Servos not serving

[queenidog]

I have two servos running off a 16F887 with no issues. Both toggle back and forth at roughly a 90 degree angle, in about 2 seconds.

I changed commands for a 12F675, mounted same on a prototype board with hefty 5 volt power supply/converter. With one servo connected (to GP1), everything is fine. With TWO connected, it's as if the time period was extended by a factor of 100: each servo does a little "tick" in about 1 second: at that rate, it will take 10 minutes or more to swing 90 degrees. Not only that but there is chattering where they can suddenly move 10 degrees. If I swap servos, same thing occurs. There is NO voltage drop on the MCU or servos when #2 is added. There is no NOISE on the power lines. Different servos create the same problem.

On a scope I cannot see any change whatsoever. The pulses are there, varying 1.0 to about 1.5 mS, and the overall period is 20 mS. (It's a little lower, frequency is about 65 Hz instead of 50 Hz). The program is attached for the 12F675. Even when the servos are chattering, the waveforms look okay.

Am I missing something? Is this a software or a hardware (ie MCU) problem?