Sony BKM-V12, Руководство по обслуживанию

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2-13
PFM-42X1/42X1N
3. SCAN IC (Y drv B/D : IC1 to 12) damage
1) If the SCAN IC has a failure, one horizontal line may
not be display on the screen.
. Test point : ICT measurement of GND through Y
drive B/D output.
.
Waveform : As shown in Fig. 5.
Fig. 5 When SCAN IC is poor
2) The screen may not be displayed when the SCAN IC is
damaged due to the SCAN IC failure, external electric-
ity or spark.
.
Test point : ICT measurement of GND through Y
drive B/D output.
. Waveform : Output waveform is not output (The
damage can be seen in the SCAN IC on
the top or bottom of the Y drive B/D).
3) The screen may fluctuate horizontally when the cable
on the top or bottom of the Y B/D is damaged.
.
Test point : ICT measurement of GND through Y
drive B/D output.
. Waveform : As shown in Fig. 6.
Fig. 6 When the Y drv B/D top or bottom cable is damaged
SCAN pulse does not occur
When the internal output FET
of IC is damaged
Normal scan pulse
Noise occurance at scan section
4) If the SCAN IC output is shorted by a dust or a foreign
substance, two horizontal lines may overlap on screen.
.
Test point : ICT measurement of GND through Y
drive B/D.
. Output waveform : As shown in Fig. 7.
Enlarge the scan pulse
Decrease voltage of the
scan pulse
Widen the pulse width
SCAN section
SCAN PULSE
<SCAN IC normal output wave>
.
Measuring position : The enlarged SCAN section after
measuring the output ICT of the Y
drive B/D. (Full White pattern).
Fig. 7 When SCAN ID output is shorted