Measurement Bandwidth And Self Characterization; Initial Control Settings; Procedure; Volts Cal (R920) - Tektronix 2246 1Y Service Manual

Adjustment Procedure—2246 1Y and 2246 Mod A Service
MEASUREMENT BANDWIDTH AND SELF
Equipment Required (See Table 4-1):
Digital Multimeter (DMM)
Leveled Sine— Wave Generator
at the back of this manual for locations of test points and adjustments.

INITIAL CONTROL SETTINGS

Set:
Vertical MODE
INPUT COUPLING
VOLTS/DIV
Vertical POSITION
Controls
SCOPE BW
Horizontal MODE
A/B SELECT
SEC/DIV
Trigger LEVEL
HOLDOFF
SLOPE
Trigger MODE
Trigger SOURCE
Trigger COUPLING
MEASUREMENTS
MENU Displays
A INTEN
READOUT
FOCUS
SCALE ILLUM

PROCEDURE

1. Volts Cal (R920)

a. Connect digital multimeter (DMM) LO lead to
chassis ground and the high lead to R921 pin 6.
5-14
CHARACTERIZATION
See the ADJUSTMENT LOCATIONS section
b.

2. B Trigger Bandwidth (R455)

CH 1 and CH 2
DC a.
0.1 V
12 o ' clock
Off
A
A
b.
0.1 ms
12 o 'clock
c.
min (CCW)
- T
AUTO LEVEL
d.
VERT
DC
OFF
OFF
10 o ' clock
e.
12 o'clock
for well defined
display
fully CCW
f.

3. Self Characterization

a.
50 f l Coaxial Cable
ADJUST-VOLTS CAL (R920) so the DMM reads
0.250 V.
Set:
Vertical MODE
CH 2 VOLTS/DIV
SEC/DIV
Preset potentiometer R455 to midrange.
Run the SELF CAL routine.
VOLTMETER button and select SELF CAL.
Connect leveled sine-wave generator output to
the CH 2 input connector via a 50 Cl BNC pre­
cision coaxial cable and a 50 f l BNC termination.
Set generator for a 5-division display at 50 kHz.
Set CH1/CH2 VOLTMETER for PK-PK voltage
measurement. Set output of Leveled Sine-Wave
Generator for a peak-to-peak readout display of
100 mV ±0.5 mV. Adjust generator to 115 MHz.
ADJUST-B TRIG BANDWIDTH (R455) for a peak-
to-peak readout of 75 mV ±0.5 mV.
Run the SELF CAL MEASUREMENTS routine.
Press both top and bottom menu-item select
buttons. Select INTERNAL SETTINGS MENU, then
CH 2 (CH 1 off)
20 mV
50 (is
Press CH1/CH2