on and off a few times and in most instances, it would work properly after a few cycles. However, of-late, no amount of on/off cycling made a difference, so it was obviously time for an expert opinion. Since I didn’t know any experts, I’d have to be the one to take a look at it! A circuit diagram is a road map The handiest item to have when repairing anything electronic is a circuit diagram. It’s like having a road map in a strange city; with it, one can navigate around. Without it, one can still stumble around and may even find their destination, but the time wasted is non-recoverable (and mostly nonchargeable too!). Fortunately, like many owners of proper stereo gear, the owner had all the manuals and even a fold-out circuit diagram, though I barely needed it. Tracking down the protection board was as simple as following the speaker connections back until they hit the relay’s normally-open contacts. The relay sat on a socket on a PCB that also contained the circuitry that drove it. After carefully making sure there was nothing dangerously exposed, I plugged the amplifier in and turned it on, monitoring the voltage across the relay’s coil terminals. As the amp came to life, I could see the voltage rising on the coil, expecting to see the relay snap closed at around 23V; it didn’t. It did half-operate, with a little chatter, but it was certainly not a definite action. Before going further, I tried a few more times, as the owner would have done, to see if there was any difference; there wasn’t. The relay just wasn’t doing the business, which meant one of two things; the relay was tired and faulting, or the driver circuitry wasn’t supplying enough herbs to actuate the relay. First stop was the relay itself. It is a 24V 2A unit and, as in any quality amplifier, reaching it and removing it was a doddle. Two screws held it to the chassis and once they were removed siliconchip.com.au it easily pulled out of its socket. The clear plastic cover could also be removed by prying the base of it carefully up and away using the two clip access slots moulded into it on either side. No potted rubbish here! Under the microscope the contacts looked to be in poor condition. This could simply be a case of the contacts wearing out but to test the theory, I dialled in 24V on my bench power supply, limited the current and touched the leads to the coil terminals. The contacts closed, but not convincingly. Repeating the test a few times told me all I needed to know. This relay was tired and needed replacing. After a rummage through my spares, I found a similar relay and the downloaded datasheet confirmed the specs were identical, as was the pin layout. Another benefit of this type of gear; for the most part they used off-the-shelf parts, so replacements are easy to find. There’s even one available on AliExpress if push came to shove. I plugged the relay into the socket and screwed it down; I already knew it would resolve the issue and a quick power-on test confirmed it; the relay closed with an assuring clunk each time I switched the amp on and off. Reassembling everything was the reverse of disassembly and after wiring in some proper speakers, I had a nice afternoon listening to my favourite sounds, with periodic re-starts just to make sure. Another ‘proper’ stereo amp was saved from the landfill. Fixing costly gear on the cheap A. L. S., of Turramurra, NSW, recently had two similar faults in two different, expensive pieces of test equipment. Luckily, he was able to sort them both out... I managed to pick up a Rohde & Schwarz FSEA30 20Hz-3.5GHz spectrum analyser on eBay for a fraction of its original price, which would have been in the tens of thousands of dollars. It’s an older model but still very useful and the one I bought had been calibrated recently, in 2013. It looks a bit tatty but its self-test procedure confirms it is in fully working order. A bit of a bargain, really. The FSEA is great for audio analysis because of its displayed average noise level (DANL) of -110dBm at 1kHz and -159dBm at very low frequencies. It has a 1Hz resolution bandwidth (RBW) with a 1Hz video bandwidth (VBW) siliconchip.com.au Servicing Stories Wanted Do you have any good servicing stories that you would like to share in The Serviceman column in SILICON CHIP? If so, why not send those stories in to us? In doesn’t matter what the story is about as long as it’s in some way related to the electronics or electrical industries, to computers or even to car electronics. 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. and sweeps the entire spectrum in 5ms. Not many modern analysers are able to match this performance. The manual clearly states that the instrument retains its settings when turned off, however, this particular instrument did not. It seems like a minor fault but with an instrument of this complexity, there may be up to thirty button presses for a particular setting and having to set it up each time it was powered on was somewhat annoying! Foraging through the Rohde & Schwarz service manual, I found a small reference to an internal lithium battery which has a lifetime of approximately five years. No reference was given for this magical battery location, nor its voltage, except for a Rohde & Schwarz part number. Rohde & Schwarz advise in the manual that the instrument should be returned to them to replace this battery but because of the bargain basement price for the whole unit, an expensive factory repair was out of the question. I basically just resigned myself to setting the unit up from scratch each time I wanted to use it. Some weeks later, though, when I switched on the instrument, I got a “ratatat” noise from the cooling fan, as if something was stuck in the fan blade. Looking into the two fan inlets with a torch, I couldn’t spot anything obvious. Emergency surgery was now required to fix the fan and I figured that while the instrument was opened, the lithium battery could be easily replaced. Boy, was I wrong! Opening everything up exposed a complex array of seven large plug-in boards, each one completely shielded in its own metal jacket and each marked according to its function. The dreaded battery was nowhere to be seen and was certainly not marked. At least I could see the source of the fan problem. The air filter pads in front of the fans had perished and lumps of the rubberised filter had been chopped up by them. Big bits of material were floating all around the inside of the device, hiding most of the components in a pile of dusty fragments. I found that there were, in fact, four separate fans: two for the power supply, one for the CPU and another to cool the daughter boards. A vacuum cleaner sorted out the dust. However, this is dangerous due to the possibility of destructive static The Rohde & Schwarz FSEA30 20Hz-3.5GHz spectrum analyser sprang to life after the internal 3.6V lithium battery had been replaced. Celebrating 30 Years June 2018  61 With the PSU removed, it was relatively easy to access the CPU board via a metal panel and then, deep inside (the last place I visited), there was the board with the battery. I could not have been happier if I had won Lotto. It was a 3.6V lithium cell with pigtails, labelled “SAFT LS14250”. It was the size of half a AA cell and measured zero volts. I ordered two replacements from eBay. A Jaycar battery, Cat SB1771, is very similar and this was easily soldered in place to test everything. After reassembling the instrument, everything worked perfectly and it actually ran cooler than before. Removing the power supply from the inside of the Rohde & Schwarz UPL audio analyser helped to free the other boards for removal while searching for the CMOS battery. This battery ended up being a CR2032 cell located on the underside of the large PCB in the upper left of this photograph. discharge but because the weather was extremely wet and very humid at the time, keeping static down, I chanced it. I completely cleaned out all the fans and then began the search for the battery. I removed the demodulation board from the rack after unscrewing a keyway to permit access to the other connections for further vacuum cleaning. All the connectors were marked and photographed because of the complexity; otherwise, I would have difficulty when it came time to reassemble it. The battery was unlikely to be on any of the daughter boards because they provided optional features such as vector analysis, FFT and IF, with a couple of gaps for other options my unit lacks such as a tracking generator. I went to the most obvious place, the power supply unit, which was in a completely enclosed metal box. This was removed and opened after much blood and sweat (the tears came later) revealing four exposed PCBs stacked at all different angles (like a house of cards). Unfortunately, the nature of the battery such as its size, shape or voltage was not given in the manual but there was a component which looked like an AA-sized lithium battery. I had to remove it to see its actual markings. It was on a separate board which took an hour to extricate! Alas, it turned out to be a weird-looking Xrated capacitor! Reassembling the PSU required a Magician’s skills but when I finally had it put back together, I noticed a rattle inside and thought: oh no! One of one of the little washers must have come loose! It had to come out to prevent a possible destructive short circuit so the whole thing had to be pulled apart again right down to the metal chassis to remove it and then reassembled for a second time, hence the tears. So where was the battery? Searching the user manual (rather than the service manual) finally revealed the fact that the battery powered the CMOS RAM and was probably on the CPU board. Issues Getting Dog-Eared? Keep your copies safe with these handy binders Are your Silicon Chip copies getting damaged or dog-eared just lying around in a cupboard or on a shelf? REAL VALUE AT $16.95 * PLUS P & Order online from www.siliconchip.com.au/Shop/4 See website for overseas prices or call (02) 9939 3295. 62 Silicon Chip Celebrating 30 Years P The next culprit I then turned my attention to another fine eBay bargain, a Rohde & Schwarz model UPL audio analyser. This was eight years old when I purchased it and it cost a fraction of the $35,000+ new price. It was a real find because it had eight options including low distortion generators, jitter and interface tests and mobile phone acoustic testing analysis. All test functions are available on the analog and the digital interfaces. It also analyses analog signals in the digital domain and has the ability to set up an almost infinite array of audio filters including “brick wall” filters, something that other audio analysers cannot do because they usually require a separate filter board for each filter. Imagine my horror when some months after buying it, I switched on the UPL and it flashed up all sorts of messages such as “RAM battery low” (sound familiar?) and “hard disk is not detected” and then all sorts of gobbledygook symbols and so on! Re-booting created even more havoc and all sorts of beeps started to sound! The battery message had disappeared so I feared that the CPU was shot! Looking in the ‘basic’ UPL operating manual (462 pages long), I could find nothing on these particular messages. A UPL service manual was not to be found anywhere on the internet so I just switched it off and left it sadly sitting on the bench, hoping that a solution might be found. I was about to think of it as a rather expensive boat anchor but because of its relatively youthful age and its complexity I decided to send it off to Rohde and Schwarz for repair. I rang them siliconchip.com.au first to see if it was repairable in Sydney but sorry – no cigar! They would have to send it off to Germany to get a quote and this would cost $1,400, including the transport. Adding to this woe, they advised that this eight-year-old instrument was no longer supported and parts may not be available. But if parts were still in Germany, the cost of labour and repair could be up to (but not exceeding) $11,000! I can understand Rohde & Schwarz having to charge such fees because that would only just cover their costs to employ very specialised expert engineers to fix an instrument which I would consider to be one of the most complex on Earth. But this was about four times the price I paid for it so it seemed like too much of a gamble. I considered buying a new one but at that time, could not find any more second-hand dual domain Rohde & Schwarz UPLs at any price. I decided that perhaps I should have a go at repairing it myself. It was either that or the conversion to a boat anchor so I reluctantly decided to operate. By the way, while this is a very capable instrument, the learning curve involved in operating it is rather steep. My engineer friend who worked for Rohde & Schwarz said it was designed for someone with a PhD to operate and he is not too far wrong. Was I arrogant to assume that I could fix such a complex instrument? Well, there was no other realistic option. First, I scoured the internet but the only relevant information I could find was a small FAQ on the Rohde & Schwarz website regarding the audio analyser, entitled “hard disk not detected” where the question was “after a RAM battery change on the mainboard, the hard disk drive is not recognized anymore”. It then went on to describe a whole page of things to do: siliconchip.com. au/link/aajy Since the instrument had only displayed the flat battery message once that I saw, I was not convinced that this was the problem but I went on to have a look at the battery in question anyway. Opening the unit up, it was a puzzle just to work out where to start (see photo at upper left). Generally speaking, most complex test equipment is well-designed for performance but poorly designed for ease of service. siliconchip.com.au After replacing the CMOS battery the audio analyser was put back together and cleaned. However, it was still displaying the “hard disk not found” error message. Pressing the Page Up key on the machine booted into the BIOS and the correct settings could then be entered, allowing it to start properly. As with the FSEA spectrum analyser repair, the RAM battery was nowhere to be seen. In fact, it was not even obvious which was the “mainboard” that Rohde & Schwarz had referred to. The technique I used was to photograph all the boards and connectors then take the boards out one at a time. There appeared to be an order to disassembly but I was working without any information at all and even removed the hard disk drive, hoping that the mainboard would be beneath it. But that turned out to be incorrect. I removed the power supply and this seemed to be the key to releasing the other boards. I then came to a slightly larger board which had upwards-facing components. This had microscopic tracks, thousands of them, and I had to admire the exceptional engineering which had gone into it. Unfortunately, the component side was still mostly blocked by other bits so I couldn't see if the battery was there or not. I had to remove it and this took a fair bit of time. Finally, I was able to turn it over and there it was: a 2032 lithium button cell inserted into a battery holder! This was certainly unusual because all of the batteries I have replaced before in both HP/Agilent and Rohde & Schwarz instruments were solder types with either pigtails or PC pins. The cell measured 2.5V and replacing it took mere seconds. I then put everything back together, but took the opportunity to clean dust off all the boards and cleaned all the connectors Celebrating 30 Years with aerosol. I also took the opportunity to inspect the other components, in case there was another fault. After a couple of attempts, it all went back together and I screwed the cover on and fired the thing up. The same “hard disk not found” message popped up so I immediately grabbed the printed FAQ instructions to try and get it going. I did all this but they failed to mention what keys were needed to display the required settings. After hitting just about every key I could think of, “Page Up" finally did the job and I could proceed. Apparently, the hard disk drive is not connected to the mainboard but to the digital board, so you have to select the “Standard CMOS SETUP” folder and set the primary master as shown in this link: siliconchip.com. au/link/aajy The whole setup process took me a good hour but on restart, it still didn’t work. I ended up going through the process three more times before I got everything looking as per the FAQ. Then, bingo. The instrument sprung to life! I gave out a huge roar of “yes, yes, yes” and jumped up and down with sheer joy it was so satisfying to be triumphant over a machine and save $11,000. Also, all the options worked correctly and no permanent damage was noted. The instrument has performed without a glitch but I have kept the instructions with it because 2032 cells don't last long. But at least I can get them at the supermarket. SC June 2018  63