Sony ICF-6800W - Page 44

14. VCO2 ADJUSTMENT
Note: This adjustment may not be made if the variable
capacitor CV1-8-11 of VCO2 is installed improperly
when it is replaced. Refer to the capacitor installa- .
tion on page 34.
Procedure:
1. Disable the sweep circuit as shown below.
Ground lead of R225.
Remove insulation
Coating.
main board
(component side)
. BAND SELECTOR switch: MW
. Turn the MW/SW TUNING DIAL to obtain a
600 kHz indication on the internal counter.
. MODE switch: WIDE
BAND SELECTOR switch: SW
. SW BAND SELECTOR: any frequency between
10,000 and 19,000 kHz.
—~47—
| ICF-G8OOW ICF-6800W |
VOM
(range: 10 V de)
test point
main board
Note: Continue the steps when the circuit of VCO 2 is chang-
ed or the phase detector (Q53, Q55—Q57) is replaced.
In other cases, skip the steps 7 through 10.
7. Set the SW BAND SELECTOR switches as shown
below to obtain a 15,500 kHz indication on the
counter.
SW BAND SELECTOR
+
between the
clicks of “5” and “6”
(continued on next page)
. Adjust VT1 so that VOM connected in step 6
indicates approximately 3.5 V. Keep the frequency
indication on the frequency in 15,500 kHz by fine
adjusting SW BAND SELECTOR, because the
frequency changes when VT1 is adjusted.
. SW BAND SELECTOR switches: 10 MHz
. Adjust L36 so that the frequency counter indi-
cates just 10,000 kHz.
. SW BAND SELECTOR switches: 19 MHz
. Adjust CT11 so that the frequency counter indi-
cates just 19,000 kHz.
. Perform step 7. Read the indication of the VOM
as connected in step 6. ( @) Vv)
. SW BAND SELECTOR: 15 MHz
. Slowly turn the 1 MHz-step SW BAND SELECTOR
switch from “5” to “6” observing the VOM indica-
tion. The VOM indication gradually lowers and
suddenly goes back up to the first reading.
Read the VOM indication just before the reading
goes back ( V ). This should happen between
15,000 and 16,000 kHz.
. Set the 1 MHz-step SW BAND SELECTOR switch
to “5” (15,000 kHz).
. Gradually turn the 1MHz- step SW BAND SE-
LECTOR switch from ‘5’ to ‘‘4” observing the
VOM indication. The VOM indication gradually
rises and suddenly goes down to the first reading
at a point. Read the VOM indication just before
the reading drops. ( © V), This should happen
between 14,000 and 15,000 kHz.
. V.®@v and V become as follows.
(A) V-@)V=©v-@v
should be equal
If not, perform steps 7, 8 and 13 through 18.
. Set the 1MHz-step SW BAND SELECTOR switch
to “Q”,
. Adjust L36 so that the VOM reading becomes @ Vv
and
the
counter
indicates
10,000
kHz.
.
Set the
1
MHz-step
SW
BAND
SELECTOR
switch
to sg? 7
22. Adjust CT11 so that the VOM reading becomes
@) V and the counter indicates 19,000 kHz.
23. Turn the 1 MHz-step SW BAND SELECTOR
switch from ‘0’? to “9” successively. The
frequency counter should indicate 10,000kHz,
11,000, kHz 19,000kHz respectively. If
not, repeat steps 1 through 22.
24. Remove the grounding wire installed in step 1.
Adjustment Location:
— main board —
— 48 —