Adjustment Procedures - Sharp 4M-IOM Service Manual

ADJUSTMENT PROCEDURES

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Adjusting Conditions
. + B ADJUSTMENT : VR701
1. Connect the DC voltage meter to TP701.
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1. Feed sweep signal to TP20 I.
2. Add fixed bias to TP202 (Pin (1) of IC201)
3. Connect an oscilloscope to TP203.
l AFT ADJUSTMENT : L210
1. Feed IF sweep signal to TPl 01.
2. Add fixed bias to TP202.
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3. Connect the oscilloscope to TP204.
. RF-AGC ADJUSTMENT : VR201
1. Feed colour bar signal.
(Set the input field strength to 58 dBp)
2. Check the below
Sound mode : AUTO
. AFT FINE ADJUSTMENT : L210
1. Apply the output from the SG (Signal Generator)
to the TPlOl.
(Output from SG : 38.9MHz (CW) 100dBp)
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Adjusting Procedures
1. Adjust VR701 so that the + 5V line becomes
5 f 0.05v.
1. Adjust 1209 to make the 38.9MHz marker as low
as possible.
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1. Adjust L210 so that the 38.9MHr marker be
positioned as shown below.
1. Adjust VR201 so that the voltage at TPlO2 be
3 ?O.lV.
1. With the tuning in UP search mode, adjust L210 so
that the voltage at TP204 be 2.25V.
ADJUSTMENT PROCEDURES
Adjusting Conditions
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1. Feed colour bar signal.
(Set the input field strength to 58dBp)
2. Connect a the DC voltage meter to TP205.
l SIGN POSlTlON ADJUSTMENT : VR401
1. Feed colour bar signal.
(Set the input field strength to 58dBp)
(0)
2. Set the MODE switch 5401 to MEMORY
position.
l SIGN ADJUSTMENT : VR501
1. Set the MODE switch 5401 to SEARCH (HI)
position.
2. Connect a diode and lk ohm resistor between
pins (16) and (33) of IC401. Set the unit to
MANUAL SEARCH mode.
3. Connect pin (24) of lC501 to the + 5V line and cut
off the AFT.
(Continued )
Adjusting Procedures
1. Adjust L301 so that the voltage at TP205 be
1. Using the CH-CALL button, make "20-20" on
screen.
2. Adjust VR401 to position the "20-20" sign as
2 0 - 2 0 '
1. Using the UP/DOWN key (A , v), set the channel
bar at the leftmost end of the VHF sign (just
before changing to the UHF sign).
See the figure below.
2. Adjust VR501 so that the tuner's BT voltage at pin
(4) be 0.2V f O.lV.