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BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
A
737-300/400/500MAINTENANCE MANUAL
B. Special Tools and Equipment
(1) Tektronix 1502B - Time Domain Reflectometer
C. References
(1)
Wiring Diagram Manual
(2)
AMM 20-10-07/201, Rack-Mounted Electrical/Electronic Module
D. Access
(1) Location Zone
117/118 Electrical and Electronics Compartment
E. Procedure
S 862-011
(1) Prepare the applicable cable and the TDR (Fig. 201):
(a)
Pull the POWER button to the ON position.
(b)
Connect an adapter cable to the BNC on the front panel of the TDR.
(c)
Remove the black box at one end of the applicable cable (AMM 20-10-07/201).
(d)
Disconnect the applicable cable at the other end.
CAUTION:_______DO NOT DIRECTLY TOUCH THE RACK CONNECTORS. THIS CAN CAUSE DAMAGE. USE A BREAKOUT BOX.
(e)
Attach a breakout box to the rack connector were the black box was installed.
CAUTION: DO NOT ATTACH LIVE CIRCUIT CABLES TO THE INPUT OF THE TDR.
_______ VOLTAGES MORE THAN 5 VOLTS CAN CAUSE DAMAGE TO THE SAMPLING GATE OR TUNNEL DIODE.
(f)
Connect the adapter cable from the TDR to the applicable test points on the breakout box.
(g)
Connect a 50 ohm terminator to the open end of the applicable cable.
(h)
Set the NOISE FILTER on the TDR to 1 avg.
(i)
Set the VERT SCALE to 500 mp.
(j)
Set the DIST/DIV switch to show the full cable length.
NOTE: For example, for a 20 foot cable it will be necessary
____ to have 4 divisions on the display if you use 5 ft/DIV. If you do not know the cable length, set the DIST/DIV to 200 ft/DIV and continue to decrease the DIST/DIV until you see the full waveform. With a 50 ohm terminator attached, the applicable cable will show as a length of no limit.
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20-10-72
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BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
A
737-300/400/500
MAINTENANCE MANUAL
DISTANCE FROMLIQUID START OF CABLECRYSTAL
CURSOR TO CURSOR
DISPLAY
CABLE COEFFICIENT OF VP VALUE CONNECTION TDR FRONT PANEL
Time Domain Reflectometer Controls
Figure 201
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BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
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A
737-300/400/500MAINTENANCE MANUAL
(k) Set the Vp controls for the applicable cable.
NOTE: The left control is the first number and the right
____ control is the second number of the Vp value.
(l) Make allowance for the adapter cable and breakout box.
1) Measure the distance from the BNC on the TDR to the start of the applicable cable.
NOTE: This is the length of the adapter cable.
____
2) Turn the NOISE FILTER control to HORZ SET REF. 3) Turn the <>POSITION control to move the cursor until the
distance shown is equal to the adapter cable length. 4) Push STORE. 5) Turn the NOISE FILTER control to 1 avg. 6) Make sure you see 0.000ft. on the LCD.
NOTE: This is the start of the applicable cable.
____
S 282-012
(2) Examine the applicable cable (Fig. 202):
(a)
Examine the waveform shown on the LCD.
(b)
Make sure you have a straight line waveform equal to the length of the applicable cable (if known).
(c)
If it is necessary, turn the NOISE FILTER clockwise to average-out some of the noise.
NOTE: This will increase the time necessary for the TDR to
____
give a waveform output.
(d)
Make sure these failure conditions do not show: 1) A drop in the waveform, this shows a short circuit in the applicable cable. 2) A rise in the waveform, this shows an open circuit in the appplicable cable.
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