HP 547A Service manual

CERTIFICATION
Hewlett-Packard Company certifies that this instrument met its published specifications
at the time of shipment from the factory. Hewlett-Packard Company further certifies that
its calibration measurements are traceable to the United States National Bureau
of
Standards, to the extent allowed by the Bureau's calibration facility, and to the calibration
facilities
of other International Standards Organization members.
WARRANTY AND ASSISTANCE
This Hewlett-Packard product is warranted against defects in materials and workmanship
for a period of one year from the date of shipment. Hewlett-Packard will, at its option,
repair
or replace products which prove to be defective during the warranty period pro-
vided they are returned to Hewlett-Packard, and provided the preventive maintenance
procedures in this manual are followed. Repairs necessitated by misuse
of the product
are not covered by this warranty.
NO OTHER WARRANTIES ARE EXPRESSED OR
IMPLIED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
MERCHANTABILITY AND FITNESS
FOR A PARTICULAR PURPOSE. HEWLETT-
PACKARD
IS NOT LIABLE FOR CONSEQUENTIAL DAMAGES.
Service contracts or customer assistance agreements are available for Hewlett-Packard
products.
For any assistance, contact your nearest Hewlett-Packard Sales and Service Office.
Addresses are provided at the back of this manual.

CURRENT TRACER
547A
OPERATING AND SERVICE MANUAL
SERIAL NUMBER: AOOOS1 and above
This manual refers directly to Model 547A Current Tracers with Serial
numbers A00051.
NEWER INSTRUMENTS
The changes in Current Tracers with Serial numbers higher than A00051
are described in "Change Sheets" included with the manual.
Copyright HEWLETT-PACKARD COMPANY 1976
5301 STEVENS CREEK BLVD., SANTA CLARA, CALIF. 95050
Manual Part No. 00547-90006
Microfiche Part No. 00547-90007
Printed:
JAN 1978
Printed in U.S.A.
FJ/o- HEWLETT
a:t:. PACKARD

Modei547A
TABLE OF CONTENTS
Tide
Page
Scope of Manual . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Instrument Identification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Unpacking and Inspection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Storage and Shipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Operating Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Current Tracer Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Theory of Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Performance Tests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Table
1.
2.
3.
LIST OF TABLES
Page
Model 547A Current Tracer Specifications . .. . . .. . . . . .. . . . .. . . . .. . . . .. . . . .. . . .. . 2
Replaceable Parts list . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Manufacturers Code list ...................................................... 12
Page
ii

Figure
1.
2.
3.
4.
5.
6.
7.
8.
9.
LIST OF FIGURES
Page
HP Model 547A Current Tracer .. ...... . . .. .. . ...... .... . .. .. .. .. .. .. . .. .. . .... 1
Wire-AND Node Fault . . . . . . . . . . . . •. . . •••. •. . . . . . . . . . . . . . . . . . . . . . . •. . . . . . . . . . . 4
Gate-to-Gate Faults . . . . . . •. . . . . . . . . . . . . . . . . . . . •. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Solder-Bridge in Printed-Circuit . . . . . . . . . . . . . . ••. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Multiple Gate Inputs . . . . . . •. . . . . . . . . . . . . •. . •. •. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Exploded View of Current Tracer . . . . . . . . . . . . . . . . . . . . •. . . . . . . . . . •. •. •. . . . . . .. . . 7
Setup
for 1 rnA Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Setup
for 1 A Test .....•.....•............•................................... 10
Schematic Diagram . . . . . . . . . . . . . . . . . . . . . . •••. . . . . . . . . . . . •. . •. . . . . . . . . •. . . . . . . . 13

Model 547A
Page 1
Figure 1. HP Model 547A Current Tracer

SCOPE OF MANUAL
This manual contains information about the Hewlett-Packard 547A Current Tracer. Coverage includes a description
of the instrument, its applications, specifications, instructions in its use, theory of operation, maintenance, perform-
ance tests, adjustments, list of replaceable parts and how to obtain them, component locators, and schematics.
DESCRIPTION
The HP 547A Current Tracer is a hand-held probe which enables the precise localization of low-impedance faults
in electrical systems. The probe senses the magnetic field generated by a pulsing current internal to the circuit or
by current pulses supplied by an external stimulus such as the HP 546A or 10526T Logic Pulsers. Indication of the
presence
of current pulses is provided by lighting the indicator lamp near the Current Tracer tip. Adjustment of
probe sensitivity over the 1 mA
to 1A range is provided by the SENSITIVITY control near the indicator. The probe
is self-contained and requires <75 mA at 4.5V to 18V, from any convenient source.
INSTRUMENT IDENTIFICATION
Hewlett-Packard uses a 6-digit serial number (AOOOOO) to identify the Current Tracer. If the serial number of
your instrument differs from
the serial number(s) on the title page of this manual, there are other differences
between the manual and your instrument. These differences are covered in a "MANUAL CHANGES" sheet
which
is included with the manual.

Model 547A
SPECIFICATIONS
Table 1 lists all specifications for HP Model 547A Current Tracer.
Table 1. Model 547A Current Tracer Specifications
INPUT:
Sensitivity: 1 rnA to 1A
Frequency Response:
light indicates Single-step current transitions: single pulses 2:50 ns in width; pulse trains
to 10 MHz (typically 20 MHz for current pulses 2:10 rnA)
Risetime: Light indicates current transitions with risetimes :>.200 ns at 1 rnA.
POWER SUPPLY REQUIREMENTS:
Voltage: 4.5
to 18 Vdc
Input Current: 95 rnA
Maximum Ripple: ±500 mV above 5 Vdc
Overvoltage Protection: ±25 Vdc for one minute
TEMPERATURE: 0° to 55°C
WEIGHT: 113.4 g (4 oz.) net; Shipping Weight: 170 g (6 oz).
Size Probe body 15.24 em (6 in.); Cable, 110.38 em (47 in.)
Page 2
200 n5 2 1'5 20 1'5 200 1'5
INPUT PULSE RISETIME

APPLICATIONS
The Current Tracer operates on the principle that whatever is driving a low-impedance fault node must be de-
livering
the majority of the current. Tracing the path of this current leads directly to the fault. Prob\ems that are
compatible with this
method are:
a. Shorted inputs of integrated circuits.
b. Solder-bridges
on printed-circuit boards.
c. Shorted
conductors in cables.
d. Shorts
in voltage distribution networks, e.g., Vee-to-ground shorts.
e. Stuck data buses, such
as three state, open-collector, or Hewlett-Packard Interface Bus (HP-IB).
f. Stuck wire-AND structure.
UNPACKING AND INSPECTION
If the shipping carton is damaged, ask that the carrier's agent be present when the Current Tracer is unpacked.
Inspect the instrument for obvious damage such as dents, scratches, etc. if the instrument is damaged or fails to
meet performance tests, notify the carrier and the nearest Hewlett-Packard Sales and Service Office immediately.
Retain
the shipping carton and the padding material for the carrier's inspection. The Sales and Service Office will
arrange for the repair or replacement of the instrument without waiting for the claim against the carrier to be
settled.
STORAGE AND SHIPMENT
To protect valuable electronic equipment during storage or shipment, always use the best packaging methods avail-
able. Your Hewlett-Packard Sales
and Service Office can provide packaging material such as that used for original

Modei547A
Page 3
factory packaging. Contract packaging companies in many cities
can provide dependable custom packaging on
short notice. Environmental conditions during storage and shipment should normally be limited
as follows:
a. Maximum altitude: 25,000 ft.
b. Minimum temperature: -40°F (-40°C).
c. Maximum temperature: +149°F (+65°C).
OPERATING CHARACTERISTICS
Three conditions must be met before the Current Tracer can properly respond to circuit stimulus:
1. The mark on the probe's tip must be aligned along the length of the printed-circuit trace.
2. The probe be held perpendicular to the printed-circuit trace -not at an angle.
3. The printed-circuit trace must be conducting an alternating current, either from an internal source or,
from
an external stimulus such as a Logic Pulser with a rise-time of ~200 ns.
NOTE
The voltage present on the black power supply lead (negative side of supply) is also present on the
tracer's anodized aluminum case. Do not lay the tracer on any grounded area, such as an instrument
chassis, unless the chassis is at the same potential as the black lead. Damage to the power supply
may result.
CURRENT TRACER OPERATION
Use of the Current Tracer is indicated when conventional troubleshooting reveals a low-impedance fal.lft. The
operator aligns the mark on the probe
tip along the length of the printed-circuit trace at the driver and adjusts
the sensitivity control until the indicator lamp just lights. The probe
is then moved along the trace or placed
directly on the terminal points
of the nodes (or IC pins), while observing the indicator light. This method of