Adjustment - JVC KB-700 Service Manual

B-700 B/N/H
Adjustment
Adjustments should be performed in the order of the numbers.
Item
IVleasuring
device
Adjusting
point
Measuring
point
Conditions
Main
oscillator
frequency
(Organ)
Frequency
counter
CP Board
LI coil
R17
Orchestra preset: Organ
Orchestra volume: MAX.
Main pitch: Center
Solo
oscillator
frequency
(Solo,
Synthe.)
By ear DM Board
LI coil
Solo preset: Pan flute
Solo volume: Center
Orchestra preset: Organ
Orchestra volume: Center
Solo pitch: Center
Accomp.
strings
envelope
Oscillo¬
scope
CP Board
R229
R45
Key split: 1
Accomp. string: MAX.
Adjusting Method
Depressing A6 key (highest La) turn the
coil LI so that the frequency becomes
7072 Hz.
Depressing a key as your option and hear¬
ing sound, adjust LI so that the sound be¬
comes zero beat.
Turning ON and OFF C3 key repeatedly
adjust R229 to obtain the following value.
A : B = 2 : 1
Key ON
Key OFF
Accomp.
strings
signal
Oscillo¬
scope
CP Board
R228
Key split: 1
Accomp. string: MAX.
Turning ON A2 key adjust R228 so that
C is equal to D.
Tremolo
speed
Frequency
counter
RS Board
R521
Junction
of R446
& R447
Brass
VCF
cutoff
Oscillo¬
scope or
AC valve
voltmeter
RS Board
R520
AUX OUT
L-ch
Solo VCF
cutoff
frequency
Oscillo¬
scope or
AC valve
voltmeter
RS Board
R321
AUX OUT
L-ch
SoloVCA
cutoff
level
Oscillo¬
scope
RS Board
R320
AUX OUT
L-ch
Tremolo SW: ON
Orchestra volume: MAX.
Solo volume: MAX.
Solo volume: MAX.
Adjust R521 for 6.6 Hz.
Turn R520 counterclockwise to open VCF
and turn C4 key ON, too, to measure the
value of level.
Then turning C6 key ON in the same con¬
dition, adjust R520 to obtain the same
value as the former.
Turn R320 fully counterclockwise (con¬
tinuous sound can be heard even in key
OFF condition, then turn R321 counter¬
clockwise (VCF open).
Turn E2 key ON and measure value of the
level. Then, holding C6 key turned ON,
adjust R321 to obtain the same value as
the former.
Turning on A6 key repeatedly, adjust
R320 to obtain the following value,
i E : F = 2 : 1
10