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Spockie-Tech
Site Admin
Joined: 31 May 2004
Posts: 3160
Location: Melbourne, Australia
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Thermal Expansion.
Computers consist of *millions* of solder connections. Many of them are surface mount chips where the connections are formed automatically by painting the circuit board with solder paste, placing the cips, and then heating it until the solder melts and pulls everything into place and connects it.
This is called "Reflow" soldering - http://www.youtube.com/watch?v=5AUpN5kfiLc (The interesting bit happens at 1:25 )
Sometimes a connection isnt made properly, and since a computers circuitry ticks over like a swiss watch running in hyperdrive, the effect of a single not connected pin would be like one of said watches gears missing a tooth whilst meshing at warp 9
Putting some heat into things causes the circuit boards and metal to expand slightly, which can either make or break a connection. Sometimes heat causes the dodgy connection to press tighter together and everything is ok, sometimes it pulls it apart and things fall apart when it gets warm.
This is why any repair electronics techies bench will always have a heat gun and a can of freeze spray - it allows you to move around the circuit board heating and cooling parts of it, which localises which area causes failures when temperature cycled.
Unfortunately most computer components are of such a high connection density (any square centimeter probably contains a few hundred connections), such a low cost, and are so difficult to hand-rework becuase of the tiny solder joints, that trying to find the faulty connection and resolder it just isnt worth the time.
Usually your best bet is to use afore mentioned hair dryer and freeze spray to narrow the problem down to an individual board (motherboard, graphics, card, hard drive, whatever), and just replace that part.
Thats the most common cause anyway. similair things can sometimes happen *inside* the chips on occasion and some types of components can suffer thermal-related problems, but its the solder joints most of the time. _________________ Great minds discuss ideas. Average minds discuss events. Small minds discuss people
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Sun Jun 07, 2009 9:55 am |
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