FEATURES The DB-5500 COMPUTER UPS TRAINERS is designed to instruct service technicians in the operation, theory, servicing, problem diagnosis and repair of the key devices & components used in Information Technology. The trainer is based upon computers and components which have been modified to facilitate training and have a special electronic fault insertion system. The unit consists of one drive that shows all key internal components and functions.   SPECIFICATIONS FEATURES OF THE SYSTEM 1) Based on highly reliable microchip PIC micro® micro-controller. 2) MOSFET based power stage, with PWM AC output. 3) Mains to backup mode changeover time less than 9mSec. 4) Backup mode protected against overload, short circuit, reverse phase and unbalanced MOSFET drive. 5) Line synchronized change over from mains to backup and back. 6) Over current of MOSFET's protected within micro seconds. 7) Three step AVR with input range 140V to 280V AC. and output range 200-245V AC. 8) MOSFET based PWM battery charger. 9) Automatic low battery warning and cut off. BLOCK & TROUBLESHOOTING 1) Backup mode failure 2) Mains failure 3) Output failure 4) Battery failure 5) Buzzer failure 6) Mains indicator failure 7) Output indicator failure 8) INV. indicator failure 9) Battery reference voltage failure 10) Complete UPS circuit failure (backup & mains both mode failure)