eXact 240 - Page 26

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240-0664
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SECTlON I I I -----------~------------------------------------ CALIBRATION
3.2.5 FIN AL TIMING (CONTINUED)
(G) OBSERVE THE AMOUNT OF ERROR AT THIS END OF THE DIAL.
LOOSEN THE SET SCREW AND MECHANICALLY SHIFT THE DIAL TO
COMPENSATE FOR THE ERROR.
LOCK.
S NUB THE SET SCREW BUT DO NOT
NOTE:
R116 (CYCLES/ S EC VARIABLE RESISTOR) IS VERY SENSI-
TIVE AT THE X1 END, THEREFORE CARE MUST BE TAKEN
WHEN THIS SETTING IS MADE.
(H) ADJUST THE CYCLES/SEC DIAL OF THE FUNCTION GENERATOR
TOWARD X10 UNTIL 10 TRIANGLES APPEAR FOR 10 CM OF SWEEP
ON THE OSCILLOSCOPE.
(J) OBSERVE THE AMOUNT OF ERROR AT THIS END OF THE DIAL.
IF
THERE IS LESS THAN 2 % , LOCK THE SET SCREWS.
(K) SET THE OSCILLOSCOPE SWEEP TIMING TO 100µsEc, THE FUNCTION
GENERATOR MULTIPLIER SWITCH TO 1000 ANO THE CYCLES/SEC DIAL
TO X1.
(L) ADJUST 1000 CYCLES TIMING CAPACITOR C102A FOR 1 TRIANGLE
IN 10 CM OF OSCILLOSCOPE SWEEP.
(M) SET THE FUNCTION GENERATOR CYCLES/SEC DIAL TO X10. ADJUST
HIGH FREQUENCY COMPENSATION TRIMMER CAPACITOR C103 FOR 10
TRIANGLES IN 10 CM OF OSCILLOSCOPE SWEEP.
(N) REPEAT (K), (L) AND (M) AS NECESSARY SO THAT BOTH ENDS OF
THE DIAL ARE ACCURATE.
3.2.6 FINAL FUNCTION GENERATCR TIMING CHECK
(A) HIGH FREQUENCY TIMING CHECK
(1) SET THE osc1LLOSCOPE S W EEP TIMING TO 10µsEc, THE
FUNCTION GENERATOR MULTIPLIER SWITCH TO 1000 AND THE
CYCLES/SEC DIAL TO X10.
(2) VERIFY THAT THE FUNCTION GENERATOR IS CORRECTLY TIMED
AT 10,000 CYCLES PER SECOND BY OBSERVING ONE CYCLE OF
THE TRIANGLE WAVEFORM FOR 10 CM OF SWEEP ON THE OSCIL-
LOSCOPE.
(3) SET THE osc1LLOSCOPE SW EEP TIMING To 100µsEc/cM, THE
FUNCTION GENERATOR MULTIPLIER SWITCH TO 1000, AND THE
CYCLES/SEC DIAL TO X1.
(4) VERIFY THAT THE FUNCTION GENERATOR IS CORRECTLY TIMED
AT 1000 CYCLES PER SECOND BY OBSERVING ONE CYCLE OF
THE TRIANGLE WAVEFORM FOR 10 CM OF SWEEP ON THE OSCIL-
LOSCOPE.