ESI 250-DA - Troubleshooting Chart for Oscillator and Output Issues

SYMPTOM
PROBABLE
CAUSE PROCEDURE
Failure
to
oscillate
Defective
tube
Replace 1ZAT7
No
plate
voltage Check
power supply; see
above.
Check resistor
R,
replace
if defect-
149
ive
Defective
plug-in oscil-
lator
unit
Check values of all com-
ponents in plug-in unit;
replace any
defective
ones
Check
for possible shorts
in plug-in unit
Failure
to
amplify
oscillator
signal
Defective
tube
Open
cathode
circuit
Replace 12AT7
Check
replace
if
defective
Defective
input
circuit
Check R,
Cl
»
C, ,
_
and
1
D
1
1 1 j
control potentiometer
^150*
defect-
ive
component
No
plate
voltage
Check
power supply; see
above
Check continuity of pri-
mary winding of T^^;
re-
place if
necessary
No
generator
output
Defective
coupling trans-
former
Check continuity
of secon-
dary
of Tj
and
associated
wiring; replace trans-
former if
necessary
Output
signal
off
fre-
quency
Oscillator
network
out
of
adjustment
Readjust
to
give cor-
rect
frequency