TM 11-6625-2735-14-1
Main Interface Board Removal.
If repair is necessary on
the reverse side of the Main Interface circuit-board, it may
be possible to gain access to that area by removal of one or
two circuit boards as outlined previously. Consider this
first or proceed with the Main Interface board removal
procedure.
The Main Interface circuit-board can be removed as
follows:
1. Remove the Vertical Preamp circuit-board as outlin-
ed previously.
2. Remove the Trigger Generator and Z-Axis Logic
board as outlined previously.
3. Remove the high-voltage shield and remove the
Vertical Output circuit-board shield (if installed).
4. Remove the BEAM FINDER and X10 MAG pushbut-
ton extension-shafts. Insert a scribe or small screwdriver
between the end of the white plastic switch-shaft and the
inside end of the black plastic extension-shaft and pry
gently.
5. Remove the INTENSITY, FOCUS, SCALE ILLUM,
ASTIG and TRACE ROTATION control extension-shafts.
Loosen the front setscrew in each coupling with a 0.050-
inch Allen wrench.
6. Disconnnect twelve ribbon or wire cable-
connectors from the Main Interface circuit-board and
confirm the number and color of wires for each plug and
its location in the following list.
a. Disconnect one-wire from pin E at the top-left of the
board.
b. Disconnect a two-wire cable from pins B and C at
the top-left of the board.
c. Disconnect a two-wire cable near the rear of the
intensity control (cable from the y-axis alignment coil).
d. Disconnect a two-wire cable near Q1482 (cable
from the graticule lamps).
e. Disconnect a four-wire cable at the right-center of
the board (cable from POSITION and FINE controls).
f. Disconnect a four-wire cable at the rear of the A
TRIG HOLDOFF control (cable from the DELAY TIME
POSITION control).
g. Disconnect a
two-wire cable from the
Calibrator current loop.
h. Disconnect four, two-wire cables near F1318 at the
bottom-left of the board. The cable wires to +15 are red
with a brown stripe. The cable wires to –15 are violet with a
brown stripe. Cable wires to the pins nearest the fuse
(GND) are black. Cable wires to the remaining pins are red
with a black stripe.
7. Disconnect two coaxial-cables from the left-center
of the board. The cable to J1302 is white with a gray stripe
and the cable to J1334 is white with black and orange
stripes.
8. Disconnect the horizontal deflection plate leads at
the crt. This requires a pair of long-nose pliers or tweezers
for best removal or reinstallation.
9. Disconnect a three-wire cable from the Vertical
Output board.
10. Disconnect a two-wire cable from the Fan Motor
board.
11. Unsolder a 10-ohm, 1/2 watt resistor from the
center-tap terminal of the ceramic thick-film resistor
mounted near the Vertical Output circuit-board.
12. Unsolder ten wires from the Main interface circuit-
board and confirm each wire color with its location in the
following list (all wires from crt socket).
a. Wire to pad 5 is white with a green stripe.
b. Wire to pad 10 is white with black and brown stripes.
c. Wire to pad 7 is white with a violet stripe.
d. Wire to pad 8 is white with a gray stripe.
e. Wire to the one-notch ceramic-strip is white with a
yellow stripe.
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