Dynamic Focus - Daewoo 712B Service Manual

7-1. Dynamic Focus

F
VH
ORION : 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
No
Is the
cathode voltage
of the D605
about 700V?
Yes
Is the
base voltage of
the Q303 about
2.6V?
Yes
Is the
waveform of
the pin 10 in IC501
DF
correct?
waveform
Yes
0.8V
Trouble in Q303, Q304,
Q302,Q301
* Check after adjusting the static focus
finely by VR in FBT
Yes
No
No
No
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 D605
1. Check the 12V DC line.
2. Check Q303, Q302
Trouble in IC501 or C508