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15. Lamp Power Supply R7633705
Low Voltage Power Supply.
This power supply (SMPS) generates the stand-by (remains active in the operational mode) voltages for the low power circuits on
this module, the boost voltage circuits, and the fans.
Lamp Power Supply Secondary.
This board contains the transformer T300 of the HF DC/DC CONVERTER. This transforms the HF square wave input voltage (at
200kHz) to a lower value, at the secondary side, where D301 and D302 rectify the pulses to obtain the lamp voltage at the output.
Lamp_voltage_sense information.
The I330 sense the lamp voltage (signal VS is 0.1V for 1V on the lamp).
Lamp_current_sense information.
Isolating OPAMP and DC current to voltage converter of the lamp_current_sense information.
With these two information lines, the lamp voltage and current are measured and used by the controller IC to regulate the power of
the lamp.
Boost voltage Generator.
The lamp needs an arcing or ignition voltage to start up. This is an AC voltage that can reach 40kV with a frequency of 3MHz.
The SPG (Start Pulse Generator) employs the lamp voltage as supply voltage (see SPG). This lamp voltage is boosted up during
the start to 92V with a "boost circuit".
From the moment the lamp is ignited, the boost circuit is switched off by the microprocessor.
Temperature Sensors
The temperature of the heatsinks of the secondary output diode (D302) is measured with an NTC resistor and the info is handled by
the microprocessor on the R7632103.
Furthermore, a temperature sensor is incorporated in the T300 transformer as a protection element against overheating of the latter.
Led indications
The status of the smps is shown by the yellow LED (LVPS OK).
The status of the LPS is shown by the green LED (LAMP ON), This led is ON when the DC/DC converter delivers power to the lamp.
Important Note:
The secondary outputs are separated from the mains by base isolation. It is strongly forbidden to connect the device or a module
to the mains without secure grounding.
15.5.3 EMC Filter - Rush-in Current Limit - Mains Rectifier.
Description
The mains input is connected via the connectors J20 and J21.
Fuse F100 is designed to blow as a result of over current brought about by a possible defect in the module. Thereby the projector
can also operate on a lower power with other lamp supply modules (redundancy).
The mains voltage passes first a double EMC filter C100/L100 and C101/L101. Resistors R102 to R104 limit the inrush current
loading the big smoothening capacitors on the other board.
To avoid unnecessary heating, these resistors are shorted with RL1 which is supplied from the ++15VM generated by the standby
SMPS on this board. The diode bridge D103 rectifies the AC voltage.
A relative small smoothening capacitor of 1µF (on the other board) is sufficient at this stage, because a PFC circuit follows.
By means of two diodes D101 and D102, the shape of the AC waveform is checked and used by the PFC controller IC on the other
board R7632105 to modulate the current.
15.5.4 On-board SMPS.
Description
This "flyback SMPS" is built around I200, TOP223Y, performing all necessary functions for driving the primary of the transformer
T200 and the stabilization of the output voltages.
The input voltage is the +380VM via the connector J608, pin 8, from the other PFC board R7632105. The fuse F200 interrupts this
connection in case of a fault (short) in the SMPS.
The transformer delivers one primary and three secondary voltages :
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R5976820 SLM R12+ PERFORMER 08/03/2005
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