Fluke 9000A-006 User manual

9000A-006
ASYNCHRONOUS SIGNATURE PROBE
Service Manual
P/N 783944
MAY 1986
© 1986, John Fluke Mfg. Co., Inc. All rights reserved. Litho in U.S.A.

WARRANTY
COVERAGE
Fluke warrants the 9000A-006 Asynchronous Signature Probe to be free from defects in material and
workmanship under normal use and service for a period of one (1) year from the date of shipment. This
warranty extends only to the original purchaser and does not apply to any product that has been misused,
altered, or has been subjected to abnormal conditions of operation.
Fluke’s obligations under this warranty is limited to repair or replacement of a product that is returned to an
authorized Service Center within the warranty period, provided that we determine that the product is
defective. If we determine that the failure has been caused by misuse, alteration, or abnormal conditions of
operation, or if the warranty period has expired, we will repair the Probe and bill you for the reasonable repair
cost.
SERVICE
If a failure occurs, send the product, postage prepaid, to the closest Service Center with a description of the
difficulty. Repairs will be made or the product replaced, and it will be returned, transportation prepaid. Fluke
assumes NO risk for damage in transit.
DISCLAIMER
THE FOREGOING WARRANTY IS EXCLUSIVE AND IN LIEU OF ALL OTHER WARRANTIES, EXPRESS
OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY IMPLIED WARRANTY OF MERCHANTABILITY,
FITNESS, OR ADEQUACY FOR ANY PARTICULAR PURPOSE OR USE. FLUKE SHALL NOT BE LIABLE
FOR AND SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES, WHETHER IN CONTRACT, TORT,
OR OTHERWISE.
GETTING ANSWERS AND ADVICE
To enhance your use of this Product, Fluke will be happy to answer your questions about applications and
use. Address all correspondence to: JOHN FLUKE MFG. CO., INC., P.O. BOX C9090, EVERETT,
WASHINGTON 98206, ATTN: Sales Department. European customers should contact FLUKE (Holland) B.V.,
P.O. BOX 5053, 5004 EB, TILBURG, THE NETHERLANDS.
JOHN FLUKE MFG. CO., INC., P.O. BOX C9090, EVERETT, WASHINGTON 98206

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9000A-006 Service
Table of Contents
SECTION TITLE PAGE
1 INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1
1-1. PURPOSE OF THE EQUIPMENT . . . . . . . . . . . . . . . . . . 1-1
1.2 EQUIPMENT DESCRIPTION . . . . . . . . . . . . . . . . . . . . . . 1-2
1.3. General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2
1.4. The Clock Module . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-3
1.5. The Asynchronous Signature Module . . . . . . . . . . . . . . . 1-3
1-6. The Cassette Tape . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-3
1-7. ORGANIZATION OF THIS MANUAL . . . . . . . . . . . . . . 1-3
1-8. SPECIFICATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-3
2 THEORY OF OPERATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1
2-1. INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1
2-2. GENERAL OPERATION . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1
2-3. DETAILED BLOCK,DIAGRAM DESCRIPTION . . . . . . 2-5
2-4. Clock Module . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-5
2-5. Control Section . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-5
2-6. Gate Section . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-8
2-7. CRC Section . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-10
2-8. Events Section . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-11
2-9. Waveform Section . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-12
3 MAINTENANCE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-1
3-1. INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-1
3-2. REQUIRED PERFORMANCE TEST EQUIPMENT . . . . 3-1
3-3. REPAIR PRECAUTIONS . . . . . . . . . . . . . . . . . . . . . . . . . 3-1
3-4. SMD Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-1
3-5. MOS Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-1
3-6. DISASSEMBLY PROCEDURE . . . . . . . . . . . . . . . . . . . . 3-2
3-7. PRELIMINARY TROUBLESHOOTING . . . . . . . . . . . . . 3-3
3-8. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-3
3-9. Module or Troubleshooter Faulty? . . . . . . . . . . . . . . . . . 3-3
3-10. Module or Interface Pod Faulty? . . . . . . . . . . . . . . . . . . . 3-3
3-11. Disconnecting the Signature Module . . . . . . . . . . . . . . . 3-3
3-12. SIGNATURE TROUBLESHOOTING PROCEDURES . . 3-4
3-13. Getting Started . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-4
3-14. How the Stimulus Programs Work . . . . . . . . . . . . . . . . . 3-5

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TABLE OF CONTENTS, continued
SECTION TITLE PAGE
3-15. Test Setup, Defective Unit (UUT) . . . . . . . . . . . . . . . . . . 3-5
3-16. Taking Signatures with the Test Troubleshooter . . . . . . . 3-6
4 LIST OF REPLACEABLE PARTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-1
5 SCHEMATIC DIAGRAMS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-1
TABLE OF CONTENTS 5-1

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List of Tables
TABLE TITLE PAGE
1-1. Asynchronous Signature Probe Option Specifications . . . . . . . . . . . 1-4
2-1. Signature Module Op Codes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-4
3-1. Required Test Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-1
3-2. UUT Test Setup, Control/Gate Sections . . . . . . . . . . . . . . . . . . . . . . 3-6
3-3. Test Troubleshooter Connections . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-6
4-1. 9000A-006 Final Assembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-3
4-2. A1 Main PCA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-7
4-3. Clock Module Assembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-9
4-4. A2 Clock Module PCA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-9
5-1. Signature Module Signatures (with Stimulus Program 1). . . . . . . . . 5-10
5-2. Signature Module Signatures (with Stimulus Program 2). . . . . . . . . 5-11

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List of Illustrations
FIGURE TITLE PAGE
1-1. Elements of the Asynchronous Signature Option . . . . . . . . . . . . . . . 1-2
2-1. Signature Module, General Block Diagram . . . . . . . . . . . . . . . . . . . 2-3
2-2. Control Section Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-6
2-3. Gate Section, Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-9
2-4. CRC Section, Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-11
2-5. Events Section, Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-12
2-6. Waveform Section, Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . 2-13
3-1. Location of Asynchronous Signature Module . . . . . . . . . . . . . . . . . 3-2
4-1. 9000A-006 Final Assembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-4
4-2. A1 Main PCA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-8
4-3. A2 Clock Module PCA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-10
5-1. A1 Main PCA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-3
5-2 A2 Clock Module PCA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-11

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1-1
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Section 1
Introduction
PURPOSE OF THE EQUIPMENT 1-1.
Signature troubleshooting supplements the basic functions of the Troubleshooter. This
method of troubleshooting is used in situations where the test functions of the
Troubleshooter alone do not provide adequate results. This situation usually exists when a
fault occurs in a circuit area that operates asynchronously with respect to the processor. In
this case, the troubleshooter cannot detect the fault since it is able to examine only
processor-synchronous events.
Although the Troubleshooter may not have “visibility” or access into some areas of the
UUT, it is usually able to stimulate all functional areas in a consistent and repetitive
manner, This type of stimulus is required to take meaningful signatures. The ability of the
Troubleshooter to stimulate the UUT makes it an effective tool for signature-type fault
isolation methods.
The Asynchronous Signature Option 9000A-006 provides additional Troubleshooting
capability for the 9000A series Troubleshooters by using signature-type fault-isolation,
events counting, and test-node waveform capture. Control signals from the UUT establish
the signature and allow asynchronous operation with respect to the microprocessor bus
cycle, i.e., the Pod.
The Asynchronous Signature Option takes signatures at UUT test nodes operating at clock
speeds up to 20 MHz. For counting events, the number of data transitions appearing at the
probe are accumulated up to a total of 16,777,215.
A waveform display feature permits the Troubleshooter to display a representation of the
data appearing at the data probe. The waveform feature is useful for determining the time
interval between two signal transitions. The waveform displayed shows the last 640
nanoseconds of data received by the probe before the signature-gathering operation is
terminated. The display shows logic high, logic low, and tri-state levels.
During troubleshooting operations, the Troubleshooter display notifies the operator of all
test conditions and values. The basic functions of the Troubleshooter, in conjunction with
a suitable Interface Pod, provide the necessary stimulus for the UUT during signature
troubleshooting operations.
All of these features may be accessed while operating the Troubleshooter in the immediate
mode by using the keyboard and display. All features may also be accessed by the use of
test programs that pass control and test results through registers.

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EQUIPMENT DESCRIPTION 1-2.
General 1-3.
As shown in Figure 1-1, the Asynchronous Signature option consists of the Asynchronous
Signature Module mounted within the Troubleshooter case, a separate Clock Module that
connects to the Troubleshooter, and operating programs contained on a magnetic tape
cassette. (For the Model 9020A, programs are executed from within the host computer.)
FIGURE 1-1. Elements of the Asynchronous Signature Option

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9000A-006 Service
The Clock Module 1-4.
The Clock Module provides interface and protection between the Troubleshooter and the
UUT. Interface is required to effectively connect the sources of the clock, start, stop, and
enable signals located on the UUT to the input of the Troubleshooter. A fuse in the ground
line provides the necessary protection. An input to the Troubleshooter from the Clock
Module provides an indication of the fuse condition.
The Clock Module connects to the Troubleshooter with a 15-pin connector located below
the front panel of the Troubleshooter. Connection to the UUT is made by up to five clip
leads that protrude from the Clock module. A clip lead is provided for each of the control
signal inputs (start, stop, clock, and enable), and one is provided for the ground connection
to the UUT.
The Asynchronous Signature Module 1-5.
The Asynchronous Signature Module is a printed circuit board located within the
Troubleshooter. It accepts the start, stop, clock, and enable signals from the Clock Module,
and the data stream from the Troubleshooter data probe. The Asynchronous Signature
Module uses these inputs to generate the corresponding signature, event count, and
waveform data. The module sends the calculated signature and event count over the pod
bus to the Troubleshooter for display on the front panel.
In addition to the signature and events count functions, a set of registers within the module
stores the latest 640 nanoseconds of the data stream gathered by the data probe. The
module sends this data to the Troubleshooter for display on the front panel as a waveform.
The Cassette Tape 1-6.
The Asynchronous Signature Option in the models 9005A and 9010A is operated by a
series of programs contained on a magnetic tape cassette. Once the programs are loaded
into the Troubleshooter RAM, operation of the Troubleshooter in the signature mode is
afforded by several front panel keys. Appropriate displays provide the necessary
interaction between the Troubleshooter and the operator during signature operations.
Operation of the 9020A is a function of the host computer or instrument controller.
ORGANIZATION OF THIS MANUAL 1-7.
This manual documents the Asynchronous Signature Option. The manual provides
information for service personnel (Maintenance). Operational and programming
procedures for the basic 9000A Series Troubleshooter are documented in the appropriate
manual(s).
Note
Information for operating and programming the Asynchronous Signature
Probe is available in a separate manual. Order John Fluke Part Number
773259.
SPECIFICATIONS 1-8.
Table 1-1 lists the specifications for the Asynchronous Signature Probe Option.

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1-4
TABLE 1-1. Asynchronous Signature Probe Option Specifications
SYNCHRONIZATION AND CONTROL
Start Event: A selectable positive or negative edge on the Start line, or the Sync signal from
the Interface Pod (when used).
Stop Event: A selectable positive or negative edge on the Stop line, or the Sync signal from
the Interface Pod (when used).
Clock Event: A selectable positive or negative edge, or a combination of both, on the Clock
line; or the Sync signal from the Interface Pod (when used).
Enable Event: A selectable positive or negative level on the Enable line.
ELECTRICAL
Start, Stop, Clock, and Enable lines (through Clock Module):
Impedance: 10 pF/44 kilohms nominal
Threshold: 1.4 volts
Overvoltage: ±15 volts maximum
Clock Module ground lead is fuse-protected
Data Channel: Uses standard data probe supplied with 9000A mainframe
TIMING
Maximum Frequency:
Start, Stop, Clock, and Enable Signals: 20 MHz (50% duty cycle)
Data Signals: 10 MHz (50% duty cycle)
Clock (if stop counter or both-edge modes are used): 10 MHz (50% duty cycle)
Timing Requirements:
Data setup: 20 ns (Data to be valid at least 20 ns before selected clock edge.)
Data hold: 20 ns (Data to be valid at least 20 ns after selected clock edge.)
Start/Stop setup: 25 ns (Start or Stop to be valid at least 25 ns before selected clock edge.)
Enable setup: 20 ns (Enable to be valid at least 20 ns before selected clock edge.)
Enable hold: 5 ns (Enable to be valid at least 5 ns after selected clock edge.)
FUNCTIONS
Nodal Signatures: 4-digit algorithm

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Transition Counting: 24 bits (0 to 16,777,216 counts)
Waveform Capture: 32 consecutive data samples at 20-nanosecond intervals. High, low, and
invalid levels. The 32 samples terminate with the stop event.
SYSTEM COMPATIBILITY
Can be installed in the Fluke 9005A, 9010A, and 9020A mainframes. Cannot be used with 1802 interface pods.
PROGRAM CONTROL
All functions of the Asynchronous Signature Probe Option can be commanded from within a 9010A or 9005A
user program. All data measured by this option may be tested in the program. A test program controlling the
9020A may command all option functions and retrieve measured data.
ENVIRONMENTAL
Storage: -40 to +80 degrees C, RH <75% non-condensing
Operating: 0 to +50 degrees C, RH <75% non-condensing
0 to +40 degrees C, RH <95% non-condensing
TABLE 1-1. Asynchronous Signature Probe Option Specifications (cont)

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2-1
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Section 2
Theory of Operation
INTRODUCTION 2-1.
This section contains two block diagram descriptions of the Asynchronous Signature
Module housed within the case of the 9000A Series Troubleshooter. The first block
diagram description is general; it describes the operating concept of the Signature Module
and its relationship to the Troubleshooter and UUT. The second block diagram description
covers the module in greater detail.
GENERAL OPERATION 2-2.
The main function of the Signature Module is to receive streams of digital data from the
UUT and generate a test result that the Troubleshooter can display as a four- character
hexadecimal value (signature). During operation in the signature mode, the
Troubleshooter uses the data probe to read the data appearing at the test nodes of the UUT,
and it uses the Clock Module to obtain the START, STOP, CLOCK, and ENABLE control
signals.
The START, STOP, and ENABLE signals (plus the pod SYNC signal if selected) establish
a gate time, and generate CLOCK pulses during the gate time. The START, STOP, and
ENABLE signals synchronize the measurement period to the data being read from the
UUT by the data probe. The selected START signal specifies the beginning of the
signature measurement interval (gate time), which should coincide with the beginning of
the test pattern being stimulated within the UUT.
During the measurement interval, the data probe feeds test data through to the data input
of the Signature Module, which accepts the data into three separate sections:
1. CRC (signature) section
2. Events section
3. Waveform section
When the selected STOP edge occurs, the gate time concludes, leaving registers in the
CRC section loaded with the signature of the clocked-in test data, registers in the events
section loaded with the number of selected transitions, and the waveform section registers
loaded with a binary representation of the last 640 nanoseconds of probe data. The
contents of these three sections are available over the pod bus for display by the
Troubleshooter.

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2-2
Figure 2-1 shows that the Signature Module is connected across the pod bus. Connection
to the bus allows the transmission of op codes and data to the module. Connection to the
bus also allows the transmission of signature, events count, waveform data, and module
status back to the Troubleshooter. The module also uses the handshaking signals
(MAINSTAT and PODSTAT) between the Troubleshooter and the Interface Pod.
The Signature Module begins operation when it is selected by the Troubleshooter. To
select the Signature Module, the Troubleshooter provides the MAINSTAT signal and
sends the module turn-on op code over the pod bus. The control section of the module
recognizes the turn-on op code and effectively disconnects the Interface Pod from the pod
bus. The Interface Pod remains disconnected from the pod bus until the Troubleshooter
releases the Signature Module by means of the turn-off op code.
With the Signature Module selected, the control section receives the op codes from the
Troubleshooter and produces the signals necessary to control the various sections of the
module shown in Figure 2-1. For example, op codes supplied by the Trouble- shooter
perform the following operations:
• Place the status of the Signature Module on the pod bus.
• Send control signals to set up the gate section in accordance with the setup selections
previously made on the Troubleshooter.
• Clear the gate section, the CRC section, the events section, and the waveform section,
then arm the gate section in preparation for the START and STOP signals required to
clock in the data from the data probe.
• Place the status of the module on the pod bus during the gate time and when the STOP
signal is received.
• Disarm the gate section to prevent further gate action from subsequent START signals.
• Reset (clear) the gate section.
• Send four step commands to shift the signature data (nibble-by-nibble) on the pod bus.
• Send six step commands to shift the event count data (nibble-by-nibble) on the pod
bus.
• Send sixteen step commands to shift the waveform data (nibble-by-nibble) on the pod
bus.
These Signature Module operations take place when operating the Troubleshooter in the
signature gathering mode and when the READ PROBE key is pressed. The control section
uses each op code listed in Table 2-1 to perform a specific operation. The overall result of
the operations is to take a signature (plus events count and waveform data) and place it on
the pod bus where it can be read by the Troubleshooter.
Figure 2-1 shows the relationship of the control section to the other sections of the module
(which it controls in response to op codes from the Troubleshooter). Figure 2-1 also shows
the control signals from the UUT/ and Clock Module and the path of the test data from the
data probe.

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FIGURE 2-1. Signature Module, General Block Diagram
The START, STOP, CLOCK, and ENABLE signals from the UUT are conditioned by the
Clock Module and applied to the gate section of the module. The gate section also accepts
the pod SYNC signal (produced by the Interface Pod) as a control signal. The main
function of the gate section is to provide gated CLOCK signals to the CRC and events
registers. The source of the CLOCK signals may be the clock lead of the Clock Module, or
the pod SYNC signal, depending upon the selection made during the setup of the
Troubleshooter for signature operation. The control section causes the gate section to
select the correct source of the CLOCK signal in response to op codes sent by the
Troubleshooter.

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2-4
The gate time (during which the gate section produces the gated CLOCK signals) begins
with the selected START signal and ends with the selected STOP signal. The source of the
START signal may be the corresponding lead of the Clock Module (i.e., the UUT) or the
pod SYNC signal. The source of the STOP signal may the corresponding lead of the Clock
Module or the SYNC signal from the interface pod. Selection of the START and STOP
signals is a function of control lines from the control section, which in turn are a result of
op codes sent by the Troubleshooter.
The CRC section generates the l6-bit signature by using the gated CLOCK pulses to
receive the UUT data fed to the module by the data probe. In the absence of the gated
CLOCK signals, the CRC section ignores data from the data probe. The four-bit parallel
output of the CRC section is available to the pod bus (via a transmit buffer) but is not
TABLE 2-1. Signature Module Op Codes
OP
CODE FUNCTION
00 Turn on the Signature Module to the pod bus (precede with delay)
10 ENABLE signal to be from Clock Module
11 ENABLE signal to be held in the high (enabled) state
12 CLOCK signal to be from UUT via Clock Module
13 CLOCK lead CLOCK signal to be SYNC signal from Interface Pod
14 START signal to be from UUT via Clock Module
15 START lead START signal to be SYNC signal from Interface Pod
16 STOP signal to be from UUT via Clock Module STOP lead
17 STOP signal to be SYNC signal from Interface Pod
18 ENABLE signal level to be valid high
19 ENABLE signal level to be valid low
1A CLOCK signal, select rising edge (overridden by op code 30)
1B CLOCK signal, select falling edge (overridden by op code 30)
1C START signal, select rising edge
1D START signal, select falling edge
1E STOP signal, select rising edge
1F STOP signal, select falling edge
28 Disarm (causes the module to ignore START signals)
29 Arm (cause the module to act on START signals)
2A Disable the stop-on-count function (stops on no. of gated CLOCK)
2B Enable the stop-on-count function
2C Event count from start to stop
2D Event count continuously
2F Initialize event counter
30 CLOCK signal, select both edges
40 CLOCK signal, permit the selection of op codes 1A and 1B
5x Load stop-on-count value, where x is the least-significant nibble
6x Load stop-on-count value, where x is the intermediate nibble
7x Load stop-on-count value, where x is the most-significant nibble
80 Notify the module that the next operation will be a read
90 Shift all registers (next data nibble to the output buffer)
BO Clear the signature register (prepare for next gate time)
CO Clear the events counter
DO Clear the waveform register
EO Clear the gate section (prepare for next gate time)
FO Turn off the Signature Module from the pod bus

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placed on the bus until commanded to do so by the Troubleshooter. Since only four bits of
signature data are placed on the pod bus at a time, four read operations are required by the
Troubleshooter to shift all four characters of signature data through the CRC section and
onto the bus.
The events section generates a 24-bit (six hex-digit) count of events (transitions) that take
place in the test data input. Events counting is selected to take place only during the gate-
time, or continuously (free-running mode). Control lines from the control section select
the signal source to be counted and determine whether to count on a continuous basis or
only during the time of the gated signals. The output of the events section is applied in
four-bit parallel form to a parallel load input of the CRC section. As the Troubleshooter
reads the signature from the CRC section, the event section is pulsed to shift its contents
into the CRC section behind the CRC data being shifted onto the pod bus. To read the
entire contents of the event section over the pod bus, the Troubleshooter performs six
more read operations subsequent to the four used to transfer the signature data.
The waveform register receives the serial data fed from the UUT and loads it serially into
a 32-bit shift register. The operation of the shift register is such that it always contains a
binary representation of the last 640 nanoseconds of test data fed from the probe. This test
data can be displayed on the Troubleshooter as a waveform.
The output of the shift register is 4 bits (one nibble) wide, and is available to the
Troubleshooter via the events section, the CRC section, and the pod bus. To read the
contents of the shift register for display, the Troubleshooter first reads the CRC and event
sections. It then commands the control section to issue the necessary shift commands to
place each nibble of waveform data on the pod bus. Once the Troubleshooter has read the
contents of the waveform section, it can display a representative waveform of the last 640
nanoseconds of probe data.
DETAILED BLOCK,DIAGRAM DESCRIPTION 2-3.
Clock Module 2-4.
The primary function of the clock module is to buffer the UUT control signals. Clock
module circuitry consists of four analog comparators, one for each of the start, stop, clock,
and enable signals. The input of each comparator is compared to a 1.4V reference.
Hysteresis is applied to each channel to help reject noise.
Control Section 2-5.
The main functions of the control section are as follows:
• Recognize the turn-on op code from the Troubleshooter.
• Prevent the Interface Pod from receiving the MAINSTAT signal after the turn-on op
code and before the turn-off op code have been received.
• Decode the op codes sent by the Troubleshooter over the pod bus and generate the
corresponding control signals to the gate, CRC, events, and waveform sections.
Figure 2-2 shows the main elements of the control section, with the Troubleshooter/
Interface Pod connections on the left side and the connections to the remainder of the
module on the right side. During operation, the Troubleshooter addresses both the
Interface Pod and the Signature Module as required to fulfill testing requirements.

9000A-006 Service
2-6
The Interface Pod and the Signature Module are both connected to the same I/0 port of the
Troubleshooter, and the Signature Module examines each op code placed on the pod bus
(by the Troubleshooter) to determine if the Signature Module should turn on or if the
Interface Pod should be allowed to respond.
FIGURE 2-2. Control Section Block Diagram