7-1. Dynamic Focus
| FVH | FVV | Focus is poor | |
PHILIPS | : 440V | 180V | ||
| ||||
NEC | : 300V | 120V |
| |
SAMSUNG : 300V | 120V |
| ||
|
| DF |
| |
|
| waveform | Is the | |
|
|
| ||
FVH |
|
| waveform of the | |
| FVV | DF pin in FBT | ||
|
| correct? | ||
No
Is the
cathode voltage
of the D575 about 600V?
Yes
*Check after adjusting the static focus finely by VR in FBT
Yes |
| 1. Check the CRT socket |
| or connector wire | |
|
| |
| ||
|
| 2. Trouble in FBT or CRT |
|
|
|
No |
| 1. Check the waveform of |
|
| the pin 3 of FBT. |
| ||
|
| 2. Check D575 |
|
|
|
4.5V
2V
0V
| Is the | No | |
| base voltage of | ||
| the Q751 about |
| |
| 2.6V? |
| |
|
| Yes |
|
|
|
| |
|
|
|
|
| Is the | No | |
| waveform of | ||
DF | the pin 10 in IC501 |
| |
| |||
correct? |
| ||
waveform |
| ||
|
|
| |
Yes
0.8V
Trouble in Q752, Q753, Q754,
D751, D752, D753, D754,
Q755, Q756
1.Check the 12V DC line.
2.Check Q751,D755
Trouble in IC501 or C520
23
