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A bit of a snag with the sausage rolls With a heading like that, one can assume there is an unusual story to follow. But what is a serviceman doing mixed up - if that's the right phrase - with sausage rolls? Well, everything's gone electronic these days, so it had to happen eventually. Truth to tell, this is not my story. It comes from a colleague who lives up the NSW north coast, in an area renowned for its tourist attractions and large holiday population. This is how he tells it. My mate's story Ordinarily, this is the last kind of job I would want to become involved in. It's hard enough keeping track of all the new model TV sets, video recorders, etc that seem to breed like rabbits in a 40-acre paddock but at least you know what they're supposed to do. With this device I hardly had that much to go on. So how did I become involved? It was one of those social links which is hard to ignore. The owner of the appliance - Charlie - lives only a couple of doors down the road, so we see each other frequently on that basis. In addition, we both own boats and belong to the local sailing club, so we see a lot of each other at that level too. And Charlie's a pretty decent bloke anyway, who has done me a few favours - all of which adds up when someone is in strife. Charlie is the local pastrycook and his business is quite large for a country area. It employs about 20 people in a factory on the edge of town and supplies a range of outlets up and down the coast for 50km or so, as well as his own outlet in the town. As well as the aforementioned sausage rolls, his products include meat pies, and a wide range of cakes and pastries. 34 SILICON CHIP One of his latest appliances is what might best be described as a sausage mince dispenser. It set him back some $6000 but, on the basis of what it was supposed to do and his needs, he considered it a sound investment. That may sound surprising but with a daily turnover of around 3000 pies and rolls, doling out dollops of mince with a spoon is hardly a proposition. And that's about all I knew about the thing up to this point. It was only recently that I first learned of his troubles. His reply to my "Ow yer goin' mate?" - politely translated - suggested that things weren't "goin"' too good. "It's that blankety blank sausage mince machine. Always packing up in the middle of a production run. Costs me a fortune in lost production time". I went through the motions of suggesting the appliance maker's service department or even the local electrician but it was a losing battle. It had already been back to the makers on two or three occasions - an expensive and lengthy procedure in itself - with little long term satisfaction. And the electrician freely admitted he was out of his depth. "It's the electronics in the thing", Charlie went on. 'Tm sure of that. Right up your alley really. Could you possibly have a look at it?" Put like that, how could I refuse? Thus it was that I found myself face to face with the machine while the factory was idle during the day. The main part was a heavy gauge stainless steel box, about 60cm square and 30cm high, mounted on castors for mobility. This contained an electric motor and pressure pump. Mounted on top of it was a funnel, about a metre high, with a top diameter of around 45cm, narrowing to about 6cm at the bottom where it entered the box. This was the input to the pressure pump and in use, would be loaded with raw mince. A post on the side of the box, about the same height, provided support for the top of the hopper. Emerging from the side of the box was a plastic hose, about three metres long and 5cm in diameter, with strands of reinforcing fabric moulded into it. This was the pump outlet. The other end of the hose terminated in a stainless steel nozzle, about 30cm long, slightly angled, and tapering to about 2.5cm at its outlet. There was also an operator's control button on the nozzle. In operation, the mince was forced out through the nozzle and applied to whatever pastry was involved. In making sausage rolls for example, the pastry would be laid out in strips about a metre long, a run of mince laid along it, the pastry rolled, then cut into lengths prior to baking. Up to this point everything described - bar the control button - was robust, well designed and ideal for an industrial application. Not so the control button and its associated cable which was supposed to control everything. The control button was a micro switch mounted in a plastic housing and was connected to the main control unit via a cable taped to the hose. The control unit The control unit was in a box mounted on the side of the machine. ~ "I know that it's rough", he admitted, "but it got us out of bother a few weeks ago. Now the whole thing's gone erratic again; I think it's about to pack it in completely". It certainly sounded like a more deep seated fault. Closer inspection showed that the control unit had its own power supply and could be easily detached from the machine. Having done that I disconnected the hose, then dumped the whole lot in the van and took it back to the workshop. I had several ideas about the button and cable but first I had to check the control unit. I Crude etching . . .~ff~ 1:. M"'ca~Asr.m• ~ e: U~G. 'RI N\lNC€- \ S \?.UT ;:;£ ___ ,__ 0 It appeared to be a small micro- processor and timer which controlled a relay in the pump motor circuit and offered the operator a number of options, selected by a button pad on the box. These included continuous feed with the nozzle button held down, a single delivery of a measured amount, or repetitive measured amounts, as used to fill a batch of pie crusts. Electronically, this was quite clever; mechanically, it left much to be desired. The control button housing was of flimsy plastic and the cable was a lightweight microphone variety, only about 2.5mm in diameter, taped to the underside of the hose. Since the hose and cable would be dragged across the concrete floor, and the nozzle would often be dropped on the concrete, it was no surprise that both had given trouble. The plastic housing and micro switch had been replaced several times, cracks in the housing allowing water to reach the micro switch when the nozzle was washed after each production run. The cable was badly worn and if not already faulty, was not far from it. In desperation Charlie had ditched the micro switch and substituted a fairly robust spring loaded pushbutton switch from the local service station. He had simply taped this to the side of the nozzle. I had no circuit of the thing but a visual inspection failed to reveal any obvious fault. But I was shocked at its appearance. The printed copper pattern was the crudest piece of etching I'd seen for a long time; the kind of thing you'd expect an experimenter to draw freehand with a resist pen. Beauty may be only skin deep but this was clearly indicative of the rough and ready approach to the whole electronic design. On the other hand, having disconnected the flimsy microphone cable and substituted a couple of clip leads, I couldn't fault its performance. I let it run while I worked on the button housing and fresh cable, tested it in all modes at regular intervals and it never missed a beat. So all I could do was press ahead with the obvious requirements and hope it wasn't a deep seated intermittent. My main concern was to get it all going for that night's shift. I decided to retain the auto switch Charlie had bought. It was a single hole mounting type, robust and reliable and while not totally waterproof, was no worse in that respect than the original micro switch assembly. The original plastic box was mounted on a metal plate which was then secured to the nozzle. I was lucky enough to have on hand a diecast aluminium box which was only slightly larger and this was easily fitted to the plate. With the switch mounted in the box it only remained to fit a new cable back to the control box. I was lucky here too; I had on hand an odd MARCH 1990 35 SERVICEMAN'S LOG -CTD length of professional microphone cable, two conductor plus shield, with a tough outer coating, about 6mm in diameter. Then it was back to the factory to reassemble everything. In the process I took the precaution of taping the cable in such a way that it would normally sit on top of the hose, rather than underneath it. A dummy run indicated that everything seemed to be working correctly and I left Charlie to organise the real thing later in the evening. As I learned the next day, it all went without a hitch - and has kept on going for the many weeks leading up to my writing these notes. Even so, I don't regard the setup as ideal. I'm hoping it will last 12 months or so while I find something better. I'd like a better switch and have been toying with the idea of a reed switch actuated by a permanent magnet. I've heard rumours of commercial versions of such an assembly and would like to track them down. I'd also like a better cable, perhaps an armoured variety if I can find one, that was light enough and flexible enough. In the meantime, Charlie is delighted, regards me as an electronic wizard, and happily paid me for my time. (There was never any suggestion that he wanted any favours in this regard; all he wanted was to get the thing fixed). Looking back I can't escape the feeling that the mechanical part of the appliance was a well established and proven design long before anyone decided to add the electronic features. And whoever did it may be very clever electronically but has a lot to learn about the practical side of industrial electronics. It doesn't work - but don't get me sta'r ted on that subject or I'll go on forever. So here's a complete change of scene - in more senses than one. From the north coast to the south coast, where another colleague is battling to cope with the vagaries of UHF transmissions - as have been dealt with extensively elswhere and problems unique to UHF equipment. As might be imagined, the main section unique to UHF - apart from the antenna - is the tuner, and that is what this story is all about; tuners and the problems of service. This is how he tells it. My other mate's story This all started with a fairly routine job involving a Sharp VCR, type VC9300. The owner's main complaint was that it had chewed up a couple of tapes. Then he added, almost as an afterthought, that he couldn't get it to work on UHF. The cause of the tape destruction was fairly obvious; it needed a new idler wheel, plus the usual routine cleaning, lubrication and adjustment of the various torques. That done I put it through its paces, making several recordings with a varie- Change of scene Well that's my mate's story and I couldn't agree more with his comments about industrial electronics. A common but misguided concept is that one can simply take the hardware of entertainment electronics and use it for industrial electronics. 36 SILICON CHIP TH~ 'Pf<l~EJ:> COPPe-R_ PA1f'ERl'l w~:s nu~: C.ROP6"S1"' Pf~C(; OF e.-rcttlNG l'l) SEEN FQ~ A LONG TIMG:-., ... ty of cassettes, and satisfied myself that the tape chewing problem was solved. Now for the tuner. I went over the VHF channels but found little to worry about, apart from a slight touch-up here and there. There was certainly no lack of sensitivity. Next, I tried the UHF channels. The owner was right; there wasn't even a flicker - just snow. I tuned right across the band but couldn't raise a sign of anything; and this in the presence of at least one local signal which delivers a millivolt or more from the antenna. The two possibilities here were that either the UHF tuner itself was faulty or that another fault was depriving it of correct operating voltages. In particular, the voltage on pin 8, which is a switching voltage to bring in the UHF section, is a prime suspect, failure of the associated transistor which switches this voltage on and off being a common fault. (The normal value is about 10V in the "on" position). I checked this and other appropriate voltages and all were correct. So it was the tuner. Tuners are quite complex things to service; it is a specialist job, undertaken by a number of independent organisations. Very few company service departments will handle them. Even worse, the latest designs are virtually non-repairable; chuck it away and buy a new one. Fortunately, this one didn't fall into that category and I deal with a repair organisation in the city for such service. On past experience, I expected this to take a bout three weeks; longer than I would like but about the best available. I advised the customer accordingly, adding a week for safety in case something went wrong. If only I'd known then what I know now. These things tend to slip one's mind with pressure of other jobs but after about five weeks the alarm bells started ringing. A phone call didn't produce a very satisfactory answer. The truth is that this firm is only an agency; they farm the work out to another organisation, which makes it just that much harder to chase things up. They were extremely vague WE:: KeP-r '-fOUR TH\ 'S U'°'F -r\l~R UHF 11J~R. ftJ A C.OP'&OA'RO R:'R 3 "(OU SEN'\ \JS 'BUR."11"' OUR it>AST' N\ONT\-\~ ... .& ,-r ,.._ SO "<OU CAN - f-\AVE:. 1-t'" ~~C.K FA\l--E'D -rt) S~OIJJ A S\NGt.-e: FAUL.1'" )/ V F\RM about the situation at first but after I made some jumping up and down noises - at STD rates - they said that it had been passed on to the service company and was still there. In reply to my request to hurry things along, they promised faithfully to do so. In the meantime, I had to do what I could to placate the customer. Spattered chips Three weeks later - still no tuner. Another phone call - I was spitting chips by now - and this time I insisted on speaking to a particular person who has been helpful in the past. Their answer was a real stopper; that person was on holidays and nobody else knew anything about the tuner. I'm afraid I blew up. In no uncertain language I demanded that they find someone who knew something about it and ring me back promptly, adding that I had no intention of holding onto an STD call while they waffled about. Three days went by and no response. I made another call and demanded to speak to the manager. With an effort I managed to remain calm long enough to explain the problem and request that he do something about it. He appeared to be sympathetic and promised to look into it and call me back. Two days later he called me. The tuner had been fixed, was on its way back to them and they would despatch it immediately. After another week, making the total count about 10, the tuner finally arrived. End of story? Not a bit of it! Brown dog You're not going to believe this; it was no better than before - absolutely dead. Fuming, I pulled it out and sent it back with a stiff note, saying do something about it and do it fast. And they did; it took only a week to get it back this time. And yes it did work but it was as sick as the proverbial brown dog. More precisely, I measured it as being at least 25dB down on normal. It needed a 5mV signal from the colour bar generator to produce even a snowy picture. This was so C bad that even I began to doubt my diagnosis. Was there another fault in the recorder? As luck would have it, an identical recorder came in for routine service. I pulled the tuner out - the tuner alone without its board and fitted it to the suspect machine. It worked perfectly. I rang the manager again and demanded that he do something about it. His reply was apologetic but not very informative. In the meantime, my customer was jumping up and down - and I couldn't blame him. So I pulled another trick; I gave the customer the manager's name and phone number and said, "Here, you give him a blast - two blasts might be better than one". It's a good trick. If nothing else, it convinces the customer that you are genuine. And in this case it might have helped. Anyway the manager rang back in a couple of days but only to say that the repair department claimed that there was nothing wrong with the tuner. How glad I was that I had tried MARCH 1990 37 SERVICEMAN'S LOG -CTD that substitute tuner. I was able to shoot that claim down in flames. I felt a bit sorry for the manager; he was the meat in the sandwich but I had to keep the pressure on. Anyway, he rang back in a couple of days, saying that the service department still claimed there was nothing wrong with the tuner but that they were sending me a replacement one. This duly arrived, was fitted, and worked perfectly; the final justification of my diagnosis and persistence. So, after about three months, I finally had a less unhappy customer. With hindsight I am convinced that nothing was done to the tuner the first time around. Something was fixed the second time, but performance was judged purely subjectively, probably using a strong signal from a nearby transmitter. On the basis of that episode, I had had a gutful as far as that firm was concerned. So, when faced TETIA TV TIP with a faulty tuner in a HMV colour set, C221 chassis, I sought the advice of a colleague. He recommended another company, firm B. I rang them. Yes, they knew the tuner and could provide a reconditioned replacement for a very reasonable fee. So I despatched the tuner, with a cheque, and crossed my fingers. Everything looked good at first - the replacement arrived in less than a week. You beaut! The joy was short lived. Sensitivity at the bottom end of the band SBS (Ch.52) and ABC (55) - was very poor. The next channel up WIN (59) - was suffering extreme cross modulation, and only Capital (62) and Prime (63) were worth watching. It had to be the tuner. So I pulled it out and sent it back, with a covering note detailing the faults. This time the round trip took about 10 days. Then the tuner arrived with a letter claiming that there was nothing wrong with it and that I Is Your Product Or Service Getting The Exposure It Deserves? Consumers need to see your product it you want them to buy it Contact Paul To Reserve This Space (02) 982 9553 Pye T30 chassis Symptom: No picture or very dark picture. Colour appears to be OK when turned up high and contrast control has some effect but brightness control does nothing. Collectors of the video output transistors are some 20V higher than normal. Cure : Plug and socket connection from brightness control, at bottom right corner of small signals board, either loose or suffering from corrosion on the pins. TET/A TV Tip is supplied by the Tasmanian branch of The Electronic Technicians' Institute of Australia. Contact Jim Lawler, 16 Adina St, Geilston Bay, Tasmania 7015. should check the antenna or the circuits supplying the tuner in the set. I regarded that as a classic "out" and something of an insult, to boot - particularly when I realised that this was not the same tuner (no AUDIO TRANSFORMED FOR PROFESSIONAL, OEM OR AMATEUR Broadcast quality aud io transformers ex-stock More than 70 standard types ava ilable Fast prototyping se rvice for non-standard types Comprehensive data available on request Loca ll y manufactured Competitively priced HARBUCH ELECTRONICS PTY LTD 90 George St.. HORNSBY NSW 2077 Phone (02)476-5854 38 SILICON CHIP mention of this), and even more so when I fitted it and it worked perfectly. Need I say more? My next experience involved several UHF tuners of the so-called mechanical variety. These are a continuous tuning type employing a variable tuning capacitor, made by General, but also used by other makers. I am currently holding a General (GC18A), a HMV and a Healing receiver, all needing service for this model tuner. In an effort to avoid more intestinal distress, I sought further advice. Firm C, a colleague assured me, was the one to deal with. I rang them and was assured that they could handle this model. So, cautiously, I sent one tuner for starters. It was back within week with a note saying that it could not be fixed, as it had been "bodgied". On closer inspection I had to agree that this was probably right. Fair enough. So I checked the other two, but they seemed clean, and I sent them off. These also came back in short order, with the advice that they were not repairable, but with no further explanation. But at least I must say this for that firm; they were honest and didn't muck me about. But I'm stuck with three sets which may have to be written off due to lack of adequate tuner service. All of which adds up to a rather grim outlook for this and other UHF areas as they are brought in. A major problem arises from the fact that all the tuner service centres are remote from these UHF regions and so have little knowledge of the practical problems, or the means to test tuners in the field. At best they are relying on instrument measurements but, more likely I suspect, often lack even this facility, depending on limited off-air observations. SILICON CHIP BINDERS quality * High up to 14 issues * Hold internal width * 80mm printed with * Gold SILICON CHIP logo on spine ,;;: /:~•.,•"::··,. . ,. >~}e-. ~" ,:'"' ,. ,~ ,.v · These beautifully made binders protect your copies of SILICON CHIP. In distinctive two-tone green high-quality vinyl specially selected for SILICON CHIP, and with heavy board covers, each binder holds a year's issues (the 14 issues of Vol.1 or the 12 issues of Vol.2). It will look great on your bookshelf. -------------------~-Yes! Please send me ____ SILICON CHIP binder(s) at $A11.95 plus $A3 p&p each (NZ p&p $A6). Name _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ __ (PLEASE PRINT) Street_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ __ Suburb/town _ _ _ _ _ _ _ _ _ _ _ Postcode _ _ _ _ __ End of story Enclosed is my cheque/money order for $ _ _ _ _ or please debit my Well that's it for this month. While both stories are a little out of the ordinary, the fact that they both come from country areas should help broaden our outlook and make us appreciate some of the problems D Bankcard D Visa Card D MasterCard faced by our country colleagues.~ Signature_ _ _ _ _ _ _ _ _ _ _ _ Card expiry date_---'--- L--------------------------' MARCH 1990 39