A PA-28 pilot suffered a landing gear collapse on landing following an apparent loss of electrical power.

Narrative

I went flying with our Piper Arrow Turbo IV to perform touch and go takeoffs and landings. The airplane had been returned to us after having an alternator and alternator drive replaced. I had performed four touch and go take offs and landings and was in the process of performing the fifth. After takeoff and while climbing to pattern altitude on departure I notice the GPS was not displaying. I then tried to use the radio and found it was not functioning. I then turned crosswind and then to the downwind. While on the downwind leg of the pattern I switched the transponder to 7600. When I was abeam the runway numbers I moved the gear handle to the down position; and backed the power off to 25' of manifold pressure. I flew to the 45 degree point from the runway and dropped 10 degrees (or the first notch) of flaps while I turned to the base leg. I back off the power to 17' of manifold pressure. I reached the turn to final and dropped 20 degrees of flaps. I established a stabilized descent; dropped 40 degrees of flaps and checked the gear switch to ensure it was in the down position. I wanted to touch down on the runway numbers to make the first taxi way because I wanted a clear view of the tower for light controls considering I had no radios.I was lined up on the center of the runway; backed off all power at the end of the runway; rounded out and flared. The airplane touched on the numbers and then started to turn to the right. I applied left rudder but the airplane didn't respond. At the same time the airplane sank lower and I heard the prop strike the ground and the airplane skid on the runway. The airplane did start to turn to the left and came to a stop at the 1;000 FT mark on Runway 35L. I exited the airplane and didn't touch anything. When the fire crew arrived; in the presence of the Fire Captain; I shut off the master switch; ignition switch; and the fuel selector valve.