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HEWLETT
PACKARD

SERVICE INFORMATION FROM HEWLETT-PACKARD
1st Quarter 1996

Failure Modes o Qigital ICs
b
Jim BechtoldlHewlett-Packard Open Output Bond cause all inputs driven by that output
to float to a bad level since 1.5 volts is
In the case of an open output bond (Fig- less than the high threshold level of 2.0
In order to troubleshoot efficiently, it
ure l),the inputs driven by that output volts and greater than the low thresh-
is important to understand the type of
are left to float. In TTL and DTL circuits old level of .4 volt. In TTL and DTL, a
failures found in digitalcircuits.IC fail-
a floating input rises to approximately floating input is interpreted as a high
ures can be categorized into two main
1.4 to 1.5 volts and usually has the ef- level. Thus the effect will be that these
classes; internal IC failure and a failure
fect on circuit operation as a high logic inputs will respond to this bad level as
in the circuit external to the IC.
level. Thus an open output bond will though it were a static high signal.
Internal Failures
There are four types of failures that can
occur internally to an IC. These are:
An open bond on either an input or
output
A short between an input or output
and Vcc or ground
A short between two pins (neither
of which are Vcc or ground)
A failure in the internal circuitry (of-
ten called the steering circuitry) of
the IC

External Failures
In addition to these four failures inter-
nal to an IC, there are four failures that
can occur in the circuit external to the
IC. These are:
A short between a node and Vcc or
ground
A short between two nodes (neither
of which are Vcc or ground)
An open signal path
A failure of an analog component

1
Effects on Circuit Operation DTL INPUTS AS A HIGH STATE

The first failure internal to an IC men-
tioned was an open bond on either an
input or output. This failure has a dif- Figure 1. The Effect of an Open Output Bond Upon Circuit Operation. An open output
ferent effect depending upon whether bond allows all inputs driven by that output to float to a "bad level." This level is usually
it is an open output bond or an open interpreted as a logic high state by the inputs. Thus the inputs driven by an open output
input bond. bond will respond as though a static logic high signal was applied.

Pub. NO. 5964-6004E 0 Hewlelt-Packard 1996
WWW.HPARCHIVE.COM
Open Input Bond
In the case of an open input bond (Fig-
ure 2), we find that the open circuit
blocks the signal from entering the IC
0 OTHER IC INPUTS chip. The input on the chip is thus al-
lowed to float and will respond as
though it were a static high signal. It is
TO OTHER important to realize that since the open
IC INPUTS occurs inside the IC, the digital signal
driving this input will be unaffected by
the open and will appear normal when
looking at input pin A (Figure 2). The
TO OTHER IC INPUTS effect will be to block this signal inside
the IC and the resulting IC operation
will be as though the input were a static
high.

Short Between
SIGNALS AT POINTS A AND 8: Input/Output/Vcc/Ground
5v I A short between an input or output

"L!X!LG-
ov
and Vcc or ground has the effect of
holding all signal lines connected to
that input or output either high (in the

B ""1
ov
1.4V = "BAD LEVEL"
IS INTERPRETED BY l T L INPUTS
AS A HIGH STATE
case of a short to Vcc) or low (if
shorted to ground) (Figure 3). In many
cases, this will cause expected signal
activity at points beyond the short to
disappear and thus this type of fail-
ure is catastrophic in terms of circuit
operation.

Figure 2. The Effect of an Open Input Bond Upon Circuit Operation. An open bond on an Short Between Two Pins
input has the effect of blocking the input signal from reaching the chip and allows the
input of the chip to float to a "bad level." Thus even though the signal can be viewed at an A short between two pins is not as
external point such as Point A, the input of the chip responds t o the "bad level" as though straightforward to analyze as the short
it were a static high level. to Vcc or ground. When two pins are
shorted the outputs driving those pins
oppose each other when one attempts
to pull the pins high while the other
attempts to pull them low (Figure 4).
In this situation the output attempting
to go high will supply current through
the upper saturated transistor of its to-
tem pole output stage while the out-
OTHER IC INPUTS put attempting to go low will sink this
current through the saturated lower
transistor of its totem pole output stage.
TO OTHER The net effect is that the short will be
IC INPUTS pulled to a low state by the saturated
transistor to ground. Whenever both
outputs attempt to go high simulta-
neously or to go low simultaneously,
OTHER IC INPUTS the shorted pins will respond properly.
But whenever one output attempts to
go low the short will constrained to be
low.

Failure of Internal Circuitry
Figure 3 The Effect of a Short Between an Input or Output and Vcc or Gnd. A 1 signal lines
. 1 The fourth failure internal to an IC is a
connected t o Point A are held in the high state. All signal lines connected to Point B are failure of the internal steering circuitry
held in the low state. of the IC (Figure 5). This has the effect

2 BENCH BRIEFS 1ST QUARTER 1996
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Figure 5. The Effect of a Failure of the In-
ternal Circuitry of the IC Upon Circuit Op-
eration. A failure of the steering circuitry
of an IC will either cause the output to be
in a static high state or a static low state.

Figure 6. The Effect of an Open in the Cir-
cuit External to an IC. All inputs attached
to the node at Point A will be driven prop-
erly. All inputs to the right of the open
(Point B) will be left to float to a "bad level"
and will therefore look like a static high
state.

guishable from a short internal to the
IC. Both will cause the signal lines con-
nected to the node to either always high
(for shorts to Vcc) or always low (for
Figure 4. Short Between Two Pins. The error effect of a short between two pins occurs shorts to ground). When this type of
when the outputs driving those pins attempt to pull the short to opposite states. In this failure is encountered only a very close
case, the output attempting to pull the node high will be supplying current while the output physical examination of the circuit will
attempting to pull the node low is a saturated transistor to ground and will be sinking the reveal if the failure is external to the IC.
current. The saturated transistor to ground will thus pull the node to a low state. An open signal path in the circuit has a
similar effect as an open output bond

r of permanently turning on either the
upper transistor of the output totem
pole thus locking the output in the high
blocks the signal flow and has a cata-
strophic effect upon circuit operation.
driving the node (Figure 6). All inputs
to the right of the open will be allowed
to float to a bad level and will thus ap-
pear as a static high level in circuit op-
External Failures
state or turning on the lower transistor eration. Those inputs to the left of the
of the totem pole thus locking the out- A short between a node and Vcc or open will be unaffected by the open
put in the low state. Thus this failure ground external to the IC is indistin- and will thus respond as expected. 0

1ST QUARTER 1996 BENCH BRIEFS 3
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Table 1. Logic analyzers and digitizing oscilloscopes to be inspected/
Safety-Related repaired for potential electric shock.

Service Notes Senaf Numbers Ot
PSSN Number
Service Notes from Hewlett-I'ackard l660A-02-S
relating to personal safety and possible
equipment damage are of vital impor-
tance to our customers. To make you
more aware of these important notes, 1661A-024
they are printed on paper with a red
border, and the service note number
has an "-S" suffix.In order to make you
immediately aware of any potential
1662A 1662A-02-S
safety problems, we are re-highlighting
safety-related service notes here with
a brief description of each problem.
Also, in order to draw your attention
to safety-related service notes in the 1663A 1663A-02-5
service note index, each safety-related
service note is highlighted with a con-
trasting color.
1660AS-02-S

HP 85942A
Video Signal
1661AS 1661AS-02-S
Monitor
Serial Numbers Affected: 1662AS 1662AS-02-S US34510145 / US34510209
OOOOUOOOOO /3512U00160 US35240101/ US35240212

Situation: 1663AS 1663AS-024 US34510156/US34510184

These instruments have two wires that US35240101/ US35240156
come out of the power supply line 1660C 166OC-01-S US35350101/ US35350137
module and go to the power supply
1661C US35350101 / US35350168
assembly. With the current routing
these wires pass close to capacitor C25 I662C 1662C-01-S US35310101 / US35310155
on the power supply assembly. The US35310101 / US35310137
1663C 1663C-01-S
wires are properly insulated; however,
a break in the insulation could conceiv- I660CS 166OCS-01-S US35350101/ US35350187
ably result in a safety problem. This is 1661CS 1661CS-01-S US35350101/ US35350152
a MINIMALrisk, but is noted here as a
product reliability improvement. For 1662CS 1662CS-01-S US35350101/ US35350136
more information, request safety ser- 1663CS 1663CS-01-S US35310101/US35310118
vice note 8942A-01-S from HI' First as
document id 6492. 1664A 1664A-01-S US34390180 / US34390199
US35240101 / US35240249
1670A 1670A-01-S US35340101/US353401 12
1671A 1671A-01-S US35340101/ US35340111
~

1672A 1672A-01-S US35340101/ US35340109
54501A 54501A-06-S 32511416271/ 3251A16271
3251A16418 / 3251A16418
US34510113 / US34510295
54502A 54502A-07-S 3251A06549 / 3251A06549
us345101 17 / us34510219

4 BENCH BRIEFS 1ST QUARTER 1996
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Table 1. (continued)
HP E7080N81N82A
Semiconductor
Test Systems
Serial Numbers Affected:
4504A-03-S US34510122 / US34510271 All systems.
4510B 4510B-03-S 3218A01007 / 3218A01007 A potentially faulty primary AC wire
4512B 4512B-03-S 3218AOO822 / 3218A00822 connection can result in over heating
of system power connections to the
4520A 4520A-02-S US34360585 / US34360898 point of melting. For more information,
US35240101 / US35240168 request safety service note E7080A/
81A/82A-Ol-S from HI' First as docu-
US35300101 / US35300363
ment id 6510.
US35480101 / US35480232
14522A-024 3443A00304 / 3443A00304
HP 16xx Logic Anayzers
3414A00380 / 3414A00380 and HP 545xx Digitizing
3414A00388 / 3414A00388 Oscilloscopes
US34360139 / US34360438 Model Numbers and
US35240101 / US35240128 Serial Numbers Affected:
US35300101 / US35300204 See Table 1.
US35480102 / US35480198 Situation:
j4540A j4540A-02-S US34360193 / US34360427 The condition for possible electric
shock results from a potential short
US352401 10 / US35240122
within the line filter assembly. The fault
US35300104 / US35300204 can be caused by solder fragments
within the line filter moving and short-
US35480101 / US35480138
ing the line to earth ground. This con-
j4542A j4542A-02-S 341 5A00678 I3415A00678 dition may result in an electrical shock
US34360177 / US34360597
by elevating the instrument to a haz-
ardous voltage if the safety ground is
US35240109 / US352401 19 faulty or is disconnected.
US35300103 / US35300194
US35480101 / US35480145 Hewlett-I'ackard strongly recommends
54520C 5452OC-02-S I US35130124 / US35130159 that you return the instrument imme-
diately to the nearest HI' Customer
Repair Center for inspection, and if re-
US35300101 / US353001 18 quired, repair at no charge. For more
information, you may order a safety
service note document from HP First.
54522C 54522C-02-3 US35020103 / US35020120 For the logic analyzers, order docu-
ment id 6386; for the digitizing oscillo-
scopes, order document id 6410. 0

54540C

US35300101 / US35300156
US35480101 / US35480127
4542C 54542C-02-3 US35020106 / US35020230
US35240103 / US35240142
US35300101 /US35300251
US35480101 / US35480174

1ST QUARTER 1996 BENCH BRIEFS 5
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1996 Bench Briefs' Instrument
Service Note Index
HP FIRST (208)344-4809
T & M Instrument Section - Press 4
T & M Service Notes - Press 2
Enter the Password - 76683

SN SN Abstract HP FIRST
Type No. Document ID No.
MA 10887A-02 Performance upgrade to 1 m/s slew rate capability 6383
MR 11757B-03 Mod corrects error in CCIR dispersive fade mrgn algor 6384
MR 117588-03 Mod corrects error in CCIR dispersive fade mrgn algor 6385
MR 1660AS-01 Instructions on reloading SIW to correct Flash ROM failure 6132
PS I~xxX-XX-S Logic Analyzers. Potentially def line filter may cause shock hazard 6386
MR 3245A-01A Mod to correct the square wave symmetry test specification 6387
10 34401A-06 Display assy replacement requires compatible F/W 6388
IO 3561A-10 A91 replaces A90, requiring A99 modification 6389
MR 37717B-03 Inst fails to power-up due to PSU module prob 6390
MR 4155A-02 New power supply prevents shut-down failures 61 13
IO 4286A-01 Bit switch settings of the A1 CPU board 6391
MR 4286A-02 F/W upgrade corrects AUTOREC-S / CALREC-C problem 6392
MR 438A-13 Mod eliminates measurement instability 6393
IO 5071A-04 FAQ about the 507 1A internal batteries 6394
MR 5071A-05 A1 1 failure can cause loss of internal battery capacity 6395
MR 5071A-06 Mod to prevent A12 DC-to-DC converter input failure 6396
MR 5071A-07 Nylon barrel retrofit prevents AI 1 damage 6397

r
MA 5328A-43 Mod reduces TBOut error in Opt 040 or 041 units 6398
MA 5328B-05 Mod reduces TBOut error in Opt 040 or 04 1 units 6399
MR 5347A-10 Replacement Teflon barrel guide for fused BNC connector 6400
MR 5348A-10 Replacement Teflon barrel guide for fused BNC connector 640 I
MR 5350B-08 Replacement Teflon barrel guide for fused BNC connector 6402
IO 54121A-02B TDR system specification change 6403
IO 54123A-01 TDR system specification change 6404
IO 54124A-01 TDR system specification change 6405
IO 5452OC-03 How to set the screen saver feature 6406
IO 54522C-03 How to set the screen saver feature 6407
IO 5454OC-03 How to set the screen saver feature 6408
10 54542C-03 How to set the screen saver feature 6409
PS 545xxx-xx-s Digitizing Scopes. Potentially def line filter may cause shock hazard 6410
IO 54600B-03 New attenuator cover design 641 1
IO 54600B-04 New calibration routine for voltage measurement accuracy 6412
IO 54600B-05 New text limits for horizontal delta-t and (delta-t)"-l 6413
IO 54601B-03 New attenuator cover design 6414
IO 54601B-04 New calibration routine for voltage measurement accuracy 6415
10 54601B-05 New test limits for horizontal delta-t and (delta-t)"-l 6416
IO 54502B-03 New attenuator cover design 6417
IO 54602B-04 New calibration routine for voltage measurement accuracy 6418
10 54602B-05 New test limits for horizontal delta-t and (delta-t)"-l 6419
10 546038-02 New attenuator cover design 6420
IO 546038-03 New calibration routine for voltage measurement accuracy 642 1
1
0 54603B-04 New test limits for horizontal delta-t and (delta-t)"-l 6422
1
0 54610B-03 New calibration routine for voltage measurement accuracy 6423
1
0 54610B-04 New test limits for horizontal delta-t and (delta+l 6424
IO 54610B-05 Internal trigger specification change 6425
IO 54753A-01 TDR system specification change 6426
IO
MR
MA
54754A-01
55 17AIBICID-02
55 17B/C/D-03
TDR system specification change
Recommended repair of sampler assy
6427
63 I6 f
Replace fast-blow with slow-blow fuse 6428
MR 5518A-02 Recommended repair of sampler assy 6429
MA 5519A/B-01 Upgrade increased slew rate capability 6430
IO 6051A-01A Rec procedure for fan speed adjustment 5684

6 BENCH BRIEFS 1ST QUARTER 1996
WWW.HPARCHIVE.COM
SN SN Abstract HP FIRST
Type No. Document ID No.
MR 6545A-01 Replace capacitor C418 to prevent failures 643 1
IO 6573A-01 Recommended rep1 parts for FETs Q901 and Q902 6432
10 6574A-01 Recommended rep1 parts for FETs Q901 and Q902 6433
IO 6575A-02 Recommended rep1 parts for FETs Q901 and Q902 6434
MR 66101A-03 New F/W corrects status before delay problem 6435
MR 66101A-04 New F/W corrects OCP occurring before Output off 6436
MR 66101A-05 New F/W makes List Mode work from the keyboard 6437
MR 66102A-02 New F/W corrects status before delay problem 6438
MR 66102A-03 New F/W corrects OCP occurring before Output off 6439
MR 66102A-04 New F/W makes List Mode work from the keyboard 6440
MR 66103A-02 New F/W corrects status before delay problem 644 1
MR 66103A-03 New F/W corrects OCP occurring before Output off 6442
MR 66103A-04 New F/W makes List Mode work from the keyboard 6443
MR 66104A-03 New F/W corrects status before delay problem 6444
MR 66104A-04 New F/W corrects OCP occurring before Output off 6445
MR 66104A-05 New F/W makes List Mode work from the keyboard 6446
MR 66105A-03 New F/W corrects status before delay problem 6447
MR 66105A-04 New F/W corrects OCP occurring before Output off 6448
MR 66105A-05 New F/W makes List Mode work from the keyboard 6449
MR 66106A-02 New F/W corrects status before delay problem 6450
MR 66106A-03 New F/W corrects OCP occurring before Output off 645 1
MR 66106A-04 New F/W makes List Mode work from the keyboard 6452
MR 6645A-02 Replace capacitor C418 to prevent failures 6453
IO 6673A-03 Recommended rep1 parts for FETs Q901 and Q902 6454
10 6674A-03 Recommended rep1 parts for FETs Q901 and 4902 6455
10 6675A-04 Recommended rep1 parts for FETs Q901 and Q902 6456
10 6682A-01 Recommended rep1 parts for FETs Q901 and Q902 6457
IO 6683A-01 Recommended rep1 parts for FETs Q901 and Q902 6458
IO 6684A-01 Recommended rep1 parts for FETs Q901 and Q902 6459
MA 70820A-05 New probe power fuse replacements enhance service 6460
MR 70908A-25 New adjustment S/W reduces SYTFMD discrim unlock errors 646 1
MR 83751A-01 Inspection and replmnt of rubber air dam attached to fan 6462
MR 83752A-01 Inspection and replmnt of rubber air dam attached to fan 6463
MR 83752B-01 Inspection and replmnt of rubber air dam attached to fan 6464
IO 8444A-07 Recommended wiring when line switch is replaced 6465
IO 8445A-02 Recommended wiring when line switch is replaced 6466
MR 85422E-04 EPROM F/W upgrade corrects stepped measurements 6467
MR 85462A-04 EPROM F/W upgrade corrects stepped measurements 6468
IO 856OE-11 VCO adjmnt for later "1x6" A15 RF assemblies 6469
MR 856OE-13 Intermittent flashing display intensity 6470
10 8561E-08 VCO adjmnt for later "1x6" A15 RF assemblies 647 1
MR 8561E-10 Intermittent flashing display intensity 6472
MR 8563E-10A Possible frequency response drift 6473
IO 8563E-12 VCO adjmnt for later "1x6" A15 RF assemblies 6474
MR 8563E-13 Intermittent flashing display intensity 6475
MR 8564E-04A Possible frequency response drift 6476
10 8564E-06 VCO adjmnt for later "1x6" A15 RF assemblies 6477
MR 8564E-07 Intermittent flashing display intensity 6478
MR 8565E-04A Possible frequency response drift 6479
IO 85658-06 VCO adjmnt for later "1x6" AI5 RF assemblies 6480
MR 8565E-07 Intermittent flashing display intensity 6481
IO 85669-42 Recommended RF section fan motor replacement 6482
IO 8567A-18 Recommended RF section fan motor replacement 6483
10 8568B-35 Recommended RF section fan motor replacement 6484
MR 859OL-04 New F/W Rev K 95.09.14 corrects previous problems 6485
MR 8591C-07 New FIW Rev K 95.09.14 corrects previous problems 6486

-7 MR
MR
MR
8591E-08
8591E-09
8592L-04
Mod corrects overshoot problem in power vs time meas
New F/W Rev K 95.09.14 corrects previous problems
New F/W Rev K 95.09.14 corrects previous problems
6487
6488
6489
MR 8593E-10 Mod corrects overshoot problem in power vs time meas 6490
MR 8593E-13 New F/W Rev K 95.09.14 corrects previous problems 649 1
SA 85942A-01-S Line module wire rerouting prvnts possible safety prob 6492

1ST QUARTER 1996 BENCH BRIEFS 7
WWW.HPARCHIVE.COM
SN SN Abstract HP FIRST
Type No. Document ID No.
MR
MR
8594E-10
8594E-11
Mod corrects overshoot problem in power vs time meas
New FIW Rev K 95.09.14 corrects previous problems
6493
6494
I"
4

MR 8595E-10 Mod corrects overshoot problem in power vs time meas 6495
MR 8595E-11 New F/W Rev K 95.09.14 corrects previous problems 6496
MR 8596E-10 Mod corrects overshoot problem in power vs time meas 6497
MR 85968-1 1 New F/W Rev K 95.09.14 corrects previous problems 6498
MA 875 1A-01A How to install Option 001 into std HP 875 1A 6499
MR 8920DTS-02A New installation card corrects SYS-CONN program bugs 6363
MR 8920DTS-04 New installation card corrects system calibration 6500
MA 89410-01H HP 89410 Firmware revision history 5710
MR 894 1OA-08 Mod corrects intermittent calibration failures 6501
MR 8970B-08 Ground wiring error at DET BNC connector 6502
MR 8970B-09 Defective ferrite beads on transistor leads 6503
MR E36 1OA-04 Mod elims V trans above output set during turn-off 6504
MR E361 1A-05 Mod elims V trans above output set during turn-off 6505
MR E36 12A-03 Mod elims V trans above output set during turn-off 6506
PS E395 IA-01-S For Info Only. Repair procedure/policy elims shock hazard 6166
IO E4208AB-01 How to take care of BSTS floptical drive 6507
IO E4220A-01 New HIL-PS/2 Converter replacement requires new cables 6508
MR E5 1OOAB-0 1 Mod corrects marker target search problem 6509
SA E7080A/81A/82A-01-S Semicon Test Sys. Faulty twist-lock AC connectors may cause shockifire 6510

~

Service Note Types
10 Information Only SA Safety
MA Modification Available PS Priority Safety
MR Modification Recommended

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Santa Clara, CA
Permit No.
1st Quarter 1996
Volume 36 No. 1
information from
Packard Company

To obtain a qualification form for a free
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Reader comments or technical article
contributions are welcomed.
Please send them to the
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f
Editor: Jim Bechtold
Hewlett-Packard
All rights reserved Permission to reprint Bench Briefs granled upon written request lo the Editor Printed in U.S.A.

8 BENCH BRIEFS 1ST QUARTER 1996
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