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SERVICEMAN'S LOG Some customers can be a real pain There is a good deal more to the service game than learning how to service TV sets, video recorders & other odd appliances which turn up from time to time. One also has to learn how to deal with customers – and that can sometimes be a lot harder! To be fair, most customers are not hard to get on with – not deliberately, anyway. Granted, their naive ideas about elec­tronic equipment and their clumsy attempts to describe symptoms can sometimes prove extremely frustrating but one learns to live with that. And a patient approach usually wins out in the end. But as I’m sure any of my colleagues will testify, every once in a while one encounters a really nasty one; someone who deliberately sets out to be as hard to get on with as possible. I imagine that, basically, it stems from an almost paranoid suspi­ cion that all service personnel – plumbers, electricians, motor mechanics and, of course, TV technicians – are rogues intent on ripping off the customer. 30  Silicon Chip Well, no doubt some of them are; it would be foolish to believe otherwise. And a healthy suspicion on the part of the customer is good protection –caveat emptor (let the buyer be­ware) and all that, as they say in the classics. But “all that” needs to be tempered with some discretion and common sense. The customer needs to take a little time and ask a few polite questions before reaching a conclusion. An honest technician will give logical, easy-to-understand answers; he has nothing to fear. How it started OK, so what started all this? First, in order that the reader can follow the story, it is necessary to provide a little background, before getting to the nitty-gritty. Some three or four years ago, a local dealer began handling Grundig TV sets. The Grundig is an up-market European brand which first appeared on the Australian market with the advent of colour TV. It remained on the market for a few years and then just seemed to fade away. The next I heard of Grundig was when the local dealer began stocking them. Initially, I had no particular interest in them until about a year ago when the dealer approached me about a set, still on his showroom floor, that was giving trouble. And, exhibiting an almost child-like confidence in my skill, he de­clared it was something which he was sure I could fix in five minutes! Naturally, it wasn’t that easy and the first thing I needed was a service manual. To obtain this, I rang the company responsible for importing these set’s and was put through to the managing director. He proved to be most obliging and helpful. Not only did he promise to put a manual in the post immediately but, when I quoted the set’s model number and the symptoms, he made some suggestions as to the likely cause of the problem. The manual arrived promptly and, with its aid and the suggestions, I quickly located the problem. A dry joint had destroyed the horizontal output transistor, plus an IC which drives this transistor. It was all perfectly routine and the set was repaired and returned to the dealer. And that started the ball rolling. My dealer colleague suggested I undertake warranty service for these sets, since he needed effective local warranty back-up as part of his sales package. I didn’t rush in; I needed to clarify the kind of deal I could expect from the importer; ie, technical back-up, parts availability and the financial basis for warranty jobs. This resulted in some telephone discussions and then a visit to their premises, which proved to be quite impressive. They were well organised, had a very good service set-up, an excellent stock of spare parts, and warranty payment and condi­tions in line with usual practice. And so a mutually satisfactory agreement was reached. Nothing much happened at this level for the next few months. By all accounts, Grundig TV sets are very reliable. Madam calls Then the phone rang and I quickly sensed trouble. The call­er, a woman with a rather imperious manner, indicated that she owned a Grundig TV set (model ST-70/460) which had failed and that she had been referred to me by the dealer. There was no suggestion of a warranty claim as the set was well outside this period, but she wanted me to come to her house, at that very instant, and fix the set. And it wasn’t simply a request; it was delivered more in the manner of a royal command. I replied, as quietly as I could, that I was very sorry but I could not come at that very instant; I was busy in the work­shop. I would be able to call the following afternoon, collect the set, bring it to the workshop, service it and return it. And I added that there would be a pick-up and delivery charge. “Oh no. That is totally unsatisfactory. No way. The set has to be repaired in the house”. Again I had to politely refuse. “I’m sorry but there is no way that I will attempt to repair the set in the house. I have no way of knowing what spare parts I will require, nor can I do a proper job without access to suitable test equipment”. Initially, she wouldn’t budge and tried to argue. But I wouldn’t budge either and I really had the whip hand. Eventually, very grudgingly, she agreed to let me take the set and so an ap­pointment was made for the following afternoon. Unfortunately, when I fronted up the next day, it was all to no avail. The front door wasn’t even opened. Instead, the husband came around the side of the house and informed me that my services were no longer required; the set was now OK. I accepted the situation in good grace and went on my way. But I wasn’t very happy. I felt that they might at least have had the decency to phone me and save me a time-wasting trip. But that’s the luck of the game. The truth is, I suspected that they had approached someone else to do the job. Madam complains In any case, I imagined that that was the end of the mat­ter. But no; about three weeks later I received a phone call from the managing director of the importing company. And I sensed that he was a mite put out. It appeared that he had been contact­ed by one of the party – presumably the woman – and told that I wouldn’t come to the house and look at the set. Well, I lost no time in putting him straight. And he didn’t take too much convincing. More to the point, he supported every­thing I had done and indicated his intention of ringing the customer and straightening things out. And he was as good as his word. Some 20 minutes later, a considerably mollified woman was on the phone wanting to know when I could pick up the set. It was early in the week and I had a pretty full schedule. The best I could offer was the following Saturday morning. No; that was no good. After some mumbling, she finally suggested that they would bring the set in themselves, on the Thursday afternoon. I said that that was fine by me and so that was how we left it. You’re not going to believe this next bit – or perhaps you’re way ahead of me. Thursday came and went with no sign of the set, as did Friday and Saturday. Then, on the following Wed­ nesday, the woman was on the phone again. I had been called away rather urgently at the time and had left the shop in the care of an assistant. And she copped the woman’s wrath full blast – a real tear-a-strip-off job because I hadn’t collected the set. Fortunately, my assistant was fully aware of situation and gave as good as she received. More specifically, she pointed out that the arrangement was for the customer to deliver the set. This was vigorously denied by the customer and so the conversation ended in a stalemate. Next morning I was on the phone first thing. The woman answered, which was fortunate since she seemed to be the one doing all the stirring. I reminded her of the arrangement whereby she and her husband were to deliver the set but again this was denied. She was obviously prepared to argue indefinitely over this until I pointed out that I had written the arrangement in my workshop diary. Only then did she stop arguing and agree that I should collect the set. And so a further appointment was made. And this time it worked. I was June 1993  31 SERVICEMAN'S LOG – CTD greeted at the door, almost affably, and shown into the lounge room. The house was very modern and the lounge room very large and expensively furnished. Along the full length of one wall was a built-in, glass fronted, cupboard which ran from the floor to about chest height. The TV set sat on top of this, along with an impressive hifi system. But what struck me was the fact that the shelf formed by the top of the cupboard was only just deep enough to accommodate the TV set. The point about all this was that it was quite a tricky job disconnecting the leads and plugs from the back of the set. As well as the antenna and power cord, there was a cable to the amplifier system which connected to the set via a European multi-pin SCART socket. Moving the set forward, or swinging it around, created a dangerously un- 32  Silicon Chip stable situation and I had to support it with one hand while working on these various leads. I managed OK but it was obvious that any idea of working on the set in-situ was completely out of the question, quite apart from any other con­ siderations. Nor were there any tables in the room; the only place to work was on the carpet. And I doubt whether Madam would have approved of that. Anyway, with some help from her husband, the set was even­tually loaded into the van and taken back to the shop. But one other point had been raised while I was there. Madam insisted that I submit a quote for the job, before proceeding. Madam’s quote Now this is something I normally do not do. Nor do most other servicemen that I know. It’s simply not practical in this game. In a great many cases, there is no way of assessing the cost until the job is finished, by which time one has already expended time and effort. And while the failure of one component may be obvious, there’s no way of knowing whether other compon­ ents have been damaged or how long it’s going to take to find the reason for the failure. When customers raise this matter, I point out that, if I did quote, it would have to be a high enough to cover almost all contingencies. But then, if it turns out to be something minor, I can be accused of ripping them off – or quoting a rip-off price. Most people accept this and I am always prepared to put a limit on costs, beyond which I will not go without consultation. Even this involves some risk but it’s one that I’m prepared to take. So what did I do about Madam’s demand? I’m afraid I took the coward’s way out. I’d had enough confrontation and, since I already had some idea of the likely fault, I reckoned I could break the rules for once and work around this one. And so, at long last, the set was on the bench and I could get on with the real job. At switch-on it was immediately obvious that the switchmode power supply had shut down. And the number one suspect in almost all such cases is the horizontal output transistor, or something very close to it. The relevant portion of the circuit is reproduced here (see Fig.1) and shows this transistor (T541, BU508A) and its associat­ed driver IC (IC500, TDA8140). This latter arrangement differs from that usually encountered, where a driver transistor and coupling transformer are used. Anyway, a quick measurement of T541 confirmed that it had cashed in its chips. And, acting on advice I had received from the importer, I suspected that the driver IC would also have failed. And so it proved to be. I had both these components in stock and it was a routine job to fit them. But I had no illusions that I had found the real fault; almost certainly, these were merely the victims. And again the service personnel’s advice proved to be spot on. I went to the tripler (K536) which, along with the horizon­ t al output transformer, is located in the right rear corner of the set. A close examination of this component revealed a small break in the plastic case. I fed the set from a Variac and wound the voltage up slowly while watching the tripler. Sure enough, as I approached the normal input voltage, a telltale corona appeared. I switched off immediately but I had also seen enough to suggest that the set would operate normally. So a new tripler was needed and I had one of these in stock also (they are not cheap, by the way). This was fitted and the set came good immediately. I made a few minor adjustments and the set was back to new condition. But what about Madam’s insistence on a quote before pro­ceeding? Well, of course, I had needed to “proceed” before I could assess the cost and this situation is a classic example of the futility of customers insisting on a quote. Anyway, I toted up the bill and as a matter of interest it worked out as follows: Labour plus transport ............$125.00 BU508A transistor .....................$8.00 Tripler ....................................$116.38 TDA8140 driver IC ..................$59.60 Postage on components .............$5.00 Total .......................................$313.98 I’d taken something of a punt, of course. How would I stand if, when I presented the above as a quote, the customer knocked it back? Well, of course, I hoped that it wasn’t going to happen. But considering the aggro I been through so far, I was even pre­ pared to offer to put the faulty parts back and give them back the set, no charge. Drastic? Of course – but I wonder what they would have done. In the event, it was all hypothetical. I rang the house and Madam herself answered the phone. Seeking to break the ice a little, I facetiously pulled the old gag of asking which she wanted first; the good news or the bad news. I should have known better; the gag fell completely flat (I doubt whether anyone ever laughs in that household). So I carried on bravely: “the good news is that there is no problem about repairing the set. The bad news is that it is going to cost you $314.00”. Madam agrees I fully expected a violent backlash at that figure. But no; all the woman Fig.1: the horizontal output stage in the Grundig ST-70/460 colour TV receiver. The use of an IC driver stage (IC500) for the horizontal output transistor (T541) is rather unusual. said was, “how soon can we have the set back?” I said it would take about three days. There were a couple of reasons for the delay. One was purely diplomatic; she had no idea that the job was finished. The other was genuinely technical; I wanted to give the set a good soak test before I returned it. The last thing I needed was for it to bounce. So another appointment was made and this time everything went without a hitch. I was greeted courteously, the husband helped me in with the set, and we set it up on the bookcase. I switched it on and the sight of a first class picture was ob­viously reassuring. This photo clearly shows the crack in the case of the tripler (K536). The small white plastic box houses the 30MΩ focus control variable resistor. Then I presented the itemised account. I was half expecting a grumble when the figure was digested. But no; the husband pulled out his wallet and handed me three $100 notes plus a twenty. I reached for the necessary change but he waved it away. “No way; that’s near enough. And I don’t even want the docket.” I protested that the gesture wasn’t necessary but he in­sisted and I gave in. But Madam showed her mettle by insisting on keeping the docket. Which was no skin off my nose; I had nothing to hide. Why did it happen? And that was the end of my ordeal. But why did it all hap­pen? Technically, I am now certain that the first failure was simply a power supply shut-down caused by the tripler but without any damage. Had they let me take the set then, I would have only needed to replace the tripler and they would have saved quite a few dollars. But when it came good temporarily, I was sent pack­ing. Domestically, there seems little doubt that there was a difference of opinion as to how and by whom the TV set should be repaired. This situation became quite clear when I encountered both parties together when I returned the set. The husband simply wanted the set fixed, without any hag­ gling or mucking about. Madam, on the other hand, treated me with rudeness and suspicion from the outset. She was June 1993  33 SERVICEMAN'S LOG – CTD was intrigued to learn about how this valve was to be used and in what kind of equipment. I took the valve with me the next time I went to town and as I handed it over to the salesman I asked if he could tell me who wanted it. All he knew was that it had been ordered by the local Cadburys chocolate factory but he had no idea what it was to be used for. He promised to enquire for me when someone from the company called to pick it up. Metal detector This is the Cintel IMD (Industrial Metal Detector) in the Cadburys chocolate factory. The 40-year old design can detect metal fragments that are just 0.5mm in diameter. also determined to have it all done her way and to drive the hardest possible bargain. Well, it didn’t turn out to be much of a bargain in the end. There’s one final snippet. I wasn’t the only one Madam dobbed in. While she was dobbing me in she also dobbed in my dealer colleague. Her story to the distribution company was that the dealer had indicated that he was no longer handling Grundig sets. This was her garbled version of the dealer’s state­ment that he did not service the sets; that they should be re­ferred to yours truly, as an accredited Grundig service agent. Fortunately, a few phone calls soon straightened things out but I think you can see what I mean by some people being delib­ erately hard to get on with. Apples & chocolates Well, after that, we need a complete change of scene. And who better to provide it than our old colleague, J. L. from Tas­mania, the land of apples and chocolates. This is his story about the latter. This is not a “Serviceman” story in the usual sense. In­stead, it’s a look at servicing in an entirely different field to that seen by most of us. What’s more, it turned out to be a very sweet exercise, in more ways than one! 34  Silicon Chip A few weeks ago the phone rang and the voice on the other end asked if I had a 6J6 that I could let him have. It turned out to be one of the staff at a city trade house and he wanted the item for one of their industrial clients. Now, I had to stop and think what a 6J6 was. You don’t hear words like that much these days. It turns out that a 6J6 was twin triode RF amplifier valve and, as you all know, RF amplifier valves went the same way as button-up boots. I’ve had no call for new valves for over 10 years and what is left of my stock is stowed away under the house amid thick dust and spider webs. But if someone actually wants to buy a valve, I don’t mind braving the creepy-crawlies to find one. So half an hour later I had found a 6J6, brand new in its original carton. It was the only one of its type I had and that made me wonder just what was special about this valve. Most other valve types are represented in my collection by the dozen. Why was this one there by its lonesome self? The 6J6 is an RF amplifier twin triode. It has the cathodes of each triode tied to a single base pin. I have never seen such an arrangement in any TV tuner (the most likely place to find RF amplifiers) nor in the front-end of any radio that I have ever worked on. So I The valve was duly collected but all he could learn was that it was for use in a metal detector and had been ordered by the purchasing officer. I was on my own if I wanted any more informa­tion. It occurred to me that any equipment that used valves should now be classified as “antique” and if some such equipment was still being serviced, then there must be a good story behind it. Ac­cordingly, I rang the factory the next day and spoke to the purchasing officer. He put me in touch with the assistant elec­trical engineer, who subsequently showed me through the factory and let me see the old valve-type metal detector that started this story. The equipment is a “Cintel IMD” (Industrial Metal Detector) and I learn­ ed that it, and some 20 others, had been installed in 1957/58 as part of the company’s on-going quality control pro­gram. About five of the machines remain in service, although only one is still in continuous operation. Their places have largely been taken by several different types of solid state detectors. The company’s Purchasing Officer was able to give me the full history of the remaining Cintel IMD. He brought out the original Assets Book and showed me where the machine had been ordered in September 1957, delivered in April 1958 and installed and working in June 1958. He was also able to tell me the price paid for it – 521 pounds (or $1042). When the Cintel finally retires, it will be replaced with a modern solid state machine costing just a shade under $250,000. I was also introduced to the Assistant Supervisor (electri­cal) and taken on a tour of the factory, to see how electronics had been introduced into the confectionery industry. The first thing we looked at was the Cintel IMD. This machine scans an 80cm wide production line conveyor belt, looking for any metal that may have been introduced into the product. When it was ordered, the specification was that the machine had to be able to detect a 2mm metal ball anywhere across the line. It easily succeeded in this task but, over the years, the technicians have tweaked and tuned it so that the Cintel can now detect a piece of metal only 0.5mm wide near the centre of the line, and even smaller at the edges. For all their refinement, the modern solid state machines can do no better. The power head of the Cintel IMD contains comparatively little electronics. There are only five valves in the unit, and all connections are hard-wired to terminal strips under the chassis. The 6J6 valve is used as an RF oscillator, followed by a buffer, a driver and a push-pull output stage. Apart from valve failures, the problem which started this story, there has been remarkably little trouble with the old machines. The most serious occurred some 10 years after they were installed, when there were a series of breakdowns when they were restarted after the Christmas shut-down. The problem was soon traced to defective paper capacitors and replacing these has prevented any further breakdowns. It’s a tribute to the 40-year old design and the robust British con­ struction that the machines still work perfectly after all these years, so long as replacement valves can be found. The Cintels are the only valve devices left at Cad­ burys. But there is hardly any part of the production line that is not supervised or mon­itored by electronics of one kind or another. Thank you J. L., for an interesting story. Its an area of electronics we seldom think about. And half your luck; I’ve always dreamed about being let loose in a chocolate factory. SC CEBus AUSTRALIA KITS CEBus Australia has opened the Circuit Cellar door to bring you a range of high quality, educational electronics kits. There are three types of kit available: an Experimenter’s Kit which includes the PCBs, manuals, any key components that are hard to find and the basic software required by the finished product. Then there is the Complete Kit which includes everything above plus the additional components required to complete the kit. Finally, there is the complete kit with Case & Power Supply. Regardless of which kit you purchase you get the same high quality solder masked and silk screened PCB and the same prime grade components. Our range of kits includes: HAL-4 4 Ch, EEG Monitor, Complete kit only ................... $356.00 Experimenter’s Kits: SmartSpooler, 256K print spooler ..................................... $214.00 IC Tester, Tests 74xx00 family ICs .................................... $233.00 Serial EPROM Programmer, For 27xxx devices ............... $214.00 Ultrasonic Ranger Board with Transducer.......................... $194.00 NB: The above prices DO NOT include sales tax. Don’t forget we also have the HCS II, Home Control System, available, Its features include: Expandible Network, Digital & Analog 1/O, X-10 Interface, Trainable IR Interface and Remote Displays. Call fax or write to us today for more information. Bankcard, Mastercard & Visa accepted. CEBus AUSTRALIA. Ph (03) 467 7194. Fax (03) 467 8422. PO Box 178, Greensborough, Vic 3087. June 1993  35