TEST
#5
CRT
BIAS
CIRCUITS
CAUTION
When you
make
any
of
the following tests, first turn
the Oscilloscope off. Then connect
th
e voltmeter
to
the circuit and turn the Oscilloscope
back
on again.
~)
~
Check
0301,
0302,
C301 , C302, and
T1
. Check
th
e
Check the voltage
at
the
junction
of
C301 and R301.
voltage
betw
ee
n A and B. It should
be
360
VAG.
It should read
-2
000
VOC.
h/
~E~
2>
Check C303 and R301. Check
for
open
or
shorted
Check the voltage at the junction
of
C303 and R301 . foils. Check
0316
,
0320,
and
0314
.
It
should read - 1650 VOC.
~
~
lfitislowerthan
- 1350VOC,check
0317
and
C320
.
Also check divider string R17, R6, R309,
and
R310
Check
the
voltage
at
A
E.
It should read - 1350 VOC.
for open and bad connections. If the voltage is
higher
Vi
than - 1350
VOC
, check for shorts in the
divider
~Ey
string, and check wires and foils.
~
Check the voltage
at
point W. It should read - 1568
Check
for
solder bridges and incorrect wiring
to
the
VOC.
~
CRT
socket. Also check C320.
~E7
~
Check the voltage
at
pointY
. It should read +
95
VOC. (Adjust it
if
necessary.) Check
0307
and associated circuitry.
~
CRT bias circuits are all operating properly.
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