Tektronix 485 Bedienungsanleitung

Andere Handbücher für 485

1

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1

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TEKTRONIX®

485/R485

OSCILLOSCOPE

SERVICE

INSTRUCTION M ANU AL

Tektronix, Inc.

P. . Box 5

Beaverton, Oregon 97 5 Serial Number

070-1193-00 473

485/R485 Service

TABLE OF CONTENTS

SECTION 1 S ECIFICATION age

Introduction 1-1

Vertical Deflection System 1-1

Probe Performance 1-3

A and B Triggering 1-3

Horizontal Deflection 1-4

Calibrated Sweep Delay 1-4

X-Y 1-5

CRT 1-5

Calibrator 1-6

Other Characteristics 1-6

Environmental Characteristics 1-6

SECTION 2 O ERATING INSTRUCTIONS

General 2-1

Preliminary Information 2-1

Controls and Connections 2-1

Front Panel 2-1

Rear Panel 2-4

Bottom Side 2-4

SECTION 3 CIRCUIT DESCRI TION

Introduction 3-1

5 n Attenuator 3-1

1 Megohm Buffer Amplifier 3-1

5 n Overload Protection 3-1

Vertical Preamplifier 3-1

Signal Channel Switch 3-2

Internal Trigger Amplifier 3-2

Main Vertical Amplifier 3-2

Scale Factor Readout 3-3

Vertical Mode Control 3-3

Z Axis 3-3

A Trigger Amplifier 3-3

A EXT Trigger Identify 3-3

A Trigger Generator 3-4

B Trigger Generator 3-4

A and B Sweeps 3-4

Horizontal Amplifier 3-5

Horizontal Control 3-5

Power Inverter/Regulator 3-6

Line Filter 3-6

Line Input Circuit 3-6

Start Network 3-7

I nverter 3-8

Inverter/Regulator 3-8

Inverter Current Limiting Circuit 3-8

Overvoltage Stop Circuit 3-8

Line Stop Circuit and Surge Limiting 3-8

Procedure for Converting the 485 to

DC Operation 3-9

Low Voltage Supplies 3-9

Power Supply Protection Circuit 3-1

Stop Monostable 3-1

Balance Node 3-1

Overcurrent Protection 3-12

Low Line Voltage Protection 3-12

Sampling Period Timer and Over-

Voltage Protection 3-12

CRT Circuit 3-12

Filament Voltage 3-12

High Voltage Supplies 3-12

Anode Supply 3-12

Cathode Supply 3-12

Cathode Regulator 3-12

Grid DC Restorer 3-13

SECTION 3 CIRCUIT DESCRI TION (cont) age

Focus DC Restorer 3-13

Beam Current Limit 3-14

Power Supply Shutdown Caused by

Excessive Beam Current 3-14

CRT Control Circuits 3-14

Auto Focus Circuit 3-14

Calibrator 3-15

SECTION 4 MAINTENANCE

Introduction 4-1

Cover Removal and Reinstallation 4-1

Cleaning 4-1

Lubrication 4-2

Visual Inspection 4-3

Semiconductor Checks 4-3

Recalibration 4-3

Troubleshooting 4-3

Introduction 4-3

Troubleshooting Aids 4-3

Circuit Boards 4-3

Troubleshooting Equipment 4-5

Troubleshooting Techniques 4-6

Special Troubleshooting Information 4-7

Corrective Maintenance 4-11

Obtaining Replacement Parts 4-11

Soldering Techniques 4-11

Component Replacement 4-12

Circuit Board Replacement 4-12

Timing Board Removal 4-12

Transformer Board Removal 4-13

Inverter Board Removal 4-14

Semiconductor Replacement 4-14

Circuit Board Pins 4-14

End Lead Pin Connectors 4-15

Cathode Ray Tube Replacement 4-15

Repackaging for Shipment 4-15

Interboard Comb Connection Locations 4-16

SECTION 5 CALIBRATION

Introduction 5-1

TEKTRONIX Field Service 5-1

Using This Procedure 5-1

Test Equipment Required 5-1

Special Calibration Fixtures 5-1

Calibration Equipment Alternatives 5-4

Performance Check 5-4

Calibration Procedure 5-8

SECTION 6 RACKMOUNTING

Introduction 6-1

Rack Dimensions 6-1

Slide Out Tracks 6-1

Mounting Procedure 6-1

Alternate Rear Mounting Methods 6-2

Removing or Installing the Instrument 6-2

Slide Out Track Lubrication 6-2

SECTION 7 ELECTRICAL ARTS LIST

SECTION 8 DIAGRAMS AND CIRCUIT BOARD

ILLUSTRATIONS

SECTION 9 MECHANICAL ARTS LIST

CHANGE INFORMATION

REV. B, MAR. 1976 I

485/R485 :rviice Th* « 5 ' “0 Oscil'oscope.

SPECIFICATION

Section 1—485/R485 Service

Introduction

The 485/R485 is a general-purpose, environmentalized,

high-performance, portable, wide-band oscilloscope which

has a dual-channel vertical amplifier with selectable input

impedance (DC to 350 MHz bandwidth with 50 £2 input

impedance; DC to 250 MHz bandwidth with 1 M£2 input

impedance). The 485 has a 1 ns sweep rate, stable triggering

to bandwidth limits and calibrated X-Y capabilities.

Delayed sweep has calibrated delay time, can be triggered

after delay and can be displayed with the intensified main

sweep in an alternate sweep switching display. Additional

features are X I0, X I00 probe scale factor readout, 8 div

X10 div graticule area, small spot size and high writing rate.

A 20 MHz bandwidth limiter, 1 MHz and 1 kHz fast-rise

calibrator and autofocus are also included. The 50 £2 input

is automatically disconnected from excessive voltages. An

external trigger view feature is also provided. The 485-1 and

485-2 have no external trigger view. The 485-2 has only 50

£2 vertical input impedance.

ELECTRICAL CHARACTERISTICS

Input Coupling Selection

AC; DC; GND (provides zero reference, precharges

coupling capacitor, disconnects 50 £2 load in 50 £2

mode).

Lower —3 dB Point (AC coupling from 5 £2

source)

50 £2 input, 1 kHz or less.

1 M£2 input IX, 10 Hz or less.

Deflection Factor

5 mV/div to 5 V/div in 10 calibrated steps (1-2-5

sequence), accurate within 2%. Uncalibrated, continu

ously variable between steps to at least 12.5 V/div.

Lights at edge of knob skirts indicate correct deflection

factor for IX, 10X and 100X probes.

Gain can be recalibrated at front panel. 1 M£2 BAL is

available at bottom panel to eliminate step attenuator

shift above 10 mV/div, in the 1 M£2 mode.

VERTICAL DEFLECTION SYSTEM

(2 identical channels)

Display Modes

Channel 1; Alternate; Chopped (approximately 1 MHz

rate); Added; X-Y (CH 1 -Y and CH 2 -X ); Channel 2

(+Up or Inverted).

Selectable Input Impedance

50 £2 within 0.5%. VSWR <1.25:1 on 5 mV/div and

10 mV/div, 1.15:1 from 20 mV to 5 V/div to 350 MHz.

1 M£2 within 1% paralleled by approximately 20 pF.

Bandwidth1 and Risetime2 (VARIABLE gain

CALIBRATED3) From 5 £2 Terminated Source

—15°C to +35°C

From 50 £2 terminated source —15°C to +35°C.

50 £2 DC to at least 350 MHz, 1 ns

1 M£2 DC to at least 250 MHz, 1.4 ns

Bandwidth (BW) measured at —3 dB down.

2Risetime calculated from .35/BW. From +35°C to +55°C, BW is

3 MHz for 5 ft and 2 MHz for 1 MU.

3See Fig. 1-1 for effect of VARIABLE gain control.

Internal Trigger Source

Normal (displayed signal), Channel 1 or Channel 2

signal.

5

4

3

200

BW,

MHz

100

5

Fig. 1-1. Typical Bandwidth, 5 ft vs. Variable Gain Setting (varies

considerably depending on instrument SNI

/

/

TYP

VA

ICAL BAh

V

RIABLE C

DWIDTH.

IS.

AIN SET!

5 ft

ING

5 % 1 %

Percent of CAL Gain

REV C. MAR 1979 1-1

Specification—485/R485 Service

Fig. 1-2. Typical 5 SI Protection Disconnect Characteristic.

5 S2 Protection

Internal detection circuitry automatically disconnects

excessive signals of up to 50 V. The disconnected

condition is indicated, and has manual reset.

Maximum Input Voltage

50 Q. Disconnect occurs for voltages that exceed approx

imately 5 V RMS continuous or 0.1 watt-second for

instantaneous voltages of 5 V to 50 V.

Repeated application of voltages in excess of 50 volts

and greater than 0.1 watt-second will cause deterioration

of K1S1 relay contacts, due to arcing. Signals in excess

of 150 volts will damage the instrument.

1 Mft-DC coupled 250 V (DC + peak AC), 500 V - to

1 kHz. AC coupled 500 V (DC + peak AC), 500 V - to

1 kHz.

Common Mode Rejection

Added Mode with Channel 2 inverted. At least 10:1 at

50 MHz for 8-division signal after adjusting CH 2 gain

for best CMR at 50 kHz and 20 mV/div.

Bandwidth Limiter

Limits to approximately 20 MHz the Vertical Amplifier

and Internal Trigger signals.

Channel Isolation

At least 30:1 at 350 MHz.

A Ext Trigger Display (R485 and 485 only)

Momentary pushbutton in VERT MODE area enables

display of EXT A Trigger when A source is in EXT

position. Deflection factor is approximately 50 mV/div.

Risetime is approximately 1.5 ns. Delay match to CH 1

or CH 2 input is within 0.5 ns at 50% amplitude.

Triggering level is within 0.5 div of center-screen.

Probe Power

Two 4-pin connectors at the rear of the instrument

provide power suitable for optional active probes such as

the 6201.

1-2 ®!

Specification—485/R485 Service

ROBE ERFORMANCE

( robes are Optional Accessories)

Temperature Range

Lower Bandwidth for this

Input —3 dB point with 485 Bandwidth

Type Atten. Impedance (maximum) (minimum) Specification

For Use With 50 $2 Input

010-6056-03 - 6 ft .

6056 10X 500 S2 1 pF 200 Hz 350 MHz

010-6056-05-9 ft.

010-6057-03 - 6 ft . -1 5°C to +35°C

6057 100X 5 kS2 1 pF 20 Hz 350 MHz

010-6057-05-9 ft.

.IX 100 kJ2 3 pF 10 Hz

6201 0°C to +35° C

010-6201-01 - 6 ft. lug- 10X 1 MS2 <1.5 pF 1 Hz 330 MHz

(FET robe) On 100X 1 MS2 <1.5 pF 10 Hz

For Use With 1 MS2 Input

010-6053-11 - 3 1/2 ft. 1 M£2 9.5 pF 250 MHz

6053A 010-6053-13 - 6 ft. 10X 1 M£2 12 pF 1 Hz 250 MHz —15°C to +35° C

010-6053-15-9 ft. 1 ML2 13.5 pF 200 MHz

A and B TRIGGERING

A Trigger Mode

NORMAL.

Sweep runs only when triggered.

AUTOMATIC.

Sweep free-runs in the absence of a triggering signal

and for signals below 20 Hz.

SINGLE SWEE .

Sweep runs one time on the first triggering event after

pressing the reset selector.

Time Base A and B Trigger Sensitivity

Trigger Mode To 50 MHz At 350 MHz

DC Int 0.3 div 1.5 div

DC Ext 20 mV 100 mV

AC Signals below 16 Hz are attenuated.

LF Reject Signals below 16 kHz are attenuated.

HF Reject Signals below 16 Hz and above 50 kHz

are attenuated.

B Trigger Mode

B RUNS AFTER DELAY TIME.

Starts automatically at the end of the delay time.

B TRIGGERABLE AFTER DELAY TIME.

Runs when triggered. The B (delayed) sweep runs

once, in each of these modes, following the A sweep

delay time.

Level and Slope

Internal, permits selection of triggering point at any level

on the positive and negative slope of the displayed

waveform. External, level is adjustable through at least

±0.5 V for either polarity (±5 V for EXT -MO).

A Source

Internal, Line, External, External MO.

REV. B, AUG. 1977 1-3

Specification—485/R485 Service

B Source

B runs after Delay Time, Internal, External, External

•MO.

External Inputs

1 M£2 paralleled by approximately 20 pF. Maximum

input voltage 500 V (DC + peak AC), 500 V - to

1 kHz.

Jitter

Less than 0.1 ns at 350 MHz and 1 ns/div.

HORIZONTAL DEFLECTION

Time Base A and B

1 ns/div to 0.5 s/div in 27 calibrated steps (1-2-5

sequence). Uncalibrated, A is continuously variable

between steps and to at least 1.25 s/div.

Time Base A and B Sweep Accuracy (Center 8

screen divisions)

Sweep Rate +15°C to +35°C —15°C to +55°C

1 ns/div to 20 ns/div ±3% ±5%

50 ns/div to 0.1 s/div ±2% ±4%

0.2 s/div to 0.5 s/div ±3% ±5%

Display Modes

A, A INTEWsified during B delayed, ALTernate display

of A INTEN and B (delayed sweep). Only A sweep is

displayed for A sweep rates of 1, 2 and 5 ns/div.

Minimum Sweep Holdoff (A Trigger Holdoff in

Norm detent)

A Time Setting

1 ns/div to 0.1 ps/div Less than 0.4 ps.

0.2 ps/div Less than 1.0 ps.

0.5 ps/div to 0.5 s/div Less than 2 times the

A TIME/DIV setting.

A Trigger Holdoff

Adjustable control permits a stable presentation of

repetitive complex waveforms. The control covers at

least the time of one full sweep for sweeps faster than

0.2 s/div.

B Ends A

The A sweep is reset at the end of the B sweep to allow

the fastest possible sweep repetition rate for increased

trace intensity in the delayed sweep mode.

CALIBRATED SWEEP DELAY

Delay Time Range

0 to 9.9 times the Delay Time/Div settings of 10 ns/div

to 0.5 s/div.

Differential Delay Time Accuracy (+15°C to

+35° C)

Exclude the first (above 0.0) 1.0 turn or the first 40 ns

of the DELAY dial.

DELAY TIME Setting

10 ns/div and 20 ns/div ± (1% of measurement

+0.2% of full scale3)

50 ns/div to 1 ms/div ± (0.5% of measurement

+0.1% of full scale)

2 ms/div to 0.5 s/div ± (1% of measurement

+0.1% of full scale)

3Full scale is 1 X the Delay Time/Div Setting.

®!

1-4

Specification—485/R485 Service

DIFFERENCE Between Two Dial

Readings, Major D.T. . Divisions

Fig. 1-3. Specified Differential Delay Accuracy vs. Size of Measure

ment.

Jitter

Less than 0.005% (one part in 20,000) of full scale plus

0.2 ns. (Wrap-around cover must be in place.)

X-Y

Full Sensitivity

(CH 1 Vert, CH 2 Horizontal.) 5 mV/div to 5 V/div in

10 calibrated steps (1-2-5 sequence) accurate within 2%.

Gain can be recalibrated at front panel.

Y Performance

Identical to CH 1. See Vertical Deflection.

X-Axis Bandwidth

DC to 4 MHz (with 10 div reference signal).

X-Y Phase Match (Full BW and BW Limit)

Within 3° to 4 MHz.

X-Gain Match to CH 2

+15°C to +35°C: 1%

—15°C to +55°C: 3%

CRT

TEKTRONIX CRT

4-inch rectangular tube; 8X 10 divisions (0.8 cm/div)

display area. 31 phosphor normally supplied; 11

optional without extra charge. 21 kV accelerating

potential.

Photographic Writing Speed

At least 3 div/ns for standard 31 phosphor; at least

6 div/ns for optional 11 phosphor (with the

TEKTRONIX C-31-R Camera and OLAROID 10,000

ASA film).

Auto Focus

Automatically maintains beam focus for all intensity

settings. (Intensified zone and EXT Z axis are not

auto-focused).

Graticule

Internal, no parallax. Variable edge-lighting. Markings

for measurement of risetime. Graticule is dark with

illumination off.

Beam Finder

Limits display within graticule area.

External Z-Axis

Risetime 15 ns. Input R 500 T2. +0.2 V (DC to 20 MHz)

blanks trace of average intensity. +2 V (DC to 2 MHz)

blanks maximum intensity trace.

Beam Current Limit

Automatically limits the average beam current to protect

the CRT phosphor. (Limits average current to 20 pA for

sweep rates faster than 50 ms/div; 5 pA for 50 ms/div

and slower sweep rates and for X-Y. Backup system

shuts down power supply if average current reaches

approximately 30 pA.)

©1-5

Specification—485/R485 Service

CALIBRATOR

Two-Frequency Fast-Rise Calibrator

Accuracies +15°C to +35°C —15°C to +55°C

5 V amplitude to

1 Mft load 0.5% 1%

0.5 V amplitude to

50 ft ±0.5% load 1% 1.5%

50 mA amplitude to

optional BNC acces

sory current loop 1% 1.5%

Selectable Frequency

of 1 MHz and 1 kHz 0.25% 0.5%

Output Resistance

450 S2

Risetime

ositive edge into 50 £1, less than 1 ns. Overshoot and

ringing less than 2% into 50 at 1 GHz bandwidth.

1 kHz Duty Cycle

49.8% to 50.2%

OTHER CHARACTERISTICS

Signal Outputs

ositive gates from both time bases (approximately 4 V),

and a positive-going Sawtooth from Time Base A

(approximately 10 V). Gates and Sawtooth are approxi

mately 0.5 V amplitude into 50 S2.

Power Requirement

Two-position line voltage selector 115 V (90 V to

136 V) and 230 V (180 V to 272 V) 48 to 440 Hz. 60

watts maximum at 115 V and 60 Hz. 0.9 A maximum at

115 V and 60 Hz. Line fuse: 3 A fast.

Cooling

Quiet, filtered, forced-air ventilation. Fan speed

increases smoothly with increasing ambient temperature.

ENVIRONMENTAL CHARACTERISTICS

Ambient Temperature

Operating: —15°Cto+55°C

Storage: — 35°C to +75°C

Altitude

Operating: to 15,000 feet. Maximum allowable ambient

temperature decreased by 1°C per 1000 feet from 5,000

to 15,000 feet.

Nonoperating: to 50,000 feet.

Vibration5

Operating: 15 minutes along each of the three axis,

0.025 inch peak-to-peak displacement (4 g’s at 55 Hz)

10 to 55 to 10 Hz in 1-minute cycles.

Shock5

Operating and Nonoperating: 30 g's, one half sine,

11-ms duration, 2 shocks per axis in each direction for a

total of 12 shocks.

Electromagnetic Interference

(With 485 EMI modification option 4). Meets inter

ference requirements of MIL-1-618D: power line

conducted, 150 kHz to 25 MHz; radiated, 150 kHz to

GHz.

Humidity

Operating and Storage: 5 cycles (120 hours) to 95%

relative humidity referenced to MIL-E-16400F (par.

4.5.9 through 4.5.9.5.1, class 4).

Dimensions and Weight

Height: 6 and 9/16 inches.

Width: (with handle) 12 inches.

Depth (including panel cover): 18 and 1/2 inches.

Depth (handle extended): 20 and 5/8 inches.

Net weight (without accessory case and panel cover): 21

pounds.

Net weight (with panel cover, accessory case and

accessories): 24 pounds.

Domestic shipping weight: 31 pounds.

Export-packed weight: 42 pounds.

SR485 strapped to table, not mounted in rack.

1-6

Section 2—485/R485 Service

OPERATING INFORMATION

General

To effectively use the 485, the operation and capabilities

of the instrument must be known. This section describes

the operation of the controls and connections and gives

first-time and general operating information.

PRELIMINARY INFORMATION

Operating Voltage

WARNING fe

This instrument is designed for o eration from a

ower source with its neutral at or near earth

(ground) otential with a se arate safety-earth

conductor. It is not intended for o eration from two

hases of a multi- hase system, or across the legs of a

single- hase, three-wire system.

The 485 can be operated from either a 115 V or 230 V

nominal line voltage source, or a 220 V external battery

pack. The Line Voltage Selector switch on the rear panel

converts this instrument from one operating voltage to the

other.

Operating Temperature

The 485 can be operated where the ambient air

temperature is between —15°C and +55°C (+5°F and

+131°F). This instrument can be stored in ambient

temperatures between —55°C and +75°C (—67°F and

+167°F). After storage at temperatures beyond the opera

ting limits, allow the chassis temperature to come within

the operating limits before power is applied.

The 485 is cooled by air entering through the air filter

on the rear panel and exiting through the holes on the sides.

Adequate clearance must be provided at these locations.

Allow at least one inch clearance behind the air filter and at

least one inch on the sides.

A thermal cutout in this instrument provides thermal

protection and disconnects the power to the instrument if

the internal temperature exceeds a safe operating level.

ower is automatically restored when the temperature

returns to a safe level. Clean the air filter periodically; a

dirty filter prevents adequate air flow into the instrument.

CONTROLS AND CONNECTORS

ower Cord Conductor Identification

Conductor Color Alternate Color

Ungrounded (Line) Brown Black

Grounded (Neutral) Blue White

Grounding (Earthing) Green-Yellow Green-Yellow

CAUTION

This instrument may be damaged if o erated with the

Line Voltage Selector switch set to incorrect osi

tions for the line voltage a lied.

115 V 90-136 V

230 V 180-272 V

General

The major controls and connectors for operation of the

485 are located on the front panel of the instrument. Some

auxiliary functions are provided on the side, top, bottom

and rear panel. To make full use of the capabilities of this

instrument, the operator should be familiar with the

function and use of each of these controls and connectors.

A brief description of each control and connector is given

here.

Front Panel

OWER ushbutton Turns instrument on or off.

CAL 5 V Connector BNC connector for square-wave

voltage calibrator output signal.

The 485 is designed to be used with a three-wire AC

power system. If the three to two-wire adapter is used to

connect this instrument to a two-wire AC power system, be

sure to connect the ground lead of the adapter to earth

(ground). Failure to complete the ground system may allow

;he chassis of this instrument to be elevated above ground

potential and pose a shock hazard.

FREQ ushbutton Selects one of two frequencies (1

kHz or 1 MHz) for the fast-rise

calibrator signal.

INTENSITY Control Controls intensity of writing beam.

B INTENSITY rovides additional intensity con-

Control trol for the B SWEE .

REV. C. MAR. 1977 2-1