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SERVICEMAN’S LOG A mixed bag of odds, sods, ends and bobs Dave Thompson It’s sometimes a bit of a curse when people around the neighbourhood discover that I can do repairs on electronics and anything else vaguely related. I’ve had my fair share of food processors, heaters, amplifiers and CD players turn up just through word-of-mouth referrals. Don’t get me wrong; I welcome anything as a challenge. However, while sometimes the results are positive, that isn’t always the case. Recently, I had an 80s-era Phillips CD player through the workshop. This thing was likely audiophile quality back in the day, and the price tag (still stuck to the top) confirmed that at $3500 Kiwi bucks, you’d have to be a serious audio guy to buy it. I don’t think – aside from a house or a car – I’ve ever paid that much money for anything! Some of my old audio gear and guitars were getting up there in price, but 3.5 big ones for a CD player? Not for me! Anyway, this player had a problem. It would no longer open, and I got the impression the owner was more interested in getting the CD out of it than an actual repair. As with most older devices, getting any spares for it – like another CD player module – would be problematic. I told him what I tell most people in this situation: I’d open it up and have a look, and if I can do 68 Silicon Chip anything with it, I will; but if I can’t, well, that’s all there is to it. The machine was built like an external masonry water closet. Where one screw would suffice, they used three. All the plastic parts were also clipped onto the steel chassis. They certainly knew how to make stuff back then! None of this glue-the-two-halvestogether and throw-it-away-if-something-goes-wrong business. One thing they didn’t do was round off the stamped chassis edges. Not only was this unit really heavy but the exposed metal edges were like guillotines. As I’ve been caught before, slicing my hands open on poorly-finished metal fittings, I knew this time to be extremely careful how I handled it. I once picked up a heavy amplifier case and the sharp-edged chassis cut into all my middle knuckles. I couldn’t hold anything for weeks, which is a major pain in the rear (among other body parts). Lesson learned! I disassembled this CD player and when I got inside it, I discovered that the CD module was like nothing I’d seen before. I was hoping that it would at least be similar to the modern-day units you get for computers, DVD players and stereos, but no, it was completely different. Even the connections to it looked proprietary. Although the module was clearly labelled with part numbers, as usual, I couldn’t find any relatable information on the web about it; no service manuals or circuits for it anywhere. I also searched the likes of eBay and other auction sites to no avail. I went back to the Australia’s electronics magazine machine and looked to see if I could pinpoint what was actually going on with it. On power-up, the CD player just sat there hunting, as if looking for a disc. It wouldn’t open as it was working, and that’s all it did. Disc in or not, it just sat there looking. I suspected the laser had failed, and that’s what the rest of it was waiting for – the laser to report a disc was present, then it could complete booting and carry on. I have dozens of laser modules removed from CD and DVD drives; perhaps I could adapt one of these to this drive? Once again, it was all so different, and the laser module itself was a heavy-duty thing that looked like even a hammer wouldn’t touch it. I couldn’t even see the laser diode as it was embedded well inside the carrier. I could possibly get the old one out, but only using drills and such, so that wasn’t going to fly. Part of being a service or repair guy is knowing when to pull the pin on a job, and for me, this was that point. I had the disc out; all I had to do was manually turn the drive door pulley while there was no power present, opening the drawer bit by bit until I could move it all the way out. I reassembled the thing and, against all hope, tried it again, just in case the drawer would open and the thing would magically work. But no, it was, as far as I was concerned, end-of-life. I suggested to the owner that he might get more success from an established repair agent, who might have spares that would get it working, but he agreed that it had its day and it was time for a new one. At least I got the disc out of it. The next odd job Another neighbour arrived out of siliconchip.com.au Items Covered This Month • A mixed bag of odds, sods, • • ends and bobs Fixing the motor in a burnt-out clothes dryer A Kriesler radio and its capacitor firework *Dave Thompson runs PC Anytime in Christchurch, NZ. Website: www.pcanytime.co.nz Email: dave<at>pcanytime.co.nz the blue and asked if I knew anything about trailer lights. He’d recently had his trailer refurbished, with new incandescent taillights and an LED number-plate light and some of the cabling replaced. But some of those lights had already stopped working properly. Could I take a look? I suggested he should take it back to the people who’d refurbished it, but he said he already had several times, and they couldn’t find a fault in their work and weren’t prepared to spend any more time on it. I thought that was a bit rich, but the guy was clearly troubled by it, so I said I’d have a look over it and see what I could do. This was a standard trailer; nothing flash, just the sort of thing you’d fill up with rubbish or soil of a weekend and do a garden or dump run or similar. The lights and lenses all looked relatively new, as expected, but when hooked up to his car, he had no tail lights, and a brand-new LED numberplate light also didn’t work. The indicators did work, so that was something. The first thing I did was hook the trailer up to our own car; I wanted to rule out problems with his car’s fuses, power leads and trailer plug. Even though they are pretty hardy, trailer plugs can get a real hammering, and people can accidentally drop the trailer hitch onto the plug when moving the thing around, crushing it between the hitch and the road. However, once hooked up to our car, I got the same result as he did, indicating some kind of fault in the trailer wiring itself. This isn’t exactly rocket surgery; it’s basically a big tow-able wheelbarrow, but the inclusion of a wiring loom apparently elevates it to another level. In New Zealand, we use a heavyduty plug with seven contacts, and this plug hooks into a handy socket mounted on the car once the trailer is connected. I imagine it is the same connector used worldwide, but I don’t know for sure. Once connected, the indicators, brake lights and any other ancillary lights hooked into the system should ideally mirror the actions of the various rear lights on the car. My first step was to measure the voltages from the car’s socket and check that no shorts or high-­resistance joints were dropping the voltage. When I turned the lights or indicators on, or applied the brakes, I read the expected 12V (or near as reasonable) at all the correct pins. While colours for trailer wiring are supposed to be standardised, and most trailers are wired up correctly, there are plenty out there – perhaps built before the standards came in – with non-standard cabling. The wiring on this particular trailer was not standard, which made things a bit trickier. But due to the open nature of the plugs and sockets, one can readily deduce what coloured wire connects to what part of the circuit. And there’s another problem; ringing out a trailer loom with one person is tricky; I don’t have a three-metre arm span, nor do I have one of those tools for measuring connectivity in longer wiring looms. I ended up just using a small jumper lead with alligator clips at each end and connected one clip to a good clean spot on the trailer chassis and the other clip to each pin in turn at the connector end. I then used my multimeter with the buzzer function set to ALSO AVAILABLE 10% OFF YOUR NEXT DECEMBER ORDER WITH DISCOUNT CODE SCDEC10 FREE SHIPPING AUSTRALIA WIDE siliconchip.com.au THE TOOLS TO BUILD THE FUTURE w w w. p h i p p s e l e c t r o n i c s . co m Australia’s electronics magazine December 2021  69 span the ground and ‘live’ connections at the other end. It’s a bit of a faff walking backwards and forwards to set the clips, but with only seven big pins, it’s easy enough to do. I got identical results to the car-plugged-in tests, as expected. I took the non-working incandescent bulbs out of their sockets and tested them with the meter as well – all were fine, but I wanted to be thorough. Too many times, I’ve jumped the gun and had to backtrack over some silly missed problem like a blown light globe. Chasing a cable fault It appeared there was a lack of connectivity somewhere along the loom that connects the trailer socket to the lamps. The question was where. Two cables made up the loom on this trailer; both ran down a natural channel formed under the right-hand chassis rail before splitting at the right-rear light, and a single cable ran across the rear underside of the trailer and up to the left-hand light. Both were four-wire cables about the size of a standard mains lead and were strapped – some very tightly – using cable ties both together and to the chassis rails. Detecting breaks in longer cables is a bit of an art in itself, and while there are many methods using special tools and Wheatstone bridge-based machines and the like, I checked them using a ‘quick and dirty’ method. Using the jumper cable and multimeter once again, I connected one of my many dental picks to the non-grounded multimeter lead. I could then simply pierce the cable insulation and measure continuity along the length of the main cables, shifting the ground lead as I went along the loom. There’s a certain amount of educated guessing as to where the wires run within the insulation, and one could argue it exposes the inner wires to the elements. Still, the pick is so fine, and most trailer connections are exposed to the weather anyway, I didn’t see it as a problem. The main problem is the dental pick is dangerously sharp, so I had to take care not to miss the cable and find my fingers! At one of the tight cable tie points, I lost connection with the white wire in the bundle. This wire was terminated at the right-rear lamp, where it was split off using one of those plastic-coated inline crimp connectors to one wire leading to the LED number plate light. There was another similar connector for the second LED wire. That could explain why this wasn’t going either. That whole rear section of the loom was covered in 70 Silicon Chip poorly-­applied insulation tape, which I consider unsuitable for wiring sitting out in the weather. I’d have to re-do all that once I worked my way down there. I clipped the cable ties all along the loom down to the section where I thought it might be broken and marked that area with a bit of tape to avoid losing my place. I removed the cables from the right-rear light assembly and pulled them back through the chassis rail so I could easily get to the dodgy section. This would also make it easier to add proper heatshrink tubing where needed eventually. I was a bit surprised to find that the wiring simply enters the body of the taillights through a largeish hole in the backplate. In my opinion, this is a design flaw; as the lights hang directly behind the wheels, they can fill up with water and road grime flung up from the tyre through that hole. Now for the tricky part, peeling away the insulation around the fault. I didn’t want to replace the whole loom from front to back but would do so if push came to shove. I’ve in-lined joints before, and that shouldn’t be too much of a problem on a low-voltage system. I carefully split the insulation on either side of the suspected fault with the tip of a craft knife about 5cm along the ‘grain’ of the cable, being very careful not to carve anything else inside. Now having access to the crushed section, I could move the other three wires out of the way and check the white wire. I simply pulled on it a little, and a small section of insulation stretched, telling me the wire inside had parted company. I snipped it at that point and, sure enough, cut only through the plastic. Of course, if I stripped back the insulation and simply re-soldered this wire together, it would be shorter than the others, creating a messy join. Instead, I stripped it back on each side and installed some heatshrink tubing before using a brass ferrule to make up the length difference. A thorough crimp had it back to size without a lot of bulk, and after shrinking the tubing over the ferrule with a heat gun, I fed suitable large-sized self-amalgamating heatshrink tape down to cover that area of the loom. Once again, the heat gun had the tube down to size, and the amalgamation would see it well-sealed in there. Almost there With that area done, I went back to the rear end. I fed the loom roughly back into place and reconnected everything back to the light assembly. I wanted to test it before I went any further. This time, when it was all plugged in, I got brake lights and tail lights but, frustratingly, still no number plate light. Looking at the mess of how it had been connected into the loom, there was no wonder. Once again, I got the multimeter out, and while I had voltage to the point of the connectors that split the loom off to the LED, I got nothing after them. Hopefully, all I’d need to do is replace those inline connectors to get it working because the LED assembly had been riveted to the tailgate, and I didn’t want to have to drill those big rivets out. They had already cracked the plastic housing and I was reluctant to cause any more trauma to it. The people who had installed the LED had left plenty of cable length, so chopping out the connectors wouldn’t be a problem. I soldered those wires back together (after Australia’s electronics magazine siliconchip.com.au installing suitable heatshrink) and, when tested, it all worked properly. I then took the loom back out and fitted more heatshrink tape – all this would tidy up that insulation-tape mess. Now when everything was reconnected and appropriately cable-tied, the lights worked a treat, and the wiring installation looked a whole lot better. Job done! I wonder why the original installers couldn’t figure it out. You don’t have to be Wile E. Coyote, super-genius... Fixing the motor in a burnt-out clothes dryer A. L. S., of Turramurra, NSW had to take a guess at what had failed so he could order a replacement part before he’d disassembled the failed unit. His guess was close enough to result in a successful repair... Returning home one day, my wife came running out to greet me with “there’s been a disaster!” Our 5kg Simpson clothes dryer (39S500M) had stopped working and had emitted clouds of smoke, setting off the smoke alarm and filling the house with an evil smell! The smell from this dead dryer was slightly different from the usual burnt-out transformer smell that I was familiar with. It had the odour of a stale ashtray. My wife said it smelled like a car had done a burnout in the house, but I put it all down to the type of insulation enamel. My wife thought it was best to throw the dryer away because it was over 20 years old, and I agreed. But when I checked out the reviews of the newer high-tech programmable model, several reviewers gave it only two stars, and a couple of buyers regretted buying it. That’s because it has a sensor that is supposed to detect lower humidity and shuts down the “program” when it sees fit. The problem is that if the user disagrees with the decision of the dryer, they can’t dry the clothes for five or ten minutes more if the items are still damp! My wife also preferred the old-fashion timer and was very adept at setting the timer for various items. So I suggested that I have a go at fixing it because I was sure it was a burnt-out motor, and there were plenty of second-hand and re-conditioned replacements available online at reasonable prices. I could also find plenty of siliconchip.com.au Australia’s electronics magazine December 2021  71 other replacement parts such as drive belts, timers and odds and sods, which made me think that this model was infinitely repairable! She agreed but did not want me to pull it apart yet to avoid a mess in the laundry. So I took a gamble and bought what looked like a pretty good used motor (part #0214377106) for $69 online, which arrived after about two weeks. I tested it on the bench with a temporary AC mains supply, and it seemed very strong and noiseless, so it was time to operate and replace the faulty one. Before I could remove and dismantle the dryer, the kindly next-door neighbour (who enjoys working out at the local gym) helped me pull it off the wall. I then set about removing the screws from the back panel and took off the small nut which held the drying drum in place. Inside, I found three connectors: one for the incoming mains, one for the motor, and one for the heating element. These are tricky because they are hard to access; the sheet metal was really sharp, and my wrists were in danger of being slashed. It didn’t help that the wires were very short, and there was a narrow gap between the connectors and the edges of the back panel. I used thick leather gloves to help separate them, and then I could remove the back panel. I then removed the drive belt from the motor assembly and extracted the big drying drum for cleaning and inspection. The guts were full of dust and lint, so I vacuumed it out to see where all the screws were. I could just see some burnt lint around the motor capacitor. I used a 6.5mm socket on an extended shaft to remove all the screws holding the motor in place. The fan and shrouding had to be unbolted at the same time. Finally, it all came out, and I was able to see that the capacitor which was bolted to the motor had a cavernous hole (which was definitely not an inspection hole), and it had oozed molten metal all over the motor. The 8μF 450VAC rated capacitor had overheated and spilt its guts (shown below)! That explained the smell; a burning capacitor smells different to burnt windings. There was a thermal cutout, but this was mounted beside the motor on a piece of tin. Since the motor itself had not overheated, the full mains voltage remained active across the capacitor. Luckily, my wife had switched it off as soon as the smoke alarm activated; otherwise, it could have started a fire. Fortunately, the new second-hand motor was identical to the old one and also had the 8μF 450V capacitor attached, which looked very fresh. So I replaced both the motor and capacitor. Before everything could be reassembled, I filled a bucket with the lint I removed! My wife is very particular and empties the external filter assembly before every drying cycle. Obviously, that was not enough to prevent a huge buildup over 20 years. Perhaps this contributed to the demise of the This 8μF capacitor had overheated and leaked all over the motor. 72 Silicon Chip Australia’s electronics magazine motor capacitor; the rear ventilation slots were blocked, so there was no air cooling. Cleaning it up took me quite a few hours; I had to use a hose to wash the separated parts, allow them to dry and then reassemble them carefully. The motor bolted into place easily enough, and I threaded the belt arrangement by holding the tensioning spring back. You need to settle the belt onto the drum by rotating the motor by hand for at least two drum rotations before applying power; otherwise, it will instantly throw it off. Satisfied that all was good, I plugged in the repaired dryer, stood well back and set it going. It operated noiselessly and smoothly, and my wife and I watched it for a few minutes just like a new TV set. We were very happy that we had saved a few hundred bucks getting our dryer back in action! A Kriesler radio and its aluminium capacitor firework R. M., of Scotsdale, WA heard a knock at the door, and it was his mate Kevin, holding something that looked like a spent firecracker. It wasn’t, though... “I got this really good looking old radiogram, got it working, and it suddenly went bang! And I found this inside!” said Kevin. It did look a lot like a demised firework. About 12mm in diameter and 50mm long, tightly wrapped paper and foil, with one end showing definite signs of having exploded. When I realised the foil was aluminium, it clicked. I was holding the guts of an old high-voltage electrolytic capacitor. Having been retired for years, it had objected to suddenly being hit with volts and responded appropriately. A bit of leakage current, a buildup of heat and pressure, and bang’s your uncle. I offered to take a look at the radio, and it shows up the next day. It was a nice looking unit, a classic mid-20thcentury Kriesler in excellent condition. Someone had been taking very good care of it – I caught a whiff of furniture polish. Lifting up the lid, there was the large glass dial with an imposing array of knobs, and a record changer in a recess to the left. The cabinet was OK, but the innards might not match. Removing the Masonite back and a couple of long screws loosened the top part of the siliconchip.com.au deck, the dial swung up and released the chassis. I wriggled it out and onto the bench. I’d forgotten how heavy these things were! The top looked clean with no apparent damage, but underneath was another story... Within the usual tangle of pointto-point wiring, there was the empty aluminium can of an axial electrolytic. The end cap had been blasted away and hung forlornly from its solder tag. The once-liquid part of the contents was a grey goo sprayed all over the inside of the chassis. Luckily, it was facing away from most of the circuitry and expended its venom into a basically unpopulated corner. One thing that had copped the lot was the red active mains power lead. The rubber insulation had decomposed over the years, and it was stripped bare. The only reason it wasn’t shorting was that it was reasonably stiff and well-anchored. With judicious use of compressed air and a toothbrush, the chassis cleaned up nicely. All the rest of the circuitry looked good. I decided to make some quick checks to see if it was safe to proceed. I plugged it into a Variac and cautiously upped the volts. No smoke appeared, and the dial lights and all the six valve filaments lit up. I managed to connect one speaker and got a lot of hum, but also recognisable audio. One pleasant surprise was a copy of the circuit diagram stuck to the back panel. It was a bit faded and discoloured. Editor’s note: we have supplied another scanned version of this circuit. There were four filter caps on the high-voltage lines with their values clearly marked. 32μF, 50μF, 16μF and 8μF. The local electronic suppliers didn’t stock caps rated at 400V, but element14 did, so I ordered all four online. Next, it was time to replace that damaged power lead. Kev had thoughtfully looped up the slack lead and secured it with a cable tie. It seemed a bit long, and the plug looked modern, as did that end of the cable. I cut the tie and unwound the full length of the power cord, or should I say cords. The old cord was joined to a new one by a suspicious large insulation-tape-­ covered bump. Taking off the tape revealed a terminal block with just two joiners: Active and Neutral. There was no Earth connection because the extra length of cable was twin flex, with a three-pin plug but no green/yellow striped wire! This resulted in Kevin receiving a stern lecture on electrical safety. With the new capacitors fitted, it was time for the big test. I switched it on and wait for the old electronics to build up steam, then I got a glorious burst of ABC radio. I thought I’d better check the record player next. The complicated autochanger mechanism looked clean, and the bits moved freely, so I dug out an old 78 RPM disc and put that on the turntable. After lowering the pickup, there was a rush of snap, crackle and pop followed by music. But only through one speaker. I checked the balance control, but it was centred. Only one speaker was working now, but with the radio, both had given their best. An inspection of the ceramic cartridge told the tale – decomposing rubber again. The little flexible bridge that joins the stylus to the left and right piezoelectric elements had rotted badly and completely lost one leg. According to the label, the radiogram was made in 1965. What’s the chance of finding a new cartridge for that? Actually, it was easy; a bit of checking around and I found a replacement. It cost $70, but I now had two-channel mono. To make sure nothing else was going to blow up, I left the radio running for a day. There were no problems, so the nostalgia box went back to a happy Kev. The capacitors cost around $40, so for just over a hundred bucks, he was happily grooving along to the sweet sounds of his extensive collection of SC records. The circuit for the Kriesler 11-98 manufactured in 1965, scanned from Philip Leahy’s HRSA Circuit Book 5. siliconchip.com.au Australia’s electronics magazine December 2021  73