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3.
Slowly
advance
R202
clockwise
(CW) to a point slightly
beyond the point of minimum
snow.
Note:
Do not advance
the control any further as it may result in
an overload
caused by a strong signal,
The range of the AGC
voltage
supplied
to Pin 5 of the U/V Tuner will vary from 8Vdc
(Without
Signal) to just less than a lVdc.
VCO & AFT Adjustment
1.
Cut the shield
break-points
around
IC200
and
the IF
Circuitry.
Peel back
the top cover
of the shield
to gain
access to the internal circuitry.
2.
Short Test Points 16A & 16B together
at the bottom of the
U/V Tuner.
3.
Short
Test Point 23 (Pin 13 of IC200)
to ground
(Shield
around IC200 is good).
4.
Connect a DC Voltmeter to Test Point 7 (Pin 18 of IC200).
5.
Turn the set On and record the voltage
reading
from Test
Point 7 (typically 4.5 to 5.0Vdc).
6.
urn Off the set and remove
both shorts
from Test Points
TP16A/B
and TP23.
7
.Adjust the VCO Coil (L204) to obtain the same dc voltage
reading at Test Point 7 that was recorded
in step 5.
8.
Connect
the Coincidence
line at the collector
of Q203
(jumper
B37, near the J-TEST
Connector)
to 5Vdc (Pin 3 of
IC401 or the Anode of D401).
9.
Apply a local broadcast
signal (air signal) to the antenna ter-
minals and turn the set On.
10
Select the Cable Tuning from the menu system.
Select any
high band inactive cable channel (Channel 36).
11.
While still in the cable mode, now select a local VHF broad-
cast channel.
The Tuning System will attempt to tune three
times
and then lock onto the FCC assigned
frequency
for
that channel.
12.
Adjust the AFT Coil (L202) to obtain a reading of 7.1Vdc (+/-
25mVdc)
at TP2.
13.
Remove the jumper from the Coincidence
line.
14
Verify this adjustment
by changing
between
the high band
(inactive cable channel)
and your local VHF broadcast
chan-
nel (ensure that the local broadcast
channels
lock in quickly).
13
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