Sharp VC-M23SM Servicehandbuch Seite 34

instrument af
[input signal EtA colour bar(1.0ve-p) |
[Testpoint [VIDEO OUT jack
0.95 + 0.1Vp-p -
Connect a 75 ohm terminating resistor to the VIDEO
OUT jack and connect an oscilloscope across this
- terminating resistor.
(See Note below.)
2. Feed a colour bar signal to the VIDEO IN jack.
3. Make sure that the E-E signal amplitude is 1.0Vp-p as
shown in Figure 5-3.
Specification
al
Notes: Figure 5-3. | es
If the 75 ohm terminating resistor is missing, the signal
amplitude wiil be doubled.
CHECKING OF WHITE CLIP LEVEL
Oscilloscope
E-E or Record
EIA colour bar (1.0Vp-p)
|
Pin(48) of IC401, GND
190 + 5% (See note below)
1, Connect an oscilloscope to pin (48) of IC401 and
GND.
2. Feed the colour bar signal to the VIDEO IN jack and
set the unit in E-E or recording mode. .
3. Make sure that the overshoot of the video signal is
clipped at 190% as shown in Figure 5-4.
SYNCTIP
Measuring
instrument
Mode
Input signal
Test point
Specification
100%
190%
100% WHITE
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WHITE CLIP LEVEL
Figure 5-4,
34
'Note:
From sync tip to whité peak, the level is 100%.
'The white clip level is 90% above the white level.
'CHECKING OF RECORD LEVEL
| Measuring Dual-trace oscilloscope
| instrument ;
[ u o t e | Resortmede
: input signal EIA colour bar (1.0Vp-p) -
| Test point Chroma (Red) —— |
R514 terminal lead at L509 side
(Sig.)} ~ GND
Sync tip
R225 terminal lead at L210 side
(Sig.) ~ GND
| Specification
Chroma (Red): 205~290mVp-p
Sync tip: 150~220mVp-p
1. Feed the colour bar signal to the VIDEO IN jack and
set the unit in recording mode.
2. Connect a dual -trace oscilloscope to each test point
shown in table.
3.. Make sure so that the amplitude of the chroma (Red)
portion andthe sync tip portion are specified as shown
in Figure 5-5.
Red
ioe oC
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SHAT © Syne. tip VOM -
Level TTT
Figure 5-5 (b).
Figure 5-5 (a).