Percussive maintenance

From Wikipedia, the free encyclopedia

This article does not cite any references or sources. (April 2008)
Please help improve this article by adding citations to reliable sources. Unverifiable material may be challenged and removed.

Percussive maintenance or percussion therapy also known as a technical tap, is a term used to describe hitting a malfunctioning device in order to make it work correctly again.

This term's origins are unknown.

1 Famous historical taps
2 Famous taps from fiction
3 Modern day applications
4 Lane's Principle
5 References

[edit] Famous historical taps

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 Conrad to quip, "Never come to the moon without a hammer."

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 of 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^[1].

[edit] Famous taps from fiction

Fonzie from Happy Days was famous for using a technical tap on the jukebox at Arnold's diner, an act which has been parodied on several TV shows including Family Guy, Veronica Mars and Scrubs.
Michael J. Fox's character in Back to the Future used a technical tap on the time machine during the climactic power failure just before going back to the future.
Harrison Ford's Han Solo from Star Wars Episode V: The Empire Strikes Back helped the Millennium Falcon restart with a technical tap.
Colm Meaney's Miles O'Brien from Star Trek: Deep Space Nine was seen fixing a Cardassian Transporter with a kick in the pilot episode Emissary
The Doctor is often seen applying "percussive maintenance" to the aging TARDIS in Doctor Who. In the episode "State of Decay", he fixes a monitor with a technical tap, and when that works he remarks that that proves that it's Earth technology. He has been seen operating certain components of the console with a small mallet.
Lev Andropov from Armageddon (1998 film) restarted the thrusters of a space shuttle using a technical tap, remarking "This is how we fix problem in Russian Space Station!"
In the anime Cowboy Bebop, Spike Spiegel frequently taps, hits and kicks appliances such as the television in order to get them to work, to varying effect. In one episode, after wrecking a rare Betamax cassette player by striking it too hard, he notes "My ship works when I kick it."

[edit] Modern day applications

The technical tap still has its applications today, notably in silencing faulty step-down transformers. Step down transformers, especially household examples such as those found in a computer's PSU^[2] or in a television's in-built speakers^[3] often develop an irritating high-pitched whine over time due to old or faulty capacitors. This can often sit on the borderline of the human audible spectrum and thus can be difficult to detect or isolate for those unaccustomed to this problem.

In cases where a step-down transformer develops a high-pitched whine, the often annoying sound can be silenced by a sharp tap to the casing around the transformer itself, as close as possible to the faulty capacitor if it can be located. As to avoid damaging sensitive components inside the transformer itself, capacitors and diodes should never be directly struck themselves. This is not a permanent solution and the sound will likely come back with time, possibly with greater severity, however for a great many it is often the only undertakable method to restore much-needed silence to a work area or lounge room.

The technical tap has also been utilized by a great many automobile drivers to resume functionality to misbehaving dashboard and console back lighting, presumably caused by loose solder. Furthermore, in the current generation of after market head units, the detachable face plates rely on gold plated contacts to bridge the connection between the face plate and the unit itself. This gold coating tends to wear off over time, especially if the face plate is repeatedly removed and replaced, often resulting in the face plate periodically losing connection and dimming if not going dead outright. A light technical tap is often the best way to resume functionality to such a head unit.

Hard drives, especially of the portable kind, can become stuck due to stiction between the heads and platter(s). Applying a suitable shock as the drive is trying to spin up can un-stick the heads and get it working again, but it is highly advisable to immediately back up the contents as the procedure can cause head crashes.

The motion detection sensors for Nintendo Wii Remote can become stuck. Applying a technical tap on the remote is a solution that even customer support reportedly suggests^[4] when all else fails. To solve this problem, turn the remote button-side down in your palm, and smack it loudly, but not so hard as to damage the controller.

[edit] Lane's Principle

Lane's Principle is a fictitious 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 dispenses humorous tech-related quote on demand, as early as 1989.