HP 120 schematic

THIS IS A REPRINT, INCLUDING CHANGES 1 AND 2

*TB 9-6625-082-50

DEPARTMENT OF THE ARMY TECHNICAL BULLETIN

CALIBRATION PROCEDURE FOR

OSCILLOSCOPE, HEWLETT-PACKARD

MODELS 120A, 120AR, 120B. AND 120BR

Headquarters, Department of the Army, Washington, DC

14 January 1974

♦♦REPORTING OF ERRORS♦♦

You can help improve this publication by calling attention to errors and by recommending improvements and stating your reasons for the recommendations. Your letter or DA Form 2028, Recommended Changes to Publications, should be mailed directly to Commander, U.S. Army Aviation and Missile Command, ATTN: AMSAM-TMD-EP, Redstone Arsenal, AL 35898-5000. FAX to DSN 7882313 (commercial 256-842-2313). A reply will be furnished directly to you.

SECTION I. IDENTIFICATION AND DESCRIPTION

Test instrument identification .............................. 1 2

Calibration data card, DA Form 2416 .................. 2 2

Calibration description......................................... 3 3

II. EQUIPMENT REQUIREMENTS

Equipment required.............................................. 4 4

Accessories required ............................................. 5 5

III. PRELIMINARY OPERATIONS

Preliminary instructions....................................... 6 5

Equipment Setup.................................................. 7 6

IV. CALIBRATION PROCESS FOR MODELS

120A AND 120 AR

Intensity limit.................................................... 8 6

Vertical and horizontal amplifier dc balance..... 9 7

Triggering range and level................................. 10 9

Vertical and horizontal sensitivity and range ... 11 12

Calibrator........................................................... 12 13

Vertical amplifier frequency response and

attenuator compensation ................................... 13 13

Horizontal amplifier frequency response and

attenuator compensation ................................... 14 14

Amplifier phase shift.......................................... 15 16

Paragraph Page

__________

This bulletin supersedes TB 9-6625-082-50, 17 September 1970.

TB 9-6625-082-50

V. CALIBRATION PROCESS FOR MODELS

Paragraph Page

Sweep timing...................................................... 16 16

Sweep magnifier................................................. 17 17

Power supply ...................................................... 18 18

Final procedure.................................................. 19 18

120B AND 120BR

Equipment setup................................................ 20 19

Intensity limit.................................................... 21 19

Vertical amplifier dc balance............................. 22 20

Triggering range and level................................. 23 21

Vertical and horizontal sensitivity and range ... 24 23

Calibrator........................................................... 25 24

Vertical amplifier frequency response and

attenuator compensation ................................... 26 24

Horizontal amplifier frequency response and

attenuator compensation ................................... 27 27

Amplifier phase shift.......................................... 28 28

Sweep timing...................................................... 29 28

Sweep magnifier................................................. 30 29

Power supply ...................................................... 31 30

Final procedure.................................................. 32 30

SECTION I

IDENTIFICATION AND DESCRIPTION

1. Test Instrument Identification. This bulletin provides instructions for the

calibration of Oscilloscope, Hewlett-Packard Models 120A, 120AR, 120B, and 120BR. The manufacturer’s instruction manuals were used as the prime data source in compiling these instructions. The oscilloscope will be referred to as the "TI" (test instrument) throughout this bulletin.

a. Model Variations. Variations among models are described in text. b. Time and Technique. The time required for this calibration is approximately 4

hours using the dc and low frequency technique.

2. Calibration Data Card, DA Form 2416

a. Forms, records, and reports required for calibration personnel at all levels are

prescribed by TM 38-750. DA Form 2416 must be annotated in accordance with TM 38-750 for each calibration performed.

b. Adjustments to be reported on DA Form 2416 are designated (R) at the end of the sentence in which they appear. When adjustments are in tables, the (R) will follow the designated adjustment. Report only those adjustments made and designated with (R).

TB 9-6625-082-50

3. Calibration Description. TI parameters and performance specifications which

pertain to this calibration are listed in table 1.

Table 1. Calibration Description

Test instrument parameters Performance specifications Power input requirements Vertical and horizontal amplifier bandwidth

(models 120 and 120AR): Dc coupled Ac coupled

Vertical amplifier bandwidth (models 120B and

120BR): Dc coupled Ac coupled

Horizontal amplifier bandwidth (models 120B and

120BR): Dc coupled Ac coupled

Horizontal sensitivity:

Range Vernier

Accuracy

Vertical sensitivity:

Range Vernier Accuracy (models 120A and 120AR)

Accuracy (models 120B and 120BR)

Internal calibrator Calibrator signal automatically connected to

Common-mode rejection

Phase shift Vertical and horizontal amplifiers have same

See footnote at end of table.

115 or 230 vac ±10%, 50 to 1000 Hz, 130 w

Dc to 200 kHz 2 Hz to 200 kHz

Dc to 450 kHz 2 Hz to 450 kHz

Dc to 300 kHz 2 Hz to 300 kHz

0.1 to 100 v/cm in 3 calibrated steps; .1, 1, and 10 v/cm

Continuously variable between steps and extends

10 v/cm step to at least 100 v/cm

±5%

10 mv/cm to 100 v/cm in 4 calibrated steps; 10 mv,

100 mv, 1 v, and 10 v/cm

Continuously variable between steps and extends

10 v/cm step to at least 100 v/cm

±5% ±3%

vertical amplifier; accuracy ±2%

At least 40 db. Common mode signal must not

exceed ±3 v peak

phase characteristics within ±2° to 100 kHz when verniers are in CAL

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Table 1. Cable Description - Continued.

Test Instrument Parameters Performance Specifications

Sweep:

Sweep range

Vernier

Accuracy Sweep expand

Automatic triggering (models 120A and 120AR):

Internal

External Trigger point

Automatic triggering (models 120B and 120BR):

Internal

External Trigger point

Selectable trigger level:

Models 120A and 120AR

Models 120B and 120BR

This specification is for information only and is not necessarily verified in this bulletin.

1 µsec to 0.5 sec/cm in 15 calibrated steps 1, 2, 5,

10, etc., sequence, 5 µsec/cm to 200 ms/cm

Continuously variable between ranges and

extends 200 ms/cm step to at least 0.5 sec/cm

±5% X5 sweep expansion may be used on all ranges

and extends fastest sweep to 1 µsec/cm, accuracy ±10%

From signals 50 Hz to 250 kHz causing 0.5 cm or

more vertical deflection; and from line voltage

At least 2.5 v p-p Zero crossing, negative slope of external sync

signals; zero crossing, positive or negative slope of vertical deflection signal

From signals 50 Hz to 450 kHz causing 0.5 cm or

more vertical deflection; and from line voltage

At least 1.5 v p-p Zero crossing, negative slope of external sync

signals; zero crossing, positive or negative slope of vertical signal

Screwdriver control overrides automatic

triggering and permits trigger point to be set between -10 to +10 v

Front-panel control overrides automatic triggering

and permits trigger point to be set between -7 to +7 v

SECTION II

EQUIPMENT REQUIREMENTS

4. Equipment Required. Table 2 identifies the specific equipment used in this

calibration procedure. This equipment is issued with secondary transfer calibration standards set 4931-621-7877 and is to be used in performing this procedure. Alternate items may be used by the calibrating activity when the equipment listed in table 2 is not available. The items selected must be verified to perform satisfactorily prior to use and must bear evidence of current calibration. The equipment must meet or exceed the minimum use specifications listed in table 2. The accuracies listed in table 2 provide a fourto-one accuracy ratio between the standard and TI. Where the four-to-one ratio cannot be met, the actual accuracy of the equipment selected is shown in parenthesis.

TB 9-6625-082-50

5. Accessories Required. The accessories listed in table 3 are issued with secondary

transfer calibration standards set 4931-621-7877 and are to be used in this calibration procedure. When necessary, these items may be substituted by equivalent items unless specifically prohibited.

Table 2. Minimum Specifications of Equipment Required

Minimum use

Item Common name

A1 AC/DC VOLTMETER Range:-146 to -154 V dc;

Accuracy: ±..75%

A2 AUTOTRANSFORMER Range:105 to 125 V ac

Accuracy: ±1%

A3 DC VOLTMETER Range:-1235 to -2363 V

Accuracy: ±1.66%

A4 SIGNAL GENERATOR Frequency: 100 kHz

Voltage: 0.03 to 20 V rms

A5 SQUARE-WAVE

GENERATOR

A6 VOLTAGE

CALIBRATOR

A7 TEST OSCILLATOR Frequency: 10 Hz to 500 kHz

A8 TIME-MARK

GENERATOR

Frequency: 5 to 30 kHz Voltage: 0.8 to 50 V p-p Range:34.5825 mv rms to 37.2

Accuracy: ±..75% Voltage: 0.03 to 2.9 v rms

Accuracy: ±.75% Range:1 µsec to 50 ms Accuracy: ±..75%

specifications

+33.58 to +37.12 V ac

v rms

Manufacturer and model

(part number)

Dana, Model 5703-S-2127

(7912606)

General Radio, Model

W10MT3AS3 (7910809)

Electrical Instruments Service,

Model ESV (MIS-10276)

Hewlett-Packard, Model 202CR

(8616395-2)

Tektronix, Type 106 (MIS-

10284)

Hewlett-Packard, Model 745A

(MIS-10342)

Preston, Model 134A (MIS-

10224)

Tektronix, Type 184MOD146B

(7912042-2)

Table 3. Accessories Required

Item Common Name Description and Part Number

B1 ADAPTER B2 ADAPTER BNC jack to double banana plug (7907592) B3 ADAPTER BNC T type, 2 jacks, 1 plug (MS35173-274) B4 CABLE 30-in., RG-58/U; BNC plug terminations (7907467) B5 CABLE B6 CABLE

B7 LEAD 24-in., No. 18 AWG; single banana plug terminations (7907498) B8 TERMINATION 50-ohm feed-through; BNC jack to BNC plug Hewlett-Packard,

Two required.

1 1

Single banana jack to alligator clip (black) (7907560)

30-in., RG-58/U; double banana plug terminations (7907470) 36-in., RG-58/U; BNC plug and double banana plug terminations

(7907471)

Model 11048B (11048B)

SECTION III

PRELIMINARY OPERATIONS

6. Preliminary Instructions

a. The instructions outlined in this section are preparatory to the calibration process.

Personnel should become familiar with the entire bulletin before beginning the calibration.

TB 9-6625-082-50

b. Items of equipment used in this procedure are referenced within the text by common

name and item identification number as listed in tables 2 and 3. For the identification of equipment referenced by item numbers prefixed with A, see table 2, and for prefix B, see table 3.

WARNING

HIGH VOLTAGE is used during the performance of this calibration. DEATH ON CONTACT may result if personnel fail to observe safety precautions.

7. Equipment Setup

a. Remove protective cover from TI. b. Connect TI to autotransformer (A2). c. Connect autotransformer to 115-volt ac source and adjust for 115 volts ac.

CAUTION

To prevent damage to crt, turn INTENSITY control fully counterclockwise during warm-up.

d. Energize equipment and allow sufficient time for equipment to warm up and

stabilize.

SECTION IV

CALIBRATION PROCESS FOR MODELS 120A AND 120AR

NOTE

Unless otherwise specified, verify the results of each test and take corrective action whenever the test requirement is not met before continuing with the procedure.

NOTE

When indications specified in paragraphs 8 through 17 are not within tolerance, perform the power supply check prior to making adjustments. After adjustments are made, repeat paragraphs 8 through 17. Do not perform power supply check if all other parameters are within tolerance.

8. Intensity Limit a. Performance Check

(1) Position TI controls as listed in (a) through (i) below:

(a) TRIGGER LEVEL control to AUTO. (b) INTENSITY control fully counterclockwise. (c) Vertical AC-DC switch to AC. (d) VERT. SENSITIVITY VERNIER control to CAL. (e) VERT. SENSITIVITY switch to 1 VOLTS/CM. (f) SWEEP EXPAND switch to X1. (g) SWEEP TIME-HOR. SENS. switch to 1 MILLISECONDS/CM. (h) SYNC switch to INT + (positive). (i) HORIZ. POS. and VERT. POS. controls to midrange.

(2) Adjust INTENSITY and FOCUS controls for normal display. If normal display

cannot be obtained, perform b below.

b. Adjustments

(1) Position TI controls as listed in (a) through (c) below:

TB 9-6625-082-50

(a) SWEEP TIME-HOR. SENS. switch to 10 VOLTS/CM. (b) FOCUS control for best focus.

(c) INTENSITY control index marker to 9 o'clock position. (2) Adjust R316 (fig. 1) for a small round spot. (3) Adjust R322 (fig. 1) until spot just disappears.

9. Vertical and Horizontal Amplifier Dc Balance

a. Performance Check

(1) Position TI controls as listed in (a) through (e) below:

(a) VERT SENSITIVITY switch to 10 VOLTS/CM.

(b) VERT SENSITIVITY VERNIER control fully counterclockwise.

(d) Vertical AC-DC switch to DC.

(e) SWEEP TIME-HOR SENS. switch to 10 VOLTS/CM.

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(2) Vary VERT. SENSITIVITY VERNIER control. If spot does not remain in center

of graticule, perform b(1) through (3) below.

(3) Turn VERT SENSITIVITY VERNIER control to CAL. VERT SENSITIVITY to

OFF, and SWEEP TIME HOR. SENS. switch to 10 V/CM.

(4) Repeat (1) and (2) above, using horizontal controls. If spot does not remain in

center of graticule, perform b(4) through (8) below.

Figure 1. Oscilloscope - top view.

b. Adjustments

(1) Turn VERT SENSITIVITY VERNIER control to midrange. (2) Adjust VERT. DC BAL. control (front panel) to center spot on graticule. (3) Vary VERT. SENSITIVITY VERNIER control and adjust VERT. DC BAL.

control until no spot shift is observed.

(4) Turn SWEEP TIME-HOR. SENS. VERNIER control fully counterclockwise. (5) Adjust R110 (fig. 1) to center spot on graticule. (6) Turn SWEEP TIME-HOR. SENS. VERNIER control to CAL. (7) Turn HORIZ. POS. control to center spot on graticule. (8) Repeat (4) through (7) above until no shift is observed when varying SWEEP

TIME HOR. SENS. VERNIER control.

10. Triggering Range and Level

TB 9-6625-082-50

a. Performance Check

(1) Position TI controls as listed in (a) through (c) below:

(a) VERT SENSITIVITY switch to 1 VOLTS/CM.

(b) SWEEP TIME-HOR. SENS. switch to 5 MICROSECONDS/CM.

(c) SYNC switch to EXT. (2) Observe that baseline is displayed on TI crt. (3) Connect test oscillator (A7) to TI horizontal input connector, using cable and

termination (B6 and B8).

(4) Connect TI horizontal input connector to TI vertical input connector, using cable

(B5).

(5) Adjust test oscillator frequency to 250 kHz and amplitude for stable display on

TI.

(6) Slowly reduce test oscillator amplitude until TI display becomes unstable. If

test oscillator amplitude is not .70 volt rms or less, perform b(1) and (2) below.

(7) Turn SWEEP TIME-HOR. SENS. switch to 10 MILLISECONDS/CM.

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(8) Adjust test oscillator frequency to 50 Hz and amplitude for display on TI. (9) Repeat (6) above.

NOTE

Some adjustment of TI TRIGGER LEVEL control may be necessary at high frequencies.

(10) Turn SYNC switch to INT + (positive) and SWEEP TIME-HOR. SENS. switch to

50 MICROSECONDS/CM.

(11) Adjust test oscillator to 10 kHz and .8 centimeters of display on TI crt. If sweep does not trigger on positive-going portion of display waveform, perform b(3) through (11) below.

(12) Turn SYNC switch to INT-(negative). Observe that sweep triggers on negative going part of waveform.

b. Adjustments

(1) Adjust test oscillator amplitude for stable display on TI. (2) Adjust R247 (fig. 2) while reducing test oscillator amplitude until triggering

becomes stable at minimum test oscillator amplitude (less than .70 volt rms).

(3) Turn TI VERT. SENSITIVITY VERNIER control to CAL. (4) Connect ac/dc voltmeter (A1) between pin 8 of V203 (fig. 2) and chassis ground. (5) If no trace is present on TI, perform adjustments (a) and (b) below:

(a) Adjust R228 (fig. 1) counterclockwise until trace appears.

(b) Turn R228 clockwise until trace just disappears. (6) If trace is present, adjust R228 clockwise until trace just disappears. (7) Record ac/dc voltmeter indication. (8) Connect lead (B7) with two adapters (B1), between pin 1 of V201 (fig. 2) and

chassis ground.

(9) Slowly turn R228 counterclockwise until trace appears and then clockwise until

trace just disappears. Record ac/dc voltmeter indication.

above.

(10) Adjust R228 for indication of 2 volts more positive than value recorded in (9)

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