Sharp 55R-WP4H, Service Manual

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26
61R-WP5H
55R-WP5H
No. AdjustingPoint Adjusting Conditions Adjusting Procedure
1 VCO adjustment
(L205 and L108 on
Tuner Unit) Signal: Good local channel
Adjusting point:
L205 and L108
Specification:
2.2 ±0.1 Vp-p
1. Receive the good local channel.
2. Connect the digital voltmeter to pins (15) and (17)
of TB connector to ground.
3. Select the Service mode.
4. Adjust the VCO coils (L205 and L108) to have the
2.2V level. (Main: L205, Sub: L108)
5. Quit the Service mode.
2 RF AGC adjust-
ment (R215 and
R115 on Tuner
Unit) Signal: Good local channel
Adjusting point:
R215 and R115
Specification:
No noticeable noise
1. Receive the good local channel.
2. Adjust R215 and R115 to achieve optimum screen
without noises and beats. (Main: R215, Sub: R115)
3. Receive other channel signals. Check the screen
as mentioned in the above step 3.
Note :
When the R215 and R115 controls are set to mini-
mum, there will be nothing seen on the screen
(black raster).
3 Detector output
level adjustment
(R238 and R136 on
Tuner Unit) Signal: NTSC standard half
color bar signal
Adjusting point:
R238 and R136
Specification:
1.0 ±0.05 Vp-p
1. Receive the NTSC standard half color bar signal.
2. Connect the oscilloscope between TP201 (TP101)
on Tuner Unit and GND. (Main: TP201, Sub: TP101)
3. Using the R238 control, adjust the main IF detec-
tion output level.
4. Using the R136 control, adjust the sub IF detec-
tion output level.
1.0Vp-p