The OSCILLATOR DRIVERalarm indicates that at least one
of the RF buffers is not operating properly. The alarm
could result from a failure in the RF buffer, in the
detection circuit on the RF buffer PWB (1A38,
1A39), a failure on the frequency synthesizer PWB
(1A2A2) 1A2A5) or in the alarm circuitry on the
system controller PWB.Trouble shoot an
OSCILLATOR DRIVER alarm as follows:
(a)Measure DC voltage at L1 of the RF drive
buffer PWB. If it is less than 48 volts, suspect
the dual regulated +48Vdc power supply (see
(b)Use an oscilloscope to look at the signal at E1 of
the RF buffer PWB.The signal should
approximate a square wave of approximately
30Vp-p. If signal is present, go to step (e).
(c)If no signal is present, check R1 of the RF
buffer PWB for a 15Vp-p square wave at the
carrier frequency. If present and there is +48
VDC at L1, +24 VDC at CR5 (cathode) and a
nominal +0.2 VDC at Q6 (collector), suspect the
RF buffer PWB (see figure SD-18).
(d)If no signal is present at R1, check R59 of the
frequency synthesizer PWB (1A2A2, 1A2A5)
for a 15Vp-p square wave. If no signal is
present, suspect the frequency synthesizer PWB
(see frequency synthesizer manual).
(e)Measure dc voltage at Q8 (collector) on the RF
buffer PWB. If approximately 0V, suspect the
alarm circuitry on the system controller PWB.
If approximately 5V, suspect the detection
circuitry (U1, Q8 and associated components)
on the RF buffer PWB (see figure SD-18).