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Section D — Theory and design (4 × 4 = 16 marks) 11. Explain why front-panel cables are often keyed and why manufacturers still include single-pin headers for small switches/LEDs rather than combined multi-pin modules. (4 marks) 12. Discuss ESD precautions when servicing front-panel connectors and why they matter. Provide two practical steps to reduce ESD risk. (4 marks) 13. Describe how an inverted LED polarity connection would appear at power-up and how to correct it without replacing the LED. (4 marks) 14. For a revision-labeled board (e.g., Rev 1.00 → Rev 1.01), list three typical reasons a manufacturer issues a minor revision for a front-panel PCB. (4 marks)