the Television Analyst. The scan will not necessarily be linear
but provides an excellent test on the vertical output transformer
and yoke. Disconnect the Plate Drive test lead and reinsert the
vertical output tube in the test receiver. Turn the Plate nrive
Selector switch to the "OFF" position.
24. Disconnect the leads of the vertical winding of the deflection yoke
of the test receiver. Connect one lead to ground on the Analyst and
the other lead to the Vertical Yoke Test Signal jack on the Tele
vision Analyst. Turn on the test receiver. Vertical Scan will be
seen on the test receiver. While not linear in deflection it proves
that the vertical yoke will provide deflection. Remove test leads
and reconnect vertical yoke leads to the test receiver.
25. To test a transformer for shorted turns connect the shielded cable
to the Flyback-Yoke test signal jack. Adjust the Calibrate control
until the test indicator lamp just goes out. Connect the flyback
transformer to this cable. The connection is made from horizontal
output plate cap connector to hi voltage rectifier plate cap connector.
If the test indicator glows this indicates that the transformer has
shorted turns. This test will respond to as little as one shorted turn.
If the component to be tested is the horizontal winding of the de
flection yoke, connection is made across the deflection yoke winding.
It is also important to test the yoke for leakage between the vertical
and horizontal winding and from the horizontal to the metal frame
of the yoke. Do not use the yoke test on the vertical winding, as
erroneous results will be obtained.
26. To observe the action of the Negative Bias Supply, connect the
Television Analyst to obtain a picture on the test receiver. Connect
a ground lead from the Television Analyst to the test receiver and
connect a test lead from the Negative Bias supply output jack to
the A.G.C. buss of the test receiver video I.F. stages. Set the R.F.
Attenuator of the Analyst to number .10, maximum R.F. output.
Since the bias supply is very low impedance it will take over control
from the high impedance A.G.C. system. In other words, the A.G.C.
bias being fed back from the A.G.C. network is completely overcome
by the bias voltage we are feeding in from our supply. We can
now control the A.G.C. bias and therefore the test receiver gain.
Adjusting the bias supply varies the receiver gain. With the bias
supply set to -50 volts the receiver will be cut off and no picture
will be seen. As the negative bias supply voltage is reduced a picture
will become visible. Most receivers will begin to show a picture
in the region --6 to -12 volts. As the bias voltage is reduced
even further the picture will begin to overload. This will usually
show up as snaking in the picture due to sync clipping. If the
bias is reduced even further the picture will get blacker and then
will reverse phase and then completely disappear at zero bias, in
dicating complete blocking of the receiver. Disconnect the bias test
leads and restore the test receiver to normal operation.
27. Connect the R.F. output of the Analyst to the R.F. antenna terminals
of a color TV receiver. Tune the receiver to an unused TV channel
tune the Analyst to that same channel as described above. With
the black and white test pattern showing, on the Color TV screen,
turn the Color Switch to "On". This will switch on the 3.58 me
color rainbow generator signal. This signal will produce a color
spectrum. The color sequence of the spectrum is as follows: Reddish
Orange at the extreme left side of the tube, followed by a gradual
transition to Red, Magenta, Blue, Cyan and Green at the right side
of the tube. This color rainbow signal can be used to isolate defective
stages in the color section of the color TV receiver. This chroma
signal can also be fed into the I.F .. section. By taking the color
signal from the 3.5 me color jack it can be fed directly into the
video and chroma sections.
13
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