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Publisher & Editor-in-Chief Leo Simpson, B.Bus. Editor Greg Swain, B.Sc.(Hons.) PUBLISHER'S LETTER Technical Staff John Clarke, B.E.(Elec.) Robert Flynn Darren Yates, B.Sc. Reader Services Ann Jenkinson Sharon Macdonald Sales & Marketing Mgr. Sharon Lightner Phone (02) 979 5644 Mobile phone (018) 28 5532 Regular Contributors Brendan Akhurst Garry Cratt, VK2YBX Marque Crozman, VK2:ZLZ John Hill Jim Lawler, MTETIA Bryan Maher, M.E., B.Sc. Jim Yalden, VK2YGY Bob Young Photography Stuart Bryce Editorial Advisory Panel Philip Watson, MIREE, VK2ZPW Norman Marks Steve Payor, B.Sc., B.E. SILICON CHIP is published 12 times a year by Silicon Chip Publications Pty Ltd. A.C.N. 003 205 490. All material copyright©. No part of this publication may be reproduced without the written consent of the publisher. Printing: Magazine Printers Pty Ltd, Alexandria, NSW; Macquarie Print, Dubbo, NSW. Distribution: Network Distribution Company. Subscription rates: $42 per year in Australia. For overseas rates, see the subscription page in this issue. Liability: Devices or circuits described in SILICON CHIP may be covered by patents. SILICON CHIP disclaims any liability for the infringement of such patents by the manufacturing or selling of any such equipment. Editorial & advertising offices: Unit 1a/77-79 Bassett Street, Mona Vale, NSW 2103. Postal address: PO Box 139, Collaroy Beach, NSW 2097. Phone (02) 979 5644. Fax (02) 979 6503. ISSN 1030-2662 2 SILICON CHIP Computer monitor reliability leaves a lot to he desired Over the last 20 years or so, the reliability of consumer electronics appliances has become almost legendary. As a result, many TV servicemen have either retired or gone out of business. But there is one area where the overall reliability leaves a great deal to be desired and this is in regard to video monitors for personal computers. While you would think that the enormous complexity of the new motherboards or hard disc drives would make them suspect, it is the computer monitor which, more often than not, is the first item to fail. This is despite the fact that computer monitors are much simpler than the average colour TV set and the · deflection circuitry is probably not working as hard. Yet computer monitors fail often, usually in the power supply or deflection circuitry- actually there is not much else to fail. This is not a new phenomenon by any means and in the days when monochrome monitors were standard, it was usually cheaper and much more convenient to buy a new monitor than to repair a failed unit. These days though, VGA and large screen monitors cannot be simply discarded when they fail;. they must be repaired. When that time arrives, be prepared for a large bill. Many authorised service centres only do board exchange and the cost can range from a few hundred dollars to six hundred or more. Even though the fault may be relatively simple to fix, the companies concerned often have a deliberate policy of doing board-level repairs only and the consumer really does pay through the nose. In one very well-known brand, a resistor in the starting circuit of a monitor's switchmode power supply regularly fails. The obvious and easy cure is to replace that resistor with one of a higher rating and yet the company concerned has never made any move to change it. In effect, you pay over $200 for a burnt out five-cent resistor. The situation is made even more difficult because computer monitors are not supplied with a circuit diagram and they always use Japanese or Asian parts which are often difficult to_obtain. Nor will most importers even deign to sell a service manual or circuit diagram. And if the company concerned goes out of business you are really on your own. It would be easy to conclude that there is a certain amount of unfair trading going on in this field. That means that consumers should try to at least obtain a circuit and preferably a service manual when they purchase their monitor. I say that, knowing just how difficult it is in practice. It also leaves the way open for importers to establish a more enlightened policy on this often unhappy aspect of computing - their customers will love them for it. Leo Simpson