Date : 10/02/98 7621065
SM POWER StBy
7621065
12
SUB MODULE
762106S
TECHNICAL DESCRIPTION SWITCHED MODE POWER SUPPLY (7621065).
Introduction.
On the main board of this module we find the generation of all stable voltages ,
we mean voltages independent on the line frequency, and the vaHTHD
voltage (referred to as the second SMPS).
This second SMPS is linked via the subunit with the horizontal deflection board
as the +HTHD voltage (horizontal scan voltage) is linearly proportional with the
line frequency.
Because the second SMPS utilizes the rectified voltage from the winding P22-
P24, this SMPS totally depends on the first one' , or in other words, if the first
SMPS is down , the second one follows .
The ON/OFF voltage delivered by the controller board can stop or start up these
Switched Mode Power Supplies.
The subunit comprises the DC-fan control, the regulation circuit for the +HTHD,
its Under- and Over voltage protection circuits, the +17volts drop protection and
the stand-by power supply.
Generation of the line fre-
quency independent volt-
ages.
The mains voltage is rectified on the Mains Filter unit (76 2114) and the +300 volts
is now the supply voltage for the power switches Q100 and Q101 on the main board.
We assume that the thyristor TIC106C is conducting (its gate is not clamped at
ground level, see later).
The positive halfwave of the mains voltage (START) charges C102 via D104 . The
gate of the thyristor is set at 11 volts with the zener Z100 through R101 from the
+300volts.
As soon as the capacitor voltage of C102 reaches approximately 12 volts, the IC
can start up by driving the base of the power switch.
The diode D104 stops conducting as its anode is at about (11 + 0.6) volts.
The thyristor gets blocked as well, because its cathode equals the gate voltage.
In the meantime the IC102 has started up and the voltage at pin 9 receives its supply
voltage now from the winding 24-22 of the T2 transformer via D109.
The push-pull outputs, pins 7 and 8, drive the Q101 power switch and during the off
time of the latter the accumulated energy in the primary winding is transferred to
the secondary capacitors via the rectifying diodes (flyback principle).
The feedback winding 21-22 provides two informations for the control IC :
Firstly
, the waveform is sent to pin 2 where the
zero passages
are detected,
useful to drive the power switch on at the exact moment.
The base drive is delayed until the energy in the transformer has been com-
Technical description
Summary of Contents for GRAPHICS 1209S
Page 4: ...BARCO PROJECTION SYSTEMS GRAPHICS 1209S 90 00972 230V AC 90 00977 120V AC SAFETY NOTICE...
Page 9: ...BARCO PROJECTION SYSTEMS GRAPHICS 1209S 90 00972 230V AC 90 00977 120V AC GENERAL INFORMATION...
Page 28: ...BARCO PROJECTION SYSTEMS GRAPHICS 1209S 90 00972 230V AC 90 00977 120V AC SERVICE SHEETS...
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Page 307: ...Date 18 06 96 R762284 Power mains input module R762284 1 SERVICE SHEET Rev 01...
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Page 354: ...Date 10 02 98 R761781 IR Receiver module R761781 1 SERVICE SHEET IRRECEPTION IRRECEPTION...
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