Philips 7629 Service Manual page 79

Degaussing
When the set is switched on, the degaussing relay 1515 is immediately activated as
transistor 7580 is conducting. Due to the RC-time of R3580 and C2580, it will last about
3 to 4 seconds before transistor 7580 is switched off.
Basic IC Functionality
For a clear understanding of the Quasi-Resonant behavior, it is possible to explain it by
a simplified circuit diagram (see Figure below). In this circuit diagram, the secondary
side is transferred to the primary side and the transformer is replaced by an inductance
L .C is the total drain capacitance including the resonance capacitor C
P D
output capacitor C
transformer. The turns ratio of the transformer is represented by n (N
Figure:
of the MOSFET and the winding capacitance C
OSS
, parasitic
R
of the
W
/N ).
P S