Dynamic Focus - Daewoo 710B Service Manual

7-1. Dynamic Focus

F
VH
PHILIPS : 440V 180V
NEC : 300V 120V
SAMSUNG : 300V 120V
F
VH
4.5V
2V
0V
F
VV
Focus is poor
DF
waveform
Is the
waveform of the
DF pin in FBT
F
correct?
VV
Is the
cathode voltage
of the D575
about 600V?
Is the
base voltage of
the Q751 about
2.6V?
Is the
waveform of
the pin 10 in IC501
DF
correct?
waveform
0.8V
Trouble in Q752, Q753, Q754,
D751, D752, D753, D754,
Q755, Q756
* Check after adjusting the static focus
finely by VR in FBT
Yes
No
No
Yes
No
Yes
No
Yes
23
1. Check the CRT socket
or connector wire
2. Trouble in FBT or CRT
1. Check the waveform of
the pin 3 of FBT.
2. Check D575
1. Check the 12V DC line.
2. Check Q751,D755
Trouble in IC501 or C520