JVC AV-20D304/SA Service Manual page 18

3.6 ADJUSTMENTS PROCEDURE
3.6.1 CHECK ITEM
Measuring
Item
instrument
B1 POWER DC voltmeter
SUPPLY
Signal
generator
3.6.2 VCO
Measuring
Item
instrument
IF VCO Remote
control unit
TOO HIGH
3.6.3 RF AGC
Measuring
Item
instrument
RF AGC Signal
generator
Remote
control unit
No Setting item
S21 AGC ADJ
Test point Adjustment part
B1 Connector
TP-91
TP-E
[MAIN PWB]
Test point Adjustment part
[9.VCO]
CW transf. (T111)
[MAIN PWB]
GOOD TOO LOW
SYNC: YES
AFC ON
FINE 0
Test point Adjustment part
[1.V/C(S)]
S21 : AGC ADJ
Variable Initial setting
range value
0~127 80
Description
(1) Receive the black and white signal. (color off)
(2) Connect the DC voltmeter to TP-91 (B1 connector 1
pin) and TP-E (B1 connector 3 pin).
(3) Confirm that the voltage is DC134V±2V.
Description
• It must not adjust without inputting the RF signal.
(1) Receive a broadcast.
(2) Select 9.VCO in the SERVICE MENU.
(3) Confirm that the color change from "TOO HIGH" to
"TOO LOW" by CW transf. on MAIN PWB, and
check the "SYNC : YES".
(4) Adjust CW transf. until "GOOD" letters turns green.
And then confirm that the "SYNC : YES" again.
Adjustment can be done in this statement.
(5) Push the [EXIT] key to exit the [9.VCO] mode.
Description
(1) Receive a black and white signal (colour off).
(2) Select <S21>(AGC ADJ) of the 1.V/C(S).
(3) Press the [MUTING] key and turn the picture color
off.
(4) With the [VOLUME (-)] key to get the noise in the
screen picture (zero side of setting value).
(5) Press the [VOLUME (+)] key several times and step
when noise disappears from the screen (at that time,
not to increase the value too much).
(6) Change to other channels and make sure that there
is no irregularity.
(7) Press the [MUTING] key and get color out.
AV-20D304
(No.52103)1-17