Friday, April 28, 2006

A classic engineering solution... 

“If this was an old-fashioned telephone” I said, having just been deafened by a severe crackling sound in my ear “I’d just thump the handset on the desk”. I could almost see the smile of recognition on the face of my engineer friend at the other end of the line, of an age to be well acquainted with this problem and its cure. Although the solution might seem to owe its source to a short temper, it was entirely scientific - once upon a time, telephone microphones used a mechanism containing carbon granules which was rather susceptible to an attack of the crackles, a state which could be remedied by a good sharp shake up of the aforementioned granules.

The first TV set I remember was like that too; it suffered the visual equivalent of those crackles. Hands up all those who remember the days when TV sets had a row of little knobs hidden around the side somewhere labelled “vertical hold”, “horizontal hold” and such like? On those occasions when the picture was replaced by jagged black and white lines across the screen and deft (or more likely, random) twiddling of those knobs failed to restore it, a good sound thump on the top of the cabinet would often do the trick.

Modern mechanisms may be more delicate, but the same “thump it” principle seems to work still. The CD player in my hi-fi (well okay, mid-fi) system packed up a couple of days ago. “No disc” the display lied, no matter what disc I put in. Nothing to lose I thought, and took the top off. Loaded a CD in the drawer and watched – nothing. Stationary CD; no sign of any attempt to spin. A broken wire? Broken drive gear? Broken motor? I took the CD out and span the mechanism with my fingers – it seemed free enough. Put the CD back and – hey presto! – this time it span and played. Something must have got stuck somewhere and just needed a nudge to free it up.

It reminds me of a story I read somewhere. Apocryphal, perhaps, but it illustrates a point. A ship - in the days of steam, I think - was having engine trouble. Docked in port, an expert was called in to fix it. He had just two tools – a rod, which he used a bit like a stethoscope to listen to the pulse of the engine, and a hammer. He spent a while in the engine room, just listening here and there, and then tapped a valve once with the hammer. When he sent in his bill for $1000 the company questioned why he charged so much when he was only in the engine room for such a short time, and demanded an itemised bill. This is what it said: “For tapping with hammer: $1. For knowing where to tap, $999”.

A nudge, a thump, a sharp tap – shake up the system a bit. Never fails. Now, where exactly do I bang my head to get it working properly again? Or, for that matter, my heart?

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