Sect. IV Page 20 Model 618B
TABLE 4- , PULSER TROUBLE SHOOTING CHART (CONT?D.)
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Check and Symptom Possible Cause Remedy
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4. Check pulse at DELAYED SYNC OUT jack. This check tests delayed sync out V115,
pulse delay V107, amplifiers V105B and V109A and couplin diode- V106.
Poor DELAYED SYNC Replace V105 or V109 without
output pulse shape: Defective V115 or V109B. further adjustment.
Inadequate delay time: Out of adjustment or defective Adjust pulse delay as described
V107. in para. 4-18.
No output pulse: Defective V106, V107, V109, Replace V106, V107, V.109 or
or V115. V115, make adjustments as required.
5. Check rf output pulse. This check tests the remaining pulser circuit
pulse length multivibrator V111.
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Inadequate pulse length: Out of adjustment or defective Adjust pulse length as described
v111. in para. 4-19.
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No rf output pulse: Defective V101, V102.
4-17 CALIBRATING THE PULSE RATE DIAL 5) Adjust the amplitude controls on the oscillo-
scope to obtain a convenient scope presentation.
Replacing V103 may lessen the accuracy of the
PULSE RATE dial, but will not otherwise affect
the performance of the signal generator. It should
6) Set the oscillator to 4000 cps.
be noted, however, that the calibration of this dial
is only approximate.
7) Adjust the sweep rate of the oscilloscope so
that several cycles of sine wave occupy the full
To calibrate the PULSE RATE dial, proceed as width of the screen.
follows:
1) Connect SYNC OUT connector to the SYNC 8) Adjust R112, Figure 4-13, so that thegenerated
input of an oscilloscope. pulse rate is 4000 pps. When the repetition rate
of the pulses is 4000 pps, eachpulsewill be super-
2) Connect DELAYED SYNC OUT connector to imposed upon each cycle of the sine wave. Adjust
the oscilloscope vertical amplifier input. R112 until the pattern is stationary and all slope
is removed (top of pulses in a straight, horizon-
tal line).
3) Connect the output of a calibrated audio oscil-
lator to the oscilloscope vertical amplifier input
9) Set the SYNC SELECTOR to X1 with the other
through a 10,000 ohm isolating resistor.
controls remaining unchanged. Set oscillator
to 400 cps.
4) Set the MOD. SELECTOR switch to INT. and
the pulse rate to 4000 pps (SYNC SELECTOR 10) Adjust R113 so that the generated pulse rate
switch to X10 and PULSE RATE control to400). is 400 pps. |
ACEC
