ASP STERRAD 100, Service Manual

Page: 180 / 309

The firmware is programmed to detect RF-system failures at three levels.
Upon entering the plasma stage, the controller monitors the pressure in
the chamber and controls the throttle valve to keep the pressure at 500
±25 mTorr. The system waits until the pressure is at 525 mTorr. If the
pressure in the chamber is not down to 525 mTorr in 3 minutes, from
the start of plasma stage, the process aborts, and prompts the user that
there is insufficient vacuum for plasma. At 525 mTorr the controller
turns on the RF power supply and after 700 milliseconds turns on the
RF amplifier to light plasma. The RF delivery power is monitored by the
controller, and the cycle is canceled according to the following criteria:
F
If delivery power is under 100 watts.
F
If delivery power is between 100 and 200 watts.
F
If delivery power is not at least 365 watts, but is greater than 200
watts, after 15 seconds, the system turns off the RF-amplifier and
power supply then turns it back on (RESET) to try again. The system
keeps trying at 15 second intervals for 2 minutes and then stops.
If any of the above situations occur, appropriate error messages are
generated. See the System Messages section or look up RF using Find+
to view the RF related error messages.
Figure 10-1. RF Subsystem
RF Theory of Operation Radio Frequency (RF) Subsystem
ASP Service Guide rev. D STERRAD® 100 Sterilizer 10-3