Maintenance—2246 1Y and 2246 Mod A Service
5. Remove rear crt shield (held in place by 3 self
tapping screw s),
6. Place your left hand on crt neck shield and your
right hand over crt face. Move the crt and neck
shield assembly forward to unplug the crt
f r o m
its socket and carefully withdraw it from the in
strument, feeding the trace rotation cable and
anode lead through their respective access
holes in the crt front shield. Do not hold the crt
assembly by the neck shield only.
7. If it is necessary remove the metal neck shield
from crt. Carefully slide the shield to rear of the
crt. Be careful not to damage the neck pins.
To install the crt:
8. Install the metal shield over the neck of the crt.
Make sure that the plastic grommet is in place
over the front of the shield. Align the neck pins
with the shield holes.
9. Check that the graticule scale-illumination light
pipe is in place at bottom front of crt opening.
Also make sure that the four crt corner cushions
are in place in the crt opening of the subpanel.
10. Carefully guide the crt, anode lead, and trace
rotation cable into the instrument and through
the access holes in the crt shield. Line up the crt
base pins with base socket. Make sure that the
ground clip above the rear of the crt shield goes
outside of the shield. Hold in on the rear of the
base socket with one hand and push on the face
of the crt with the other hand to completely seat
the crt base pins. If the crt will not go in all the
way, check for bent pins. DO NOT FORCE this
connection!
11. Connect the trace rotation cable (P27) to the
Main board.
12. Connect the vertical and horizontal deflection
leads to the crt neck pins. The horizontal de
flection leads (going to bottom pins) should be
crossed.
13. Connect the high-voltage anode lead.
14. Install the crt implosion shield and frame using
two 7/8 in. Torx-head screws.
15. Check that the graticule illumination light bulbs
are in place in the light pipe at the bottom of the
crt.
16. Reinstall rear crt shield.
BNC Connectors (Vertical Inputs)
To replace BNC Connectors:
1. Remove the Main board (see Main board
removal procedure).
N O T E
D o n o t d is c o n n e c t th e e n d s o f th e d e la y lin e
fr o m b o a r d a s in d ic a t e d in th e M a in b o a r d
r e m o v a l p r o c e d u r e . It Is n o t n e c e s s a r y fo r
r e p la c in g th e in p u t B N C c o n n e c to r s .
2. Unsolder the input lead of the defective BNC
connector(s).
3. Using a 9/16 open-end wrench, remove and
replace the defective BNC connector(s).
4. Resolder the input lead(s).
5. Replace the Main board (see Main board instal
lation procedure).
A16 Processor Board
To remove the Processor board:
1. Unplug ribbon cables P2501, P2502, P2302, and
P2304 from the the processor board. To aid the
release of the ribbon-cable pins from con
nector, slide a thin-shafted, flat-bladed screw
driver between the ribbon cable (near the
connector) and the etched-circuit board and pry
gently upward.
2. Remove the six Torx-head attaching screws
(one at each corner and two in the middle).
3. Unplug P2105 (17-pin) from the Potentiometer
board and lift the Processor board out of the
instrument.
To install the Processor board:
r ^ A A A A / V W \ < n
> CAUTION |
C v w w w v rS
Do
n o t e x c e e d 9 i n - l b o f to r q u e w h e n t ig h te n
in g th e 6 - 3 2 s c r e w s t h a t h o ld th e c ir c u it
b o a r d to th e c h a s s is . D a m a g e to th e c ir c u it
b o a r d a n d l o r s c r e w t h r e a d s m a y r e s u lt i f th e
s c r e w s a re o v e r t ig h t e n e d .
6-40
Summary of Contents for 2246 1Y
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