Repair Guru

Nothing on the bench is scripted A machine that comes in is a real circuit, built out of real components, with something genuinely wrong with one of them. There is no hidden answer and no list of steps. There is a resistor that has drifted, a capacitor that has gone leaky, a solder joint that lets go once the board is warm — and the reading your meter gives you is what that circuit would actually do. Twenty-six machines, from a desk lamp to a home organ. Twenty-seven kinds of component. Five hundred and fifteen different things that can be wrong, and every one of them can be found and fixed.Halve the chain, then halve what is left Every machine is a chain of blocks with a test point between each pair. Full signal at one point and nothing at the next means the fault is in the block between them. Probe in the middle rather than at the end, and every measurement halves what is left to search. That is the whole method, and the game never does it for you.Most faults are shy A dry joint is perfect cold and lets go at eighty per cent warmth. A worn…