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Adv anced Systems T ester 900AST Series Coaxial W ire T esting T echnical T ip December 2005 78-8135-6156-6-A.
3M ™ Advanced Systems T ester 900AST Ser ies 2 Setup f or Use Battery Requirement The battery holder holds six “ AA” standard alkaline batteries and should be installed prior to using the unit. Please see the 900AST tester manual or D VD for battery installation instructions.
3M ™ Advanced Systems T ester 900AST Ser ies 3 Ke ypad The 900AST tester ke ypad has twelve yello w and red “Control K eys” and nine blue “Function K eys”. Additional blue ke ys on the keypad are reserv ed for future expansion and ha ve no designation or current function.
3M ™ Advanced Systems T ester 900AST Ser ies 4 Contrast and Backlighting Note: Use of backlight decreases available battery capacity . Pre ss the k e y t o d ispl ay the co ntr ast scr een . Use the and ke ys to adj ust the con tra st. Press the ke y aga in to turn the back lig ht on or of f.
3M ™ Advanced Systems T ester 900AST Ser ies 5 Use the [RFL] ke y to find the distance to a resistance fault between two conductors or a conductor and ground. This ke y is used for editing only . Use the [TDR] ke y to activ ate the T ime Domain Reflectometer .
3M ™ Advanced Systems T ester 900AST Ser ies 6 TDR Setup The TDR features a setup function that allo ws you to select the type of Coaxial wire to be tested. From the TDR Menu, press the Setup ke y to enter the TDR Setup. Press the select key and the and arrow ke ys to highlight coaxial cable for wire type.
3M ™ Advanced Systems T ester 900AST Ser ies 7 TDR T est Modes Press the or keys to mov e to the desired mode. Press the key to accept the highlighted mode and start the measurement. Single T race Use the TDR Single Trace mode to test a single coaxial wire or circuit.
3M ™ Advanced Systems T ester 900AST Ser ies 8 Dual T race Dua l T race is us ed to com pare tw o co axia l c irc uit s a t the sa me tim e (u sua lly a fa ult ed a nd a g ood ci rcui t). Connect the TDR test leads to the (Red and Black jacks) and connect the second TDR test lead set (Blue and Y ellow jacks) to the reference circuit.
3M ™ Advanced Systems T ester 900AST Ser ies 9 Use the and ke ys to highlight the desired stored result. Press the key to display the stored trace on the bottom of the TDR screen and the “li ve” trace on the top. Y ou may move the cursor by using the and ke ys.
3M ™ Advanced Systems T ester 900AST Ser ies 10 Length allo ws you to set the distance (or span) from the left side of the screen to the right side. The left side of the screen is at the end of the .
3M ™ Advanced Systems T ester 900AST Ser ies 11 Press the key . The 900AST tester will display the Sav e Results screen as follo ws: Use the blue keys to enter an alphanumeric ID. The ID may hav e up to twelve digits. Whether a number or letter is entered depends on how many times the ke y is pressed.
3M ™ Advanced Systems T ester 900AST Ser ies 12 generally cause small upward peaks due to a change in impedance. T o determine if an upward e vent is an impedance change or a main e vent fault you may go to the other end of the coaxial cable and disconnect it.
3M ™ Advanced Systems T ester 900AST Ser ies 13 Short Circuit A short circuit (or zero-Ohm resistance fault) will sho w up as the lowest dip on the screen. Y ou cannot see e vents past a short circuit Branch Circuit The beginning of the branch circuit will look lik e a small dip and the end of the branch will look like an open (upward peak).
3M ™ Advanced Systems T ester 900AST Ser ies 14 Connect the 900AST test leads to the coaxial conductor under test. Press the ke y to access the Soak test from the Resistance screen. Use the ke y to save the activ e resistance to the “Snap Shot” area.
3M ™ Advanced Systems T ester 900AST Ser ies 15 T o change the coaxial configuration go to the TDR function and press the Setup key . Use the and ke ys and the Blue numeric ke ys to enter the length of cable to analyze. Enter a length longer than the cable being tested but as close as possible to the total length of the cable.
3M ™ Advanced Systems T ester 900AST Ser ies 16 In this case the low impedance anomaly at 24 inches is detected but not classified. The Auto TDR displays ‘????’ below the trace. Restoring the Aircraft After T esting/ T roubleshooting Disconnect the 900AST TDR test cable from the aircraft wiring.
3M ™ Advanced Systems T ester 900AST Ser ies 17 Aer ospace and Aircra ft Maintenan ce Division T rans portatio n Business 3M Center , Buildin g 220-9W -14 St. Paul, MN 55144-10 00 1-800-3 64-3577 or 651-737 -6501 www .3M.co m/aerospa ce © 3M 2005 78-8135 -6156-6- A 3M is a trademark of 3M Company .
