Model 130B Sect.IV Page 3
1) Leaving the VERT. SENSITIVITY switch in plates has unbalanced voltages, or if the position
CAL, switch HORIZ. SENSITIVITY switch to INT. control must be turned far from its mechanical
) SWEEPX1. center to balance these voltages, look for trouble
in that amplifier. If both sets of deflection plates
2) Switch SWEEP TIME/CM switch to 1 MILLI- have unusual voltages, look for trouble in the
SECOND. A six centimeter square-wave pattern power supply.
should appear on the screen. If no pattern is ob-
tained be sure SWEEP MODE is in PRESET, SYNC 5) If the series heater string should open, all
switch is in INT., and adjust TRIGGER LEVEL major sections will be inoperative.
to trigger. If a pattern cannot be obtained, the
malfunction is most likely in the Sweep Generator. 6) The two sides of the direct-coupled differential
amplifier, such as are used in the Vertical and
Horizontal Amplifiers on the: 130B, are balanced
and, unless a signal is present, the spot will be
4-3 REMOVING THE CABINET motionless in the center of the screen. Any signal,
In the cabinet model, remove the two screws at whether this signal is applied to the input terminals
the rear of the cabinet, and push the instru- or is supplied by an internal source, such as a
ment forward. positioning or balance control, causes the spot to
move from the center of the screen. As the in-
If the 130BR has been rack-mounted with brackets strument ages it is to be expected that a drift will
as described in Figure 1-3, remove the screws occur which must be compensated by internal ad-
which pass through the front panel, and withdraw justments. However, should there be a component
the chassis. If the instrument is out of the rack, failure in either amplifier the spot will be thrown
turn it on its face (handles will protect the con- off the screen and usually out of range of adjust-
trols), remove the two screws at the rear, and ment of the balance and positioning controls. To
lift off the dust cover. isolate the trouble, begin by shorting together the
grids of the amplifier closest to the output. If the
trace (spot) returns to the screen, the fault is
4-4 ISOLATING TROUBLES TO MAJOR ahead of this stage. Proceed towards the front of
S ECTlO NS the amplifier. If shorting the grids of one stage
? does not return the spot to the screen, the fault is
Determining which major section contains a mal- in this stage, or if there is a balancing control in
function is usually not a difficult process, if the this stage, it may be out of adjustment.
following general rules are remembered.
7) To check the Sweep Generator quickly, set the
1) A failure affecting all major sections can SWEEP TIME/CM switch to 5 or 10 MILLI-
usually be traced to the power supply. SECONDS/CM, turn the SWEEP MODE control to
FREE RUN, and observe 1201, I202 and 1203.
2) A failure occurring in the last two stages of the These are the three neon lamps near V206 (6AW8)
Horizontal Amplifier also will affect internally on the Sweep Generator etched circuit board. If
generated sweeps, while a failure in the first two these lamps flicker regularly, the Sweep Gener-
stages affects only the Horizontal Amplifier. ator is sweeping. Turning the SWEEP MODE into
the TRIGGER region should stop the generation
3) A sweep Generator failure affects internally of sweeps and, hence, the flickering of the neon
generated sweeps only, and does not affect the lamps.
Horizontal Amplifier.
4) If following the Simple Check Procedure does
not produce a trace or spot on the screen, mea- 4-5 CONNECTING FOR 230 VOLT OPERATION
sure the voltages on the deflection plates of the Unless otherwise requested by the customer, @
Cathode-Ray Tube (deflection plate terminal board instruments are shipped with their power trans-
is a convenient place to measure). If, with both former primaries connected in parallel for oper-
VERT. and HORIZ. SENSITIVITY switches set to ation on 115 volt (nominal) power lines.
50 MILLIVOLTS/CM, these voltages can be set
to approximately 480 vdc using the position con- To convert to 230 volt supply, remove the instru-
trols, look for trouble in the high voltage section ment from its cabinet or dust cover by removing
of the power supplies. If one set of deflection the two screws at the rear of the chassis, and
.j 00013-2 |
ACEC
