As consumer electronics becomes more complex and compact, test equipment and service aids are evolving to match. Fault diagnosis and solder rework on thinscreen TVs are facilitated by specially designed workshop tools. Here are some good value for money ones.
One of the problems with surface-mount PC board assemblies is the difficulty of making contact with ordinary test probes: clips and conventional prods are far from ideal here. Available now from CHS (www.charleshyde.co.uk) is a ‘tweezermeter’ which can be applied across most SMD components with one hand. The 11mm-high LCD display has a maximum readout of 5,999 and can indicate resistance up to 60MΩ, capacitance up to 60mF, and check continuity of fuses and print runs, also diodes. It has auto recognition of the function required, and runs from a couple of internal 15V button cells. Made by PeakTech, it weighs 65g, measures 181×35×20mm, and costs a mere £28.50 to account holders under part no. 5425727. At the other end of the scale (and for very rich service engineers.) CPC at www.cpc.co.uk offers a similar, more accurate tweezer device, with ranges down to 0.1Ω and 10pF, also an inductance measuring facility of 1µH to 1H, at £206. Its order number is IN05319.
Tubes used to mean cathode rays; now the tubes we deal with are fluorescent ones mounted behind LCD screens and their diffusers. In many LCD TV designs a safety shut-down device comes into operation when a tube is faulty, making it difficult to get an assured diagnosis. To the rescue comes the HR-Diemen backlight tester, a generator of high test voltages for all types of FL tubes. CC, cold cathode types are the most common, while HC – hot cathode – tubes are more efficient, used in low-energy TVs. EE (external electrode) variants have high lumen efficiency and run very cool. This tester, part no. 9091257 can cope with all of them. It runs from a 12V power unit (supplied separately at low cost) and has LED indications for power and tube connection. It costs just £66.
Returning now to the servicing of SMD-mounting printed-circuit boards, once having made a diagnosis the faulty component must be removed and replaced, and that can be an exacting and challenging job, especially with multi-connected and very tiny devices. A rework station is required for this, and they can be very expensive, running to four figures when made by well-known ‘first league’ manufacturers. Of late, however, they have become available from Chinese makers at more down-to-earth prices, and a good example here is the Duratool model, available on part no. SD01139 from CPC at around £62. It’s a hot air type with temperature adjustable from 150° to 500°C. Control is by a closed loop K-thermocouple device, while the pump is a diaphragm type with 24litres/min capacity. Ten different types and sizes of nozzles are available at £3.50 each, covering a wide range of device shapes.
For more modest requirements, and perhaps for use alongside a full-blown rework outfit, a temperature-controlled soldering iron is useful, amenable to both leaded and unleaded solder assemblies. Again the price of these tools has come down in some quarters, though the very cheapest are not suitable for continuous use in a professional setting. At present Grandata (www.grandata.co.uk) has an excellent special offer going, in which it bundles together a temperature-adjustable/digital readout 48W soldering-iron station and a wide-ranging digital multimeter – with capacitance and audio frequency measuring capability – for £50: the package can be ordered as TOOLPACK1, saving money on the separate list prices of these two useful instruments. All the prices quoted here are net to trade account holders, subject to change, and do not include VAT.
I believe that investment in workshop equipment, especially such modest investment as required by the equipment described here, is viable even in these hard times. People now are pleased to find repair shops that offer local expertise without taking large three-figure sums up front like the multiples’ service arms and the manufacturers’ appointed service agents. Most punters are now also ready to pay an equitable price for a repair where it’s viable at all, and appreciate the faster turn-round that independent firms can often achieve. Still I wish that there was more servicing work going.