Alignment Instructions - Zenith 19M20 Manual

ALIGNMENT INSTRUCTIONS
1.
2.
3.
4.
The high voltage lead should be securely taped and kept away from the chassis. Do not remove the horizontal oscillator tube (V14) to disable the
high voltage .
VIDEO IF ALIGNMENT
Connect the negative lead of a 2 volt bias supply to the ungrounded side of C31.
Connect the positive side to chassis.
Connect the synchronized sweep voltage from the sweep generator to the horizontal input of the oscilloscope for horizontal deflection.
DUMMY
ANTENNA
470MMF
SWEEP
GENERATOR
COUPLING
High side to pin 1 (grid)
of 6CB6 (V5). Low side
to chassis.
High side to point <^> .
Low side to chassis .
SWEEP
GENERATOR
FREQUENCY
43MC
(10MC Swp)
MARKER
GENERATOR
FREQUENCY
39.75MC
45.75MC
39.75MC
41.25MC
47.25MC
42.75MC
«.OMC
45.75MC
CHANNEL
Any non
interfer-
ing
channel
CONNECT
SCOPE
Vert. Amp. thru
10KSJ to point <$> .
Low side to chassis
ADJUST
A1.A2
A3.A4,
A5
A6, A7,
A8,A9
REMARKS
Attenuate generator output for 3 volts
peak to peak on scope. Adjust for response
curve of maximum amplitude and sym-
metry similar to Fig. 1.
Remove bias battery. Use maximum
scope gain to amplify trap region of
response curve as in Fig. 2. Adjust for
MINIMUM marker amplitude. Reconnect
bias supply.
Attenuate sweep generator output to
maintain not more than 3 volts peak to
peak on scope. Alternately adjust A6 thru
A9 to obtain response similar to Fig. 3.
A6 affects the high side and A7 affects
the low side of the response curve.
OSCILLATOR ALIGNMENT
The master oscillator adjustment, A10, is to be made only if the individual channel oscillator adjustment fails to bring the channel within the
range of the fine tuning control. If channels 2 thru 6 fall within the range of the fine tuning control
but the higher channels do not , slight adjustment of A10 may be necessary to bring in the higher channels ,
Connect the negative lead of the bias supply to the ungrounded side of C31. Connect the positive lead to chassis. Adjust for -1 volt at C31.
Turn up the scope gain so that the sound trap notch in the response curve becomes visible,.
Connect the synchronized sweep voltage from the sweep generator to the horizontal input of the oscilloscope for horizontal deflection.
The sweep generator output lead should be terminated with its characteristic impedance, usually 50 ohms.
Set the fine tuning control to the mid-position of its range.
DUMMY
ANTENNA
Two 120S2
Carbon
Resistors
SWEEP
GENERATOR
COUPLING
Across antenna ter-
minals with 120S2 in
each lead.
SWEEP
GENERATOR
FREQUENCY
57MC
(10MC Swp
63 MC
(10MC Swp
69MC
(10MC Swp
79MC
(10MC Swp
85MC
(10MC Swp
177MC
(10MC Swp
183MC
(10MC Swp
189MC
(10MC Swp
195MC
(10MC Swp
201MC
(10MC Swp
207MC
(10MC Swg
213MC
(10MC Swp
MARKER
GENERATOR
FREQUENCY
59.75MC
65.75MC
71.75MC
81.75MC
87.75MC
179.75MC
185. 7 SMC
191.75MC
197.75MC
203.75MC
209.75MC
215.75MC
CHANNEL
2
3
4
5
6
7
8
9
10
11
12
13
CONNECT
SCOPE
Vert. Amp. thru
lOK.fl to point <£> .
Low side to chassis
ADJUST
All
A12
A13
A14
A15
A16
A17
A18
A19
A20
A21
A22
REMARKS
Adjust to place sound marker in trap
notch as in Fig. 4.
F I G .
FIG.2
F I G . 3 F I G . 4
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