Daewoo 710B Wartungshandbuch PDF herunterladen (Seite 25)

23

7-1. Dynamic Focus

Focus is poor

Is the

waveform of the

DF pin in FBT

correct?

PHILIPS : 440V 180V

NEC : 300V 120V

SAMSUNG : 300V 120V

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

* Check after adjusting the static focus

finely by VR in FBT

DF

waveform

FVH

FVH FVV

FVV

No

Is the

base voltage of

the Q751 about

2.6V?

Yes

Yes

Yes

Is the

waveform of

the pin 10 in IC501

correct?

Yes

No

No

Trouble in Q752, Q753, Q754,

D751, D752, D753, D754,

Q755, Q756

Trouble in IC501 or C520

No

DF

waveform

4.5V

2V

0V

0.8V

Is the

cathode voltage

of the D575

about 600V?

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