GE 4PE350A3 Instructions Manual page 42

EBI-6351
COLOR CAMERA
6. The focus regulating voltage across R74
should not change more than 0.004 volt with
an eight percent change of focus coil re-
sistance.
7. There should be 60 volts ± 2.0 peak -to
peak of horizontal and vertical blanking. If
either or both horizontal and vertical drives
are removed, this output should go to zero.
The d -c component of the blanking should be
such that the black tips are set at the d -c
voltage applied to the blanking level pin on
the plug.
Skew Generator Board, PL -7781890
Refer to Figs. 37 through 39.
1. Check the +20 volt d -c power input
at pin 5.
2. Using an oscilloscope, check the verti-
cal sawtooth at the base of Ql.
3. Use the oscilloscope to make the fol-
lowing checks with the SKEW controls set to
one end of their range:
a. Check the W SKEW at pin H. It
should read 1.25 volts peak -to -peak.
b. Check the R SKEW at pin
7.
It
should read 1.25 volts peak -to -peak.
c. Check the B SKEW at pin 6. It should
read 1.25 volts peak -to -peak.
d. Check the G SKEW at pin 1. It should
read 1.25 volts peak -to -peak.
Camera Power Supply Board,
PL -7674504G2
Refer to Figs. 40 through 43.
The Camera power supply board is located
on the right-hand side of the Camera in the
upper right corner.
WARNING
LETHAL VOLTAGES ARE USED
ON THIS BOARD. EXTREME CARE
MUST BE EXERC13ED DURING AD-
JUSTMENTS.
1. Turn the METER SELECT switch to
+100. The meter pointer reads at mid -scale
on the red line. Failure to obtain this reading
indicates that the Camera power supply +100
28
volt d -c potentiometer (R20, located lower
right of center on the printed circuit board)
requires adjustment. Use a small, insulated
screwdriver until the meter pointer reads on
the red line.
2. Turn the METER SELECT switch to
+20. The meter pointer reads at mid -scale
on the red line. Failure to obtain this reading
indicates that the +20 volt d -c potentiometer
(R44, located lower left of center on the
printed circuit board) requires adjustment.
Use a small, insulated screwdriver until the
meter pointer reads on the red line.
3. The overload circuit is reset by R26,
which influences the threshold voltage used
to trigger unijunction Q10. Should overload
adjustment become necessary, proceed as
follows:
a. To recycle the supply, first turn it
off.
b. Turn the METER SELECT switch to
+100.
c. Using an insulated screwdrive..:, turn
R26 fully CW to ascertain a starting point.
d. Advance R26 CCW approximately 180
degrees.
e. Set the Camera POWER switch to ON.
f. Observe the viewfinder to see if the
raster returns and the +100 volts is present
at the meter. Failure to obtain the picture
and voltage indicates that R26 should be
advanced more CCW.
g. Cycle the Camera power off and on
and observe that the power supply remains
on. Arbitrary minor adjustments of R26 may
be made to cause triggering within a 30 -
degree span of the desired operating point.
h. If, after adjustment of R26, the over-
load still exists, the supply will not turn on
until the condition causing it has been cor-
rected.
Viewfinder Switcher Board, PL -7674431
Refer to Figs. 44 through 47.
1. Check the +20 volt d -c input at J8 -K.
2. Check the -20 volt d -c input at J8-8.
3. Check the auxiliary video input at J8-1.
It should read 0.7 volt ± 0.1 peak -to -peak.
4. Check the W (luminance) video input at
J8-2. It should read 0.7 volt ± 0.1 peak -to -
peak.