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56 The PCB Design Magazine • July 2014 2. Data I/O programmers read, verify and store data in programmable logic devices, such as PROMs, microprocessors and memory de- vices. A master database of all programmable devices is stored for current and future repairs. 3. Using Hot air IC installation & removal systems, surface mount ICs can be subjected to temperature-controlled hot air to reflow sol- der. A vacuum pickup tool is used to remove or install the chip with the help of a magnifying CCD camera. 4. Signature analysis is the primary diagnos- tic tool for PCB repair activity. It works by ap- plying a current-limited AC signal across two points of a semiconductor junction. The cur- rent flow causes a vertical deflection of the CRT trace, while the applied voltage causes a hori- zontal deflection. Together, they form a unique V/I signature that represents the overall health of the junction under test. Analyzing the deflec- tion signature tells us whether the component is good, bad or marginal. Many units also have the internal ability to fire gate-triggered devices while viewing the V/I curves. 5. Oscilloscopes of various bandwidth, both analog and digital, are used to analyze voltage waveforms under power. 6. Function generations are used to simulate square, sinusoidal or triangle wave input and trigger signals. 7. Digital volt meters (DVMs) can measure voltages from 3.5 digits down to 6.5 digit preci- sion at the selected measurement range. 8. Sencore cap & inductance meters are used to analyze capacitors for capacitance, equiva- lent series resistance (ESR), dielectric leakage and frequency response. Inductance meters are used for measuring similar attributes in coils. 9. Power supply load boxes are dynamic load banks for testing power supplies' capaci- ties, hold-up time, and spike sensitivity. 10. Calibrators are reference systems trace- able back to NIST standards for final adjustment of temperature, flow and pressure related prod- ucts. 11. Mings are hand-held testers for identify- ing and checking various integrated circuits. 12. System or simulation testers provide a means to test assemblies from the connectors to determine entire functionality. Furthermore, all equipment should be iden- tified as either used for diagnostic work or for fi- nal repair (calibrated). All calibrated equipment should be on a scheduled gage program. III. Economies of Scale The best repair, rework, and overhaul op- tions at the lowest price points are only sustain- able if an ISP is highly scalable. For example, larger repair shops can of- fer more agility by leveraging their inventory of new and refurbished circuit board assembly parts. This is especially important as it relates to emergency/rush repair services when customers are experiencing production downtime. In addition to cost-effectively replacing de- fective circuit boards components with new and/or more reliable parts, plant managers, owners and operators want a full-service part- ner that can improve their equipment perfor- mance and operating efficiency as a whole. Most repair shops, however, do not have the manpower, experience, and technology neces- sary to provide value-added PCB redesign and manufacturing services, for example—these are simply cost-prohibitive for small and medium- sized repair facilities. Bottom Line When your circuit board repair project is complete, the remanufactured, like-new con- dition board(s) should always meet the same industry specifications for performance as new PCBs. If you found a quality shop, you should expect that the parts will easily exceed the ex- pected lifetime of the original board. And when it's all said and done, choosing the right PCBA repair provider can save you up to 70% compared to the cost of buying replace- ment PCBs from the OEM. PCBDESIgN article CHOOSINg THE RIgHT PCBA REPAIR SHOP continues ronald D. Fukui is the director of engineering and technology for the repair services Division of Psi repair services. he is a former president and majority owner of FAsT inc., a company that provides repair services to the industrial equipment market.