Adjustment Procedure-2445A/2455A Service
DAC REF,
CH
1 AND CH 2 INPUT CAPACITANCE, AND VERTICAL
READOUT JITTER ADJUSTMENTS
Equipment Required
Calibration Generator (Item 3)
50 n
BNC
Cable (Item 10)
50 n Termination (Item 12)
Digital Multimeter (DMM) (Item
19)
Alignment Tool (Item 20)
Normalizer (Item 22)
See
ADJUSTMENT LOCATIONS 3 and ADJUSTMENT LOCATIONS 4
at
the back
of
this manual for test point and adjustment locations.
INITIAL CONTROL SETTINGS
Control settings not listed do not affect the procedure.
VERTICAL
CH
1
and
CH
2
VOLTS/DIV
CH
1
and
CH
2
VAR
CH
1
and
CH
2
Input Coupling
CH
1
CH
2,
CH
3,
CH
4
ADD, INVERT,
and
BW
LIMIT
ALT/CHOP
POSITION
HORIZONTAL
A SEC/DIV
SEC/DIV
VAR
POSITION
TRIGGER
MODE
SOURCE
COUPLING
SLOPE
LEVEL
HOLDOFF
100 mV
In
detent
1 Mn
DC
On
Off
Off
ALT
Midrange
100
µs
(knob
in)
In
detent
Midrange
AUTO LVL
VERT
DC
+ (plus)
Midrange
In
detent
Delta
at
TRACKING/INDEP
Display
On
(at readout)
INDEP
INTENSITY Left
of
center
READOUT INTENSITY
As
required for a
visible display
SCALE ILLUM Fully CCW
FOCUS Best focused display
1. Adjust DAC Ref (R2010).
NOTE
The
objective
of
this step is to make the total range
of
the
DAC output voltage
(sum
of
the CCW and
CW readings) equal to 2.5
V.
a.
Connect the digital multimeter (DMM) negative lead
to
the chassis ground. Connect the positive lead to pin 13
of J119
(on
the Main Board).
b.
Set the DMM
to
measure approximately 1.5 Vdc.
c.
Rotate the a control CCW until the DMM reading
remains at a constant value (approximately
-1.250
V).
Note the reading.
5-7
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