TABLE OF CONTENTS 



Page 



INITIAL ALIGNMENT ......... 



O u * If 



AMPLIFIER CHANNELS ....... ........ ...... -L 



Description^, • «.....«.......<>.«..»< J. 



Self -noise Measurements . ..#.......*..-«.. 2 



120B Amplifier „. «.».....<.. ....... .o 4 



Input and Output Noise Voltages of. 120B Amplifier,, . . 5 



121A Amplifier ..................... 6 



OBPVXCXngo o.»...o..o. .•.••.•.•*«« O 



' Gain and Undistorted Output Measurements .„«..... 6 



Channel Amplifier Power Supplies ............ 7 



TIME TONS AMPLIFIER ,..„.. ........ ....»•. 8 



Description^ ...... ».«... .•..»,«».•»« 8 



oervicing*. .......o. .«.'.. ...... ..jo v 



MONITOR AMPLIFIER AND LOUD-SPEAKER. ........... a 9 



AUTOMATIC SWITCHING UNIT, ................. 10 



Sensitivity Adjust/Dent gagaa..***-.****,© 11 



it© 3 6 Ti TJXH&& »»c »> o o o 9e « o o o o w«»ti^j»oa o XX 



Servicing o »•»••* »^« *«•«■*•• o • o o »••• » xx 



GRAPHIC LEVEL RECORDERS .a'..'.............. 12 



Description^, ........a........'. .... -*•<<- 



Explanation of Operation ...... ....»o..oo 12 



Speed Controls „..<>. ........... ..... 13 



Inserting Paper Tape ............ »..».» 14 



Protective Relay » . ....... ..«••••..«. 14 



Changing the Signal Input Potentiometer. ........ 14 



Switch Box and Amplifier ................ 15 



Sensitivity Adjustment ................. 15 



Checking for Erratic Behavior. ...... ...... . 15 



Maintenance . ......oo..... .»♦.».••-. 16 



Basic Construction and Operation ............ 16 



TIME INDEXING MECHANISM ,.....,.„ ........ „ 17 



Recorder as Received ....... .««.». »«.<;. 18 



Altered Recorder ...... ...... «<>«.«o.o 18 



Timing Stylus Mechanism. ...... .......... 18 



Bottom View. SO o.oo. .o. •*.«<>... ...ao 18 



End View .o.oo.......o.°<..<>o.°.°° iV . 



