Samsung SCA20 Service Manual page 55

5-3 VCR Section Adjustment
5-3-1 Preparations
1. Equipment :
1) Monitor TV.
2) Dual trace oscilloscope of over 20MHz band,
incorporates delay mode.
(Use 10 : 1 probe unless otherwise specified.)
3) Frequency counter
4) Pattern generator with video output terminal.
5) Digital voltmeter.
6) DC power supply.
7) Alignment tape (Color bar : SP)
2. Composition of VCR PCBoards
1) Main PCB (system control/servo, video,
audio,DC/DC converter, camera)
2) Rear PCB
3) Battery-Terminal PCB
4) Front PCB
3. Set-up during adjustment
Since the video output signal obtained from the
pattern generator is used as the adjusting signal for
the VCR block, it is necessary that this video
output signal be within the required specifications.
Connect an oscilloscope to video input jack and
make sure that the amplitude of the video SYNC
signal is approximately 0.3V, that the video block
amplitude is approximately 0.7V, that the burst
signal amplitudeis approximately 0.3V with fiat
characterics, and the signal level ratio between the
burst signal and ÒRedÓ signal is 0.30 : 0.66.
The video signal ( color bars ) used for VCR block
electrical adjustment are shown in figure 1.
Samsung Electronics
APPROX.
0.7V
APPROX.
0.3V
Fig. 1 Color bar signal pattern generator
4. How to get into srvice ÒADJUSTÓ mode
STEP 1
1. Connect the power source (battery/DC cable).
2. Set the knob-power of the camcorder to VCR
position.
3. Press the ÒEJECTÓ button to eject mode.
STEP 2
1. Press and hold ÓEJECTÓ button and ÒDATEÓ
button on the REAR board at the same time for
more than 5 seconds.
2. If OSD Shows like the figure below, VCR
adjustment mode has been successfully
activated.
3. Insert tape into housing assy and then
perform the adjustments.
0. EMPHA
EPR:XX EVR:XX
Alignment and adjustment
WHITE(APPROX. 100%)
1.0 0.05Vp-p
H
0:00:00
5-25