3 Series MDO
Mixed Domain Oscilloscope
Service Manual
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Table of Contents
Table of Contents
List of Figures................................................................................................................................................................................v
List of Tables.................................................................................................................................................................................vi
Important safety information........................................................................................................................................................ vii
General safety summary...................................................................................................................................................... vii
Service safety summary........................................................................................................................................................ ix
Terms in the manual.............................................................................................................................................................. ix
Terms on the product.............................................................................................................................................................ix
Symbols on the product......................................................................................................................................................... x
Preface..........................................................................................................................................................................................1
Supported products................................................................................................................................................................1
Replaceable parts.................................................................................................................................................................. 1
Where to find operating information.......................................................................................................................................1
Theory of operation....................................................................................................................................................................... 2
Power supply......................................................................................................................................................................... 3
I/O board................................................................................................................................................................................ 3
Main board and front-end board............................................................................................................................................ 3
Front panel and display..........................................................................................................................................................3
Adjustment procedures................................................................................................................................................................. 4
Adjustment............................................................................................................................................................................. 4
Adjustment interval................................................................................................................................................................ 4
Adjustment after repair...........................................................................................................................................................4
Maintenance..................................................................................................................................................................................5
Preventing ESD..................................................................................................................................................................... 5
Inspection and cleaning......................................................................................................................................................... 5
Exterior cleaning (other than display)............................................................................................................................. 5
Flat panel display cleaning............................................................................................................................................. 6
Interior cleaning.............................................................................................................................................................. 6
Lubrication...................................................................................................................................................................... 7
Returning the instrument for service...............................................................................................................................7
Remove and replace procedures...........................................................................................................................................7
Required equipment....................................................................................................................................................... 8
Remove feet................................................................................................................................................................... 8
Remove handle...............................................................................................................................................................9
Remove rear grill and case.............................................................................................................................................9
Remove handle hub assembly......................................................................................................................................10
Remove rear chassis assembly.................................................................................................................................... 11
Remove the main fan assembly....................................................................................................................................12
Remove the AC line filter.............................................................................................................................................. 13
Remove the power supply assembly............................................................................................................................ 15
Remove the I/O board.................................................................................................................................................. 16
Remove front-panel knobs............................................................................................................................................18
Troubleshooting the 3 Series MDO......................................................................................................................................18
Level of service.............................................................................................................................................................18
Check for common problems........................................................................................................................................18
3 Series MDO Mixed Domain Oscilloscope Service Manual iii
Table of Contents
Equipment required...................................................................................................................................................... 19
Test points.....................................................................................................................................................................19
Troubleshooting flow chart............................................................................................................................................19
Instrument self tests......................................................................................................................................................21
Software updates..........................................................................................................................................................21
After power supply module replacement.......................................................................................................................22
Replaceable parts....................................................................................................................................................................... 23
Parts ordering information....................................................................................................................................................23
Module servicing.................................................................................................................................................................. 23
Abbreviations....................................................................................................................................................................... 23
Using the replaceable parts list............................................................................................................................................23
Rear case.............................................................................................................................................................................24
Rear chassis........................................................................................................................................................................ 26
Front chassis........................................................................................................................................................................28
Front panel and display........................................................................................................................................................30
3 Series MDO Mixed Domain Oscilloscope Service Manual iv
List of Figures
List of Figures
Figure 1: MDO34 block diagram................................................................................................................................................... 2
Figure 2: MDO32 AFE board........................................................................................................................................................ 3
Figure 3: AC line filter cable connections....................................................................................................................................14
Figure 4: AC line filter cable connections....................................................................................................................................16
Figure 5: Primary troubleshooting tree........................................................................................................................................19
Figure 6: AC power supply troubleshooting procedure............................................................................................................... 20
Figure 7: Module isolation troubleshooting procedure................................................................................................................ 21
Figure 8: Rear case exploded view.............................................................................................................................................24
Figure 9: Rear chassis exploded view........................................................................................................................................ 26
Figure 10: Front chassis exploded (rear) view............................................................................................................................ 28
Figure 11: Front panel and display exploded view......................................................................................................................30
3 Series MDO Mixed Domain Oscilloscope Service Manual v
List of Tables
List of Tables
Table 1: External inspection checklist........................................................................................................................................... 6
Table 2: Internal inspection checklist.............................................................................................................................................7
Table 3: Required equipment for removal and replacement......................................................................................................... 8
Table 4: Failure symptoms and possible causes.........................................................................................................................18
Table 5: Parts list column descriptions........................................................................................................................................ 23
Table 6: Rear case...................................................................................................................................................................... 25
Table 7: Rear chassis..................................................................................................................................................................26
Table 8: Front chassis................................................................................................................................................................. 28
Table 9: Front panel and display ................................................................................................................................................ 30
3 Series MDO Mixed Domain Oscilloscope Service Manual vi
Important safety information
Important safety information
This manual contains information and warnings that must be followed by the user for safe operation and to keep the product in a safe
condition.
To safely perform service on this product, see the Service safety summary that follows the General safety summary.
General safety summary
Use the product only as specified. Review the following safety precautions to avoid injury and prevent damage to this product or any
products connected to it. Carefully read all instructions. Retain these instructions for future reference.
This product shall be used in accordance with local and national codes.
For correct and safe operation of the product, it is essential that you follow generally accepted safety procedures in addition to the safety
precautions specified in this manual.
The product is designed to be used by trained personnel only.
Only qualified personnel who are aware of the hazards involved should remove the cover for repair, maintenance, or adjustment.
Before use, always check the product with a known source to be sure it is operating correctly.
This product is not intended for detection of hazardous voltages.
Use personal protective equipment to prevent shock and arc blast injury where hazardous live conductors are exposed.
While using this product, you may need to access other parts of a larger system. Read the safety sections of the other component manuals
for warnings and cautions related to operating the system.
When incorporating this equipment into a system, the safety of that system is the responsibility of the assembler of the system.
To avoid fire or personal injury
Use proper power cord Use only the power cord specified for this product and certified for the country of use. Do not use the
provided power cord for other products.
Ground the product This product is grounded through the grounding conductor of the power cord. To avoid electric shock, the
grounding conductor must be connected to earth ground. Before making connections to the input or output
terminals of the product, ensure that the product is properly grounded. Do not disable the power cord
grounding connection.
Power disconnect The power cord disconnects the product from the power source. See instructions for the location. Do not
position the equipment so that it is difficult to operate the power cord; it must remain accessible to the user
at all times to allow for quick disconnection if needed.
Connect and disconnect
properly
Observe all terminal ratings To avoid fire or shock hazard, observe all rating and markings on the product. Consult the product manual
Do not operate without covers Do not operate this product with covers or panels removed, or with the case open. Hazardous voltage
Avoid exposed circuitry Do not touch exposed connections and components when power is present.
Do not connect or disconnect probes or test leads while they are connected to a voltage source.
Use only insulated voltage probes, test leads, and adapters supplied with the product, or indicated by
Tektronix to be suitable for the product.
for further ratings information before making connections to the product. Do not exceed the Measurement
Category (CAT) rating and voltage or current rating of the lowest rated individual component of a product,
probe, or accessory. Use caution when using 1:1 test leads because the probe tip voltage is directly
transmitted to the product.
Do not float the common terminal.
exposure is possible.
3 Series MDO Mixed Domain Oscilloscope Service Manual vii
Important safety information
Do not operate with suspected
failures
Do not operate in wet/damp
conditions
Do not operate in an explosive
atmosphere
Keep product surfaces clean
and dry
Provide proper ventilation Refer to the installation instructions in the manual for details on installing the product so it has proper
Provide a safe working
environment
If you suspect that there is damage to this product, have it inspected by qualified service personnel.
Disable the product if it is damaged. Do not use the product if it is damaged or operates incorrectly. If in
doubt about safety of the product, turn it off and disconnect the power cord. Clearly mark the product to
prevent its further operation.
Before use, inspect voltage probes, test leads, and accessories for mechanical damage and replace when
damaged. Do not use probes or test leads if they are damaged, if there is exposed metal, or if a wear
indicator shows.
Examine the exterior of the product before you use it. Look for cracks or missing pieces.
Use only specified replacement parts.
Be aware that condensation may occur if a unit is moved from a cold to a warm environment.
Remove the input signals before you clean the product.
ventilation.
Slots and openings are provided for ventilation and should never be covered or otherwise obstructed. Do
not push objects into any of the openings.
Always place the product in a location convenient for viewing the display and indicators.
Avoid improper or prolonged use of keyboards, pointers, and button pads. Improper or prolonged keyboard
or pointer use may result in serious injury.
Be sure your work area meets applicable ergonomic standards. Consult with an ergonomics professional to
avoid stress injuries.
Use care when lifting and carrying the product. This product is provided with a handle or handles for lifting
and carrying.
Use only the Tektronix rackmount hardware specified for this product.
Probes and test leads
Before connecting probes or test leads, connect the power cord from the power connector to a properly grounded power outlet.
Keep fingers behind the protective barrier, protective finger guard, or tactile indicator on the probes.
Remove all probes, test leads and accessories that are not in use.
Use only correct Measurement Category (CAT), voltage, temperature, altitude, and amperage rated probes, test leads, and adapters for
any measurement.
Beware of high voltages Understand the voltage ratings for the probe you are using and do not exceed those ratings. Two ratings are
important to know and understand:
• The maximum measurement voltage from the probe tip to the probe reference lead
• The maximum floating voltage from the probe reference lead to earth ground
These two voltage ratings depend on the probe and your application. Refer to the Specifications section of
the manual for more information.
Warning: To prevent electrical shock, do not exceed the maximum measurement or maximum
floating voltage for the oscilloscope input BNC connector, probe tip, or probe reference lead.
3 Series MDO Mixed Domain Oscilloscope Service Manual viii
Important safety information
Connect and disconnect
properly
Connect and disconnect
properly
Inspect the probe and
accessories
Ground-referenced
oscilloscope use
Connect the probe output to the measurement product before connecting the probe to the circuit under test.
Connect the probe reference lead to the circuit under test before connecting the probe input. Disconnect the
probe input and the probe reference lead from the circuit under test before disconnecting the probe from the
measurement product.
De-energize the circuit under test before connecting or disconnecting the current probe.
Connect the probe reference lead to earth ground only.
Do not connect a current probe to any wire that carries voltages or frequencies above the current probe
voltage rating.
Before each use, inspect probe and accessories for damage (cuts, tears, or defects in the probe body,
accessories, or cable jacket). Do not use if damaged.
Do not float the reference lead of this probe when using with ground-referenced oscilloscopes. The
reference lead must be connected to earth potential (0 V).
Risk assessment warnings and information
Service safety summary
The Service safety summary section contains additional information required to safely perform service on the product. Only qualified
personnel should perform service procedures. Read this Service safety summary and the General safety summary before performing any
service procedures.
To avoid electric shock Do not touch exposed connections.
Do not service alone Do not perform internal service or adjustments of this product unless another person capable of rendering
first aid and resuscitation is present.
Disconnect power To avoid electric shock, switch off the product power and disconnect the power cord from the mains power
before removing any covers or panels, or opening the case for servicing.
Use care when servicing with
power on
Verify safety after repair Always recheck ground continuity and mains dielectric strength after performing a repair.
Dangerous voltages or currents may exist in this product. Disconnect power, remove battery (if applicable),
and disconnect test leads before removing protective panels, soldering, or replacing components.
Terms in the manual
These terms may appear in this manual:
Warning: Warning statements identify conditions or practices that could result in injury or loss of life.
CAUTION: Caution statements identify conditions or practices that could result in damage to this product or other property.
Terms on the product
These terms may appear on the product:
• DANGER indicates an injury hazard immediately accessible as you read the marking.
• WARNING indicates an injury hazard not immediately accessible as you read the marking.
• CAUTION indicates a hazard to property including the product.
3 Series MDO Mixed Domain Oscilloscope Service Manual ix
Symbols on the product
When this symbol is marked on the product, be sure to consult the manual to find out the nature of the potential hazards and
any actions which have to be taken to avoid them. (This symbol may also be used to refer the user to ratings in the manual.)
The following symbols may appear on the product:
``` ``` ```
Important safety information
3 Series MDO Mixed Domain Oscilloscope Service Manual x
Preface
Preface
This manual contains service information for your instrument.
Read the General and Service safety summaries before servicing the product.
Be sure to read the introductions to all procedures. These introductions provide important information needed to perform the service
correctly, safely, and efficiently.
Supported products
This manual contains information that is necessary to service the following products:
• MDO32
• MDO34
Check for a specific product designation in the header at the top of the page, in a heading, table or figure title, or within text. Material that
does not have any specific product designation applies to all products in the manual.
Replaceable parts
This manual refers to any field-replaceable assembly or mechanical part specifically by its name or generically as a replaceable part. In
general, a replaceable part is any circuit board or assembly, or a mechanical part, that is listed in the replaceable parts list that can be
replaced in the field. See Replaceable parts on page 23.
Where to find operating information
For information on installing, operating, and networking the instrument, refer to the online help or user manual that was provided with your
oscilloscope. You can also find the manual at www.tek.com/manuals, by searching for your product.
3 Series MDO Mixed Domain Oscilloscope Service Manual 1
Theory of operation
Theory of operation
This chapter describes the electrical operation of the oscilloscope to the module level. The block diagram shows the oscilloscope module
interconnections.
Figure 1: MDO34 block diagram
3 Series MDO Mixed Domain Oscilloscope Service Manual 2
Theory of operation
The only difference between the MDO34 and MDO32 block diagram is the AFE board.
Figure 2: MDO32 AFE board
Power supply
The Power Supply board converts AC line voltage to +12 V to power for all internal circuits.
I/O board
The I/O board contains USB ports, an Ethernet port (LAN), a HDMI port, an AUX OUT BNC connector, and the AFG generator output
connector.
Main board and front-end board
The Main and Analog boards contain the following functions:
Acquisition system The Acquisition system begins with the analog signal path and ends with a digitized signal in memory. The
signal enters a channel input, and then passes through an attenuator and preamplifier. The analog signal
from each preamplifier goes through a digitizer, and then into acquisition memory. The analog signal from
each preamplifier is also distributed to a trigger circuit. The digital channels pass through the front of the
instrument to the Main board.
Front-end All of the analog inputs are routed to the Front-end board. The analog channels are amplified and
attenuated through the front-end circuitry, and are output to the Main board. The front-end board has a
controller that is used as an I/O controller for the front-end board.
Mezzanine The Mezzanine board converts the +12 V power to some of the other voltages used for the analog and
digital circuitry throughout the system.
Front panel and display
The Front Panel board contains digital logic that reads the front-panel buttons and controls and sends this information to the processor
system on the Main board. The Front Panel board also generates the probe compensation output signal and provides USB ports on the
front panel. The front panel routes the front-end signals from the probe directly to the front-end board.
3 Series MDO Mixed Domain Oscilloscope Service Manual 3
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