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Problem
2.
Gauge tube filament wi 11 not I ight
when filament switch is toggled
(filament indicator I ight does
not light even momentarily).
_)'
Possible Cause
7. IC 10-A or associated component
defective. Using an oscilloscope,
verify that the waveform present on
pin I of IC I 0-A is as shown on Fig. 5-4
when the filament light is on.
8.
Verify that the waveform present
at the junction of R33 and CI O is as
shown on Fig. 5-3 when the filament
light is off. If not CR28, R33 or CIO
is defective.
9.
Attempt to turn on the filament
and check for pulses riding on the
above waveshape during the time the
filament light is on. If not present, check
QI I, Q 17 and associated components.
I 0. Defective triac SCR I or pulse
transformer TI. Using an oscilloscope
check for firing pulses on SCR l gate to
anode I (across C23) during period when
light is on. If pulses are present, the
triac is defective. If pulses are not
present, check for shorts across SCR I,
C23 or TI.
I I. Defective degas switch, S6, or 9 and I 0
of transformer, T4.
I. Incorrect input applied from remote input.
2.
Power supply voltage problem.
3.
Defective relay K3.
4.
Defective circuit components R2 I, R22,
C7, CRS, K3 or no input from
electrometer circuit.
Cure
Troubleshoot and repair
Troubleshoot and repair as
necessary.
Troubleshoot and repair as
necessary.
Troubleshoot and repair.
Troubleshoot and repair.
J
Correct source of remote input.
Must be momentary type of input.
Refer to Power Supply Problems.
Replace relay.
Troubleshoot and repair.
