Date : 10/02/98 7621065
SM POWER StBy
7621065
14
SUB MODULE
762106S
Under voltage protection.
The stabilized zener voltage with Z8 is used as reference voltage for the comparator
393, pin 6. Now, the other pin 5 is the +HTHD voltage.
If the pin 5 drops below the reference voltage, the output switches low, and the
transistor Q8 saturates, pulling again pin 2 of IC5 low.
Protection against too low +17 volts.
If, for some reasons, the +17 volts (and all the other voltages as well) are, even
temporarily, too low, it is then advised to shut down the +HTHD voltage (coming from
the other SMPS).
Pin 6 is preadjusted, ex factory, at approx. 14 volts with P1
This happens with the comparator in IC3 and its output pin 7 saturates again Q8.
Temporary shut down at switching.
The "DEFL" info from the HOR DEFL board can switch on Q10 via Q11 and also
pull down pin 2 of IC5. This is necessary the moment the relays switch the two
windings of the scan coils from series to parallel or vice versa.
Stand-by / ON-OFF switch-
ing.
An oscillator is built up around Q1/Q2 and the transformer T1.
Q1 gets its base current via R3. The collector current of the latter flows in the winding
1-3 and induces a voltage in the winding 5-4 ' encouraging' the base current.
As soon the emitter voltage of Q1 can drive the Q2 and saturate it, this transistor
clamps the base of Q1 at ground level and cuts off Q1. The cycle starts all-over
again.
Two opposite polarity SB voltages (+/- 9 volts) are available at the secondary side.
a) Stand-by mode (OFF).
The voltage at contact 3 of the J4 connector (OFF) is in this case high and this
means for the optocoupler IC1 that the phototransistor is not conducting.
Q3 is thus saturated as R6 can provide the required base-emitter current.
The collector of Q3 is low .Furthermore, pin 5 of IC102 is below its "active level"
via the diode D105 disabling, the drive output.
As a conclusion, only the standby vo/- 9 SB voltages are available.
b) Operational mode (ON).
The I/O block of the controller board ( collector of a transistor) pulls now contact 3
of J4 at a low level to light the LED in the opto-coupler IC1.
Now, the phototransistor of the latter is saturated and brings the base of Q3 at nearly
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 157: ...Date 10 02 98 762457 Deflection Switching Module 762457 1 SERVICE SHEET...
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Page 166: ...Date 10 02 98 R7621127 Sync Vertical Deflection R7621127 1 SERVICE SHEET...
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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 339: ...Date 10 02 98 R7627591 Frame cpl R7627591 1 SERVICE SHEET R806430...
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Page 354: ...Date 10 02 98 R761781 IR Receiver module R761781 1 SERVICE SHEET IRRECEPTION IRRECEPTION...
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Page 359: ...Date 10 02 98 R762510 IR RS 232 Communication module 1 R762510 SERVICE SHEET...
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