Model 130B Sect.IV Page 11
B. HIGH VOLTAGE SUPP Y 4) With a screwdriver loosen the crt base from
-
socket. Free the crt from the socket by pressing
\
I 1) The -2550 volt output is measured on there- on the center of the tube base with one hand while
sistor board under the base of the crt. Connect supporting the front of the crt with the other.
an appropriate dc voltmeter (such as an @ Model
DANGER - Do not apply force on neck of tube.
410B VTVM with an @ Model 459A DC Resistive
Voltage Multiplier) to the Junction of R338, C312
5) Remove the crt through the front panel.
(marked -2550 CATH. on cover).
CAUTION - HANDLE THE CATHODE RAY TUBE
2) With the line at 115/230 volts the high voltage CAREFULLY.
should measure -2550 *4%. Control R334 can
be adjusted if necessary to set the -2550 volt 6) Insert the replacement crt through the front
supply within limits. panel and seat in socket.
If poor -2550 voltage supply regulation is sus- 7) Replace front-panel bezel.
pected the following check may be made:
8) Adjust the socket assembly so that the face of
-- Check the regulation by varying the line volt-
the crt just misses the bezel assembly. Tighten the
age between 103 and 127 volts. The -2550
clamp just enough to hold the crt in place loosely.
should remain within ~tl% over this range of
line voltage. If the -2550 supply does not regu-
NOTE
late check the control tube V312.
Turn the INTENSITY control to minimum when
3) Set SWEEP TIME/CM to 5 MILLISECONDS. first applying power to a crt. The phosphor can
be damaged quickly by too much brightness.
------------
4) Set HOR. SENS. to INT. SWEEP X1.
5) Set SWEEP MODE fully clockwise to FREE 9) Set the INTENSITY control fully counterclock-
RUN. wise. Turn the 130B on and allow to warm up.
6) Set INTENSITY control to 10 o?clock. 10)Set the SWEEP MODE control to FREE RUN.
7) Set Int. Adj., R343, until the trace is just 11) Adjust the INTENSITY control to obtain a
visible. weak trace; adjust the FOCUS control for a sharp
trace, and with the vertical position control,
8) Set SWEEP MODE fully counterclockwise to center the trace vertically.
PRESET.
12) Align trace with graticule using the alignment
9) Set INTENSITY control for a low intensityspot. handle at rear of crt.
CAUTION - Do not over-tighten crt clamp or
10)Center spot and adjust FOCUS control and
tube damage may result.
ASTIGMATISM (R303) to obtain a small round and
sharply focused spot.
13)Making certain the crt face is close to but not
touching the bezel assembly, tighten the clamp
on the crt socket only enough to hold the crt from
turning. If the face of the tube touches the bezel
4-11 REPLACING AND ADJUSTING THE CRT
assembly, Newton rings may be visible.
To replace the cathode-ray tube, refer to Figure
2-10, and proceed as follows: 14) Readjust the astigmatism; see paragraph 4-10B.
1) Turn off and remove the 130B from thecabinet. 15) Check the gain calibration of the Vertical and
Horizontal Amplifiers by setting the VERTICAL
2) Loosen the clamp on the crt socket. (Cabinet and HORIZONTAL SENSITIVITY selectors to CAL,
model; remove cover from High Voltage terminal and if necessary, adjusting R40 (Figure 4-5) to
board to get access for screwdriver through board). obtain 6 cm vertical deflection and R144 (Figure
4-6) to obtain 6 cm horizontal deflection on the
3) Remove the front-panel bezel. trace; see paragraph 4-13B and 4-14R. |
ACEC
