LG PF-43A10 Service Manual page 28

3. Horizontal/Vertical Deflection
3-1 Horizontal Drive circuit
1) Summary
Horizontal drive circuit connected between horizontal
deflection output and horizontal oscillation circuit supplies base
current to operate horizontal output transistor and does as
2) Circuit Diagram
3) Description
Horizontal drive waveform a signal from Pin6 of TA8880AN
is fed to base of Q421 through R421.
Waveform B is determined by R421.
+
B (45V) is fed to the collecttor of Q421 through R427 and the
waveform of Q421 collector is waveform C.
The role of R423 and C421 is to correct the waveform
appearing the collector of Q421.
4) Waveform
Q421
TA8880AN
R421
6
buffer amplifier to maintain the frequency of horizontal
oscillation circuit from the effect of horizontal output circuit.
Q422
T421
1st
2nd
R423
C421
C406
R417
+
B =45V
The voltage waveform of Q422 base is waveform D and its
current waveform is waveform E. In condition of waveform
E, Ib 1 determines the saturation condition of Q421 and Ib2
reduces the switching loss when Q422 is switched off.
Also, the ratio Ib1/Ib2 is related to that of T421 Turns (N1 :
N2).
(A) TA8880AN, Pin6
voltage waveform
(B) Q421, Base
voltage waveform
(C) Q421, collector
voltage waveform
(D) Q422, Base
voltage waveform
Ib1
(E) Q422, Base
Current
Ib2
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