Sharp 34N-WF5H, Service Manual

Page: 15 / 87

15
34N-WF5H
No. AdjustingPoint Adjusting Conditions Adjusting Procedure
1 VCO adjustment
(L205 and L255 on
Tuner Unit) Signal: Good local channel
Adjusting point:
L205 and L255
Specification:
2.2 ±0.1 Vp-p
1. Receive the good local channel.
2. Connect the digital voltmeter to pins (28) and (29)
of JA connector (SC1401).
3. Select the JWS address 033 and set it to "1".
4. Adjust the VCO coils (L205 and L255) to have the
2.2V level. (Main: L205, Sub: L255)
5. Set the JWS address 033 to "0".
6. Clear the JWS address 033 and quit the JWS
mode.
2 RF AGC adjust-
ment (R219 and
R269 on Tuner
Unit) Signal: Good local channel
Adjusting point:
R219 and R269
Specification:
No noticeable noise
1. Receive the good local channel.
2. Select the JWS address 033 and set it to “1”.
3. Adjust R219 and R269 to achieve optimum screen
without noises and beats. (Main: R219, Sub: R269)
4. Receive other channel signals. Check the screen
as mentioned in the above step 3.
5. Set the JWS address 033 to “0”.
6. Clear the JWS address 033 and quit the JWS
mode.
Note 1:
Before switching to other channels (in Step 4 .
above), take Steps 5. and 6. and quit the JWS
mode.
Note 2:
When the R219 and R269 controls are set to mini-
mum, there will be nothing seen on the screen
(black raster).
3 Detection output
level adjustment
(R233 and R283 on
Tuner Unit) Signal: NTSC standard half
color bar signal
Adjusting point:
R233 and R283
Specification:
1.0 ±0.05 Vp-p
1. Receive the NTSC standard half color bar signal.
2. Connect the oscilloscope between TP401 (TP402)
on Tuner Unit and GND. (Main: TP401, Sub: TP402)
3. Using the R233 control, adjust the main IF detec-
tion output level.
4. Using the R283 control, adjust the sub IF detec-
tion output level.
1.0Vp-p