Crown XLS 1000 Series, Руководство по обслуживанию

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U102 has programmable dead-time which can be changed by the APM through a
programming current drive into Q107-108. U102 provides current limit protection for the
MOSFETs. R153-154 set the negative current limit and R158-159 set the positive current
limit. U102 provides under-voltage protection for the MOSFETs to protect against low
gate drive voltage.
U102 is supplied 12V for the low side drive from the gate supply powered from the
LVAC winding on the transformer and is regulated to 12V by U3.
The output PWM from the MOSFETs is filtered by L101 and a series of capacitors as
shown on the schematic. Further reduction of the switching frequency ripple is achieved
by the 384KHz trap consisting of C147/173 and L102. L102 is tuned for minimum ripple
at the output terminals.
From the output filter the signal passes through a relay (K101) before going to the output
terminals. The relay is controlled by the APM and is enabled after the power on self test
has passed.
Ruby control circuits.
The Ruby IC is placed in slave mode and in order for Ruby to function it must be
provided a clock signal on pins 5 and 6. This is a 384KHz signal that is provided by the
APM. It must be powered by 5VDC at pins 29,30,38 and 59.
Pins 12 and 13 provide I2C communications with the APM.
The Ruby IC has several ADC channels that the APM reads and uses to control the
operation of the amplifier. These inputs are all referenced to the VREFSAR internal
voltage reference which is buffered by U2A.
RT1 is a temperature sensor (NTC) placed under the Secondary Diode heatsink and is
connected to pin 19. This temperature is then read by the APM and used to limit the
temperature in case of a fault.
RT101 is a temperature sensor (NTC) placed under the Channel 1 heatsink and is
connected to pin 53. This temperature is then read by the APM and used to limit the
temperature in case of a fault.
RT201 is a temperature sensor (NTC) placed under the Channel 2 heatsink and is
connected to pin 52. This temperature is then read by the APM and used to limit the
temperature in case of a fault.
As mentioned before a scaled version of the +/-Vcc levels are connected to pins 20 and
21. These signals can be queried by the APM and also will shut down the PWM signal in
case of an overvoltage on the Vcc’s.