"...I telling you Teal'c, if we don't find our way out of this soon, I'm going to loose it. ... Lose it, it means go crazy, nuts, insane, bonzo, no longer in possession of one's facilities, three fries short of a happy meal, WACKO!"
-Colonel Jack O'Neill, in Window of Opportunity.
The "Time loop machine" was a device of Ancient design built on P4X-639 which continually loops time every ten hours.
Overview
The control pedestal of the machine.
The device is powered by static energy in the ionized atmosphere, attributed to the increased solar activity from the resident Star. It is controlled by an advanced panel of cubed "buttons" which emit a complex combination, raising and lowering at various levels, allowing the process to proceed and the static energy to mount. Enormous beams of energy would be fired at the Stargate to cause a time loop.
History
The Ancient colony was faced with an intergalactic plague which swept the galaxy. Some of the Ancients were determined to beat the plague by attempting to travel in time, so they constructed the loop machine. However, time was looping every ten hours, rather than years. They attempted to increase the loop, but no matter what they did, they couldn't figure out a solution and they all died (apart from those who escaped to the Pegasus Galaxy).
Several millenia later, a scientist named Malakai discovered the device and attempted to finish what the Ancients started in order to succeed, because his wife died and he wanted to return to see her again. However, the time loop not only affected P4X-639, but thirteen other planets relatively close, including Alaris and Earth as well. Through coersion, Malakai shut down the device and left it behind. (SG1: "Window of Opportunity")
After they moved to the Pegasus Galaxy, a scientist named Janus developed a successful time machine.