Samsung DVD-R130, Руководство по обслуживанию

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Circuit Operating Descriptions
13-2 Samsung Electronics
0
Vswitch
dt
Toff
t
Inverted power
by leakage
inductance
Fig. 13-2
1) Prevent residual high voltage at the terminals of
switch during switch off/Suppress noise.
High inverted power occurs at switch off,
because of the 1st winding of transformer :
(V=-L1 xdi/dt. L1 : Leakage Induction)
A very high residual voltage exist on both terminals
of PQQX1 because dt is a very short.
2) SNUBBER circuit protects PQQX1 from damage
through leakage voltage suppression by RC,
(Charges the leakage voltage to PSDZ1 and PSCX1
and discharges to PSRZ1, PSRZ2).
3) PPCF2 : For noise removal
(c) PQIZ1 Vcc circuit
1) PVRL1, PVRL2, PVRL3 : PQIZ1 driving resistance (PQIZ1 works through driving resistance at power cord in)
2) PQIZ1 Vcc : PVRL4, PVDL1, PVCL1
!
Use the output of transformer as Vcc,because the current starts to flow into transformer while PQIZ1 is
active
@
Rectify to PVDL1 and smooth to PVCL1.
#
Use the output of transformer as PQIZ1 Vcc : The loads are different before and after PQIZ1 driving.
(Vcc of PQIZ1 decreases below OFF voltage , using only the resistance dut to lode increase after PQIZ1
driving.)
(d) Feedback Control Circuit
PPDD2
3.3V
3
Fig. 13-3