D2
Q2
CT
D1
CS
B+
Q1
Cm
Csm
Lm
DY
Vm
+28V
H-Width
Q3
U1
+
-
Va
Vb1
I1
70
5.
Horizontal amplitude control
Circuit Diagram
Description of the circuit:
1) The diodes D1 and D2 compose the bipolar modulation circuit, and have the function of controlling
the currents of the oils DY(lpp) and Lm(lm) through voltage modulation carried out by utilizing VM.
B+ = Vm +Vcs
Therefore, Vcs = (ly * Ly)/ts
→
ly = (Vcs * ts)/Ly, with B+ fixed.
Such being the case, the horizontal width decreases when Vm
↑
→
Vc
↓
→
ly
↓
Inversely, the horizontal width decreases when Vm
↓
→
Vcs
↑
→
ly
↑
(B+ = (Vp*2Tr)/(
π
*Ts), Tr =
¡Ô
¡Ô
¡Ô
¡Ô
¡Ô
LyCt, Tm =
¡Ô
¡Ô
¡Ô
¡Ô
¡Ô
LmCm)
2) Q2, Q3 and U1 compose the control circuit of H-WIDTH. Of those devices, the transistor Q2 and Q3
compose the Darlington current amplifier, and on the other operational amplifier U1 compose the
emitter-coupled circuit, that stabilize the voltage and control the current.
3) The horizontal width broadens when Va
↑
→
VbI
↓
→
I1
↑
→
I2
↑
→
Vm
↓
→
. An inference in
the opposite sense is also possible.
Test points for maintenance:
1) C
T
= 31 to 37 kHz = 3.2 us
48 to 64 kHz = 3.0 us
Cm
÷
2.8 us
2) V
A
CENTER: 31 to 64 kHz
¡Ü
¡Ü
¡Ü
¡Ü
¡Ü
1.91 to 4.06V
V
M
CENTER: 31 to 64 kHz
¡Ü
¡Ü
¡Ü
¡Ü
¡Ü
11.6 to 27.4V
Summary of Contents for MultiSync 75F-3
Page 56: ...DDC Flow Chart 53 ...
Page 57: ...Master I C Flow Chart 54 ...
Page 58: ...Master I C restart mode Flow Chart 55 ...
Page 59: ...Slave I C Flow Chart 56 ...
Page 61: ...BLOCK DIAGRAM I C bus autosync deflection controller for PC monitors TDA4857 58 ...
Page 71: ...I C bus autosync deflection controller for PC monitors TDA4857 68 APPLICATION INFORMATION ...
Page 77: ...74 8 Monolithic triple 13 5nS CRT driver ...
Page 78: ...75 ...
Page 79: ...76 ...
Page 80: ...77 ...
Page 102: ......
Page 103: ......
Page 104: ......