Vibrato - Hammond L series Service Manual

3.0V and 5.5V
rms.
With
PERClMBN
SOFT
tablet depressed,
output should
be 1.5V
to
2.8V
rms.
i.
Vibrato check. Depress
FULL
ORGAN
tab.
Hold
down
F, A,
C
chord near center
of
upper manual. Depress
VIBRATO
SMALL
tab
and
observe vibrato
effect.
Then,
in addition, depress
VIBRATO
NORMAL
tab.
Vibrato
effect
should
increase. In addition, press
VIBRATO
CHORUS
tab.
Vibrato
effect
should
be-
come more
pronounced.
NOTE
Later organs, Figures
5—2
through
5—4,
are
equipped
v^ith
vibrato
width potentiometer R131. Ad-
just
if
vibrato effect
is
too
narrow
or
too
broad.
j.
Reverberation check. Depress
FULL
OR-
GAN
tab.
Hold
down
F, A,
C
chord near
center
of upper manual.
Add
REVERB
I
tab.
Observe that reverberation
is
heard
as
chord
is
played and
released.
Add
REVERB
II
tab.
Reverberation should
be increased
relative to
REVERB
1
tab
as
chord
is
played
and
released.
k.
Microphonics
and
Hum
check.
1
.
Tap
each tube and
replace
it
if
there
is
ring
or
howl
in
the speaker with
expression pedal
maximum
and
VOLUME
SOFT
tab
not
depressed.
2.
Hum
in speakers
with expression pedal
maximum
and
VOLUME
SOFT
tablet
not
depressed
must
be very
low
in vol-
ume
and not measure
more
than
15
mV
rms.
If
hum
is
excessive, see para-
graph
4-22.
NOTE
On L- 100-2
the
SILENT-SOUND
tab
on
Rhythm
II
must
be
in
SI-
LENT
position.
VIBRATO. -
To
check
vibrato
proceed
ac-
cording to the following.
a.
Pull
out
upper manual 2'
drawbar
to
position
8.
All
other drawbars
in.
De-
press
UPPER
DRAWBARS
tab.
b.
Remove
the
phono
cable
from
the
BN.
phono
jack located
on
the
preampUfier
chassis.
Connect
the
scope
VERTICAL
INPUT
to the
phono
plug removed.
c.
Remove
the
phono
cable
from
the
BK.
phono
jack located
on
the vibrato
phase
shift
ampUfier. Insert into the
BK. phono
jack
an adapter with
two phono
jacks
and one
phono
plug.
Reconnect
the
phono
cable (black) into
one of
the
adapter
phono
jacks
and connect
the
scope
EXT.
TRIGGER
IN
binding post
to the remaining adapter
phono
jack.
d.
Set
scope
controls
as
follows:
1.
TRIGGER:
SOURCE
-
EXT.,
COUPLING -
AC;
SLOPE +
2.
HORIZONTAL
SWEEP -
0.2
msec/cm.
3.
VERTICAL
SENSITIVITY
-
0-2
volt/cm.
e.
Hold
down
key #7
(frequency #60)
on
the
upper manual.
f.
Adjust
the
TRIGGER LEVEL
control
for
a stable
pattern.
g.
Adjust
the
VARIABLE
sweep time
control
until
one complete sinewave
covers
4 cm.
h.
Adjust the
VERTICAL VARIABLE
con-
trol
for a display height
of 4
cm.
i.
Depress the
VIBRATO
NORMAL
tab.
Adjust
the
VIBRATO WIDTH
control
for a
total
phase
shift
swing of 2 cm.
(refer
to Figure
4-1).
If
VIBRATO
WIDTH
control does not
give satisfactory
result, select
R133,
Figure
5—1
through
5-4
between
220a
and
IK.
2
CM
/2CM
Figure
4-1.
Vibrato
Adjustment
Waveform
NOTE
Phase
shift
can be read
best
if
waveform
is
centered
so that
the
center
peak of the sinewave
coin-
cides
with
a graticule
line.
j.
Release
VIBRATO
NORMAL
tab. Single
wave must
be centered
±
Vi
cm.
as
shown
in
Figure
4—1.
k.
Disconnect
external leads
and
adapter.
Reconnect phono
cables to
proper
jacks.