Nokia 447ZiPlus Service Manual page 31

17” colour monitor
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(3) No Raster appear
No
Check B+ converter
CKTQ440, Q438,
Q439, D442
No
Replace the
defective
No raster appear
Is
the H.V.
correct
?
No
Is the
voltage at O/P
of D442 normal
(69...165V)?
Yes
Is the
waveform at
Pin 1 of T430
normal ?
Yes
Open L440, Input 31KHz
signal apply 80V DC on
Pin 9 of T440
Is the
voltage at
cathode of
D453 normal ?
Yes
Are
No
Q433,
D434 OK ?
Yes
Check T440, P440,
T430, CRT
Yes
Does raster
light up with
SCREEN control
turned clockwise
?
No
Is the
voltage at
heater normal
(6.3V) ?
No
Check R930, P902
No
Is the
waveforms at
Pin 26 of I401
normal ?
No
Check I401
No
Is the
high voltage
protection CKT
active ?
29
Yes
Reset SCREEN
control.
Yes
Check brightness
circuit Q495,
Q497, R482
Check spot killer
Ckt Q348, D348
Check FBT, CRT
Yes
Check Q429,
D428, C427, R424
+14V to Q429
–9V to Q429
Yes
Check D446, D449
R447, R445, C434,
C435, C451, P440,
L483

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