8-15. Output Attenuator TestThis test checks the circuits in the signal path shown in figure 6-7. If the^previous tests haveteen performed, the only major circuits tested are two buffers, and the Adgnal is derived from-the DAC. It is fed through the Summing Junction, a frequencys b i i T n e t w o r k . a bufferrthe output attenuator, another buffer and finally, measured atthe VCO CoiSofVoltage Output with an -hp- 3455A voltmeter. The program selects allfour states of the attenuator. checking for the correct voltage readings f 5 0 , ? * e v 0 J m c t e / ° neach step. The user is given the option of discontinuing the test after the first reading if thetest appears to be failing. The program prints the results of the testInitializing the TestWith the High Frequency Menu displayed, press SFK K7 to initialize the test. After initialization, follow the instructions displayed on the computer.What if the Test Fails?Assuming that the DAC test passed, the only probable causes of failure are: one of tte buffers. the frequency shaping network, or the Attenuator. As in the DAC test, SWITCHT h e usedUo vary the output of the DAC. The signal should then be traced alongthepathshown in Figure 6-7 using a voltmeter or a scope. Refer to Service Group Three forschematics, component locators, and circuit descriptions.r i O 35601U %•]o o 1 1 34SS1 v1 (2NPUTWIRE)L%—S-C5 G -its-* IFigure 6-7. Output Attenuator TestOutput Attenuator Test6-19/6-20
