B&K 1076, Instruction Manual

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me I.F. frequencies. You will notice that when you tune to the
correct I.F. frequency you will again see the test pattern and hear
the tone on the monitor receiver. Tune for best picture and sound.
14. Move the R.F.-1.F. output cable from the first I.F. to the grid and
plate of the second I.F. and then to the grid and. plate of the third
I.F. tubes and notice how the reproduced video signal on the monitor
screen becomes weaker and weaker. This is an effective way of
determining whether an I.F. stage is contributing gain to the overall
I.F. amplifier system. Notice that with only one I.F. stage, the last
I.F. stage, being used there is still enough gain to reproduce the
complete test pattern on the monitor receiver. In going through
the I.F. stages, it must be noted that the R.F. Attenuator Control
also controls the output· level of the I.F. signals from the Television
Analyst. Turn the audio selector switch to "Off" and remove the
R.F. cable from the monitor receiver.
15. Using the test leads provided, connect the Ground Jack on the
Analyst to the chassis ground or
B-
of the monitor receiver. Connect
the Video output jack of the Analyst to the video detector load
resistor of the receiver. This load can usually be found very easily
by lookin; for the peaking coils associated with this video detector
circuit. You will now see the complete test pattern once again, iI
the video signal is of the right polarity. If the picture is negative,
reverse the polarity of the Video Polarity (
+
or -) switch.
If
there is more than one video amplifier stage in the monitor receiver,
the signal can be injected into the grid of the second video amplifier
and the test pattern can again be reproduced. It will be necessary
to reverse the polarity of the video polarity switch because the polar­
ity of the· signal is reversed in going through each amplifier stage.
Remove the video output c:,,hle from the monitor receiver.
16. Connect the ground jack on the Television Analyst to the· chassis
ground, or
B-
of the monitor receiver. Connect a second test
lead to the sync jack of the Television Analyst and inject this signal
to the grid or cathode of the picture tube of the monitor receiver.
Select the element which receives video modulation. Rotate the ampli­
tude control to +50 volts and observe black and white bars running out
of sync on the monitor receiver. Rotate the sync amplitude control
to the -50 volt position, notice that the phase of the modulation
on the monitor receiver changes. This signal is used to determine
whether or not a picture tube will �ccept video modulation. Restore
receiver to normal operation.
17. Turn the Audio Switch to "Tone" position and connect the appro­
priate test leads from the 4.5 me Audio I.F. Output jack of the
Analyst to the grid of the first audio I.F. (4.5 me) amplifier. You
will now hear the audio signal in the sound system of the TV
receiver. Move this signal to the grid of the video amplifier and
the tone will still be heard. To verify this signal, turn the Audio
Switch to the "Off" position and see if the sound in the monitor
speaker disappears.
18. Connect a ground lead of the Television Analyst to ground, or
B­
on the monitor receiver. Remove a sync amplifier tube from the
monitor receiver.
If
this is a series string set, short out the heater
pins in the socket of the tube just removed. This permits the re­
mainder of the receiver to operate normally. Connect a second test
lead to the Sync jack of the Analyst. Inject this signal to the plate
of the socket of the tube just removed. Rotate the sync amplitude
control to +50 volts.
If
this sync signal is of the proper phase, the
picture on the monitor receiver will be properly in sync.
If
the
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