Percussive maintenance - Wiki

Percussive maintenance is also known as percussion therapy or a technical tap. It is a term used to describe the malediction of an ill-behaved device to make it work, that is to say, swear at it and hit it. The origins and practice of the term are unknown, although some suggest the act became commonplace with the introduction of vacuum tube electronics.

Modern applications

The technical tap still has applications today.

Transformers

Step-down transformers, especially domestic ones used in computer PSUs and televisions with speakers often develop a high-pitched whine over time from old or faulty capacitors. This can often sit on the borderline of human hearing and so can be difficult to detect or isolate for those not used to it.

If a step-down transformer develops a high-pitched whine, the annoying sound can be silenced by a sharp tap to the casing surrounding it, as close as possible to the faulty capacitor (if you can find it). To avoid damaging sensitive components, capacitors and diodes should never be directly asserted with percussive maintenance; a warning generally suffices. This is not a permanent solution and the sound will likely come back some time, possibly louder, but for many people it is often a practical method to restore silence.

Vehicles

The technical tap is also used by many automobile drivers to restore the function of misbehaving dashboard and console back lighting, it is easier and quicker than getting a soldering iron. Furthermore, in the current generation of after market head units, the detachable faceplates rely on gold plate contacts to bridge the connections. Gold is very soft, so this coating tends to wear off over time, especially if the faceplate is repeatedly removed and replaced. This can result in the faceplate sometimes losing connection and dimming, if not going outright dead. A light technical tap is often the best way to restore function to such a unit.

Another technical tap is used on a faulty starter motor to get it to turn over. If the solenoid sticks or the brushes are worn, they make intermittent contact, causing the starter not to function when the key is turned. Often this is done with one person turning the ignition key while another taps the starter motor.

Computers

Hard drives, especially portable ones, can become stuck from stiction between the heads and platters. A technical tap as the drive is trying to spin up can get them moving and working again, but one should immediately back it up as the procedure can cause a head crash later.

The motion detection sensors in a Nintendo Wii Remote can become stuck. Even customer support reportedly suggests a good technical tap when all else fails. Turn the remote button-side down in your palm, and tap it loudly, but not so hard as to damage it.

Lane's Principle

Lane's Principle is a scientific theorem which refers to the Technical Tap. The Principle states: "There is no problem which cannot be solved by suitable application of blunt force." The identity of the author is unknown, but the saying was included in the MIT SIPB "fortune" program, which dispensed tech-related quotes on demand as early as 1989.

It has yet to be discovered by science what is suitable.

Famous taps in history

* In a 1953 live television broadcast, at the coronation of Queen Elizabeth II, the cameraman inside Westminster Abbey was having trouble with getting his camera to work. With only seconds to spare until the transmission started, he angrily kicked the camera, switching it on and providing pictures of the coronation.
* In 1969 during the Apollo 12 mission, Pete Conrad was working on a piece of equipment called the ALSEP. He was trying to remove its power source from its case so that he could insert it into the device but was having difficulty. Alan Bean suggested he hit it with a hammer. Conrad resisted at first but eventually gave it a tap. It worked, leading Bean to quip, "Don't come to the moon without a hammer."
* In 1973 during the first Skylab mission, NASA wanted the astronauts to try reactivating a non-working module in the power system. The astronauts' instructions included the observation that "Pre-Flight history has indicated past relay hang-ups which have been freed by mechanically shocking the relay. Recommended procedure is to strike the CBRM housing at the point indicated below [on the accompanying schematic]. Tests indicate that you cannot hit the CBRM hard enough to damage it." The astronaut who performed the operation was well acquainted with the procedure—Pete Conrad.
* In December 2006, NASA astronauts Robert "Beamer" Curbeam and Sunita "Suni" Williams spent a generous amount of time shaking and pushing a stubborn solar panel into its case so they could move it to a different location on the International Space Station.

References

1. ^ GeekDad, Wired Blog Network, Crazy (real-life) Wii Remote tech-support call...
2. ^ - Apollo 12 Lunar Surface Journal : ALSEP Off-load : Corrected Transcript and Commentary
3. ^ SPACE.com - Solar Array Shake: Astronauts Rewire ISS, Fourth Spacewalk Set

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