TB 9-6625-2139-35
b. Adjustments
(1) Disconnect oscilloscope calibrator and 50Ω feedthrough termination from TI.
(2) Position controls as listed in (a) through (o) below:
(a) POSITION controls to midrange.
(b) VERTICAL MODE CH 1 BOTH CH 2 switch to BOTH.
(c) VERTICAL MODE TRIGGER SOURCE CH 1 pushbutton to out position
(AN/USM-488).
(d) VERTICAL MODE TRIGGER SOURCE CH 2 pushbutton to in position
(AN/USM-488).
(e) VERTICAL MODE ADD ALT CHOP switch to ALT.
(f) CH 1 and CH 2 VOLTS/DIV switches to .5.
(g) CH 1 and CH 2 AC GND DC switches to GND.
(h) HORIZONTAL MODE switch to A.
(i) A AND B SEC/DIV switches to 1 ms.
(j) B TRIGGER SLOPE to OUT:
(k) B TRIGGER LEVEL control to midrange.
(l) A TRIGGER P-P AUTO pushbutton pressed.
(m) A TRIGGER SLOPE pushbutton to OUT:
(n) A TRIGGER LEVEL control to midrange.
(o) A TRIGGER A&B INT switch to CH 2 (type 2235).
(3) Adjust CH 1 and CH 2 POSITION controls to set both traces to the center
horizontal graticule line.
(4) Connect digital multimeter LO to chassis ground and HI to pin 1 on A5 (fig. 1)
board connector. Digital multimeter indication will be less than 100 mV dc. Record digital
multimeter indication.
(5) Position controls as listed in (a) through (c) below:
(a) VERTICAL MODE TRIGGER SOURCE CH 1 pushbutton to in position
(AN/ USM-488).
(b) VERTICAL MODE TRIGGER SOURCE CH 2 pushbutton to out position
(AN/ USM-488).
(c) A TRIGGER A&B INT switch to CH 1 (type 2235).
(6) Adjust R309 (fig. 1) for digital multimeter indication recorded in (4) above.
(7) Position controls as listed in (a) through (c) below:
(a) VERTICAL MODE TRIGGER SOURCE CH 1 pushbutton to out position
(AN/USM-488).
(b) VERTICAL MODE TRIGGER SOURCE CH 2 pushbutton to in position
(AN/USM-488).
(c) A TRIGGER A&B INT switch to CH 2 (type 2235).
(8) Repeat (4) through (7) above until digital multimeter indications in (4) and (6)
above are equal within 1 mV dc.
(9) Disconnect digital multimeter.
(10) Position controls as listed in (a) through (g) below:
(a) VERTICAL MODE CH 1 BOTH CH 2 switch to CH 1.
(b) VERTICAL MODE TRIGGER SOURCE CH 1 pushbutton to in position
(AN/USM-488).
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