Service Model
8903B
Maintiwancc. diwrihcd hcwin
is
pcrformtd with powcr .sirpplic~i
lo
thtj instrirmcn~
urd
with the protcxYivc covcirJ rcmovcd. Sirch mainlcwuncc shoirld
hc
pcrjbrmcd
only
Iy)
.scIrvicv-
trained pcrsonnd who arc awarc
of‘
tho hazards in volvcd [for
cwimplc,
jirs and ckc-lrical
shock). Whcw maintcwance can
hc
puformtd withoitt powc’s
.siipplicd,
thc powcr
.shoirld
hc
riwovcd.
A
ny inlcrriiption o[(hi. protwtivc (groirnding) condirctor (imidc or oii(sidc
thc
ins~riimcv~t)
or disconnc~clion of’the protrctive earrh lrrminal will crralc
a
potcvliul shock hazard
fhnl
coitld
rcsiilt in pcnonai injirry. Grorrna’ing
onc
conditctor
of‘
a two condrtctor
oitlkt
is
not
si!/jkictil. Whentwr it is likcly [hat rhc
protection
has
hecw
inipaired, thr ins~rirrnc~nl
miist
hc
rnadc inopcrarivc (that is, scciircd against iininttwdd opc.ra(ion).
If
this instrirmcnt is
to
hi>
cnc>rgizcd via an airtotrarr.~formc~r,
niukc
.siirc thul
lhc
uiilo-
transjormcr’s common trrminal is
conneclrd
lo
thc carlh (crminul Oj.thi1 powcis .soitrw.
Capacilors insidc the insfriimtwt can still
he
charged
tww
(f‘tlic
instriimenl
is
disc‘onnc~clrd
.tom its soirrci~
of
sripply.
Make siirt>
[ha(
only
250
voll
jirscr
wilh (he rt7qitirc.n’ rafed cnrrcwt and of‘thc
spi)cl/kd
typc (normal hlow, (imc dclay,
ztc.)
arc
irscd
.for rcyducwncnt.
Do
not
rise
rquirecl
jii.sc3
or short-circiriti’Cj jirscholdcw.
To
do
so
coitld
crcate a .shock or jirs hazard.
Do
not
itnplirg any h0ard.r in Ihc
A
iidio Analyscr
iin1cs.s
the in.~lrir~i(vil
is
iinplirggcd
or
switched
to
OFF.
Some
hoards contain dtvices which can
he
damapcd
jf‘
fhc hoard is
rtvnoved
when
!he powi’r
is
on.
Use
condirctive .foam when rcmoving
MOS
dvvic‘er. jiom
sockds.
Use
care whtw irnpliigging ICs jrom high-grip sockrts.
8-9.
RECOMMENDED
TEST
EQUIPMENT AND ACCESSORIES
Test equipment and test accessories required to maintain the Audio Analyzer are listed in Tables
1-3
and
1-4.
Equipment other than that listed may be used if it meets the listed critical specifications.
8-10.
SERVICE
TOOLS,
AIDS,
AND
INFORMATION
8-1
1.
Service Accessories
The accessory items required for servicing the Audio Analyzer are listed in Table 1-4. Three 44-contact extender
boards
(HP
08901-60084) are required
for
the observation of waveforms and signatures
on
the
A7
assembly.
Two 30-contact extender boards
(HP
08901-60085) are required for the
A3
and
A4
assemblies. One each
of
the 44 and
30
contact extender boards are required for use with the A2, A5, and
A6
assemblies. The Digital
Test/Extender Board
(HP 08903-60018) is required for troubleshooting the A8 Controller/Counter Assembly.
Refer to Figure
8-1.
The conductive polyurethane foam pad
(HP
4208-0094) is required for the protection
of
MOS
devices as cautioned in paragraph 8-8 and Service Sheets BD4 and 14.
8-1
2.
Heat-Staking
Tool
The front-panel pushbutton switches have small plastic pins protruding from the back. These tabs
fit
through
holes in the front-panel printed-circuit board (assembly
Al)
and are melted down to hold the switch in place.
This process is known as heat staking. The heat-staking tool is a standard soldering iron with a special
tip
attached (see Figure 8-2).
8-1
3.
Assembly Locations
Assemblies in the Audio Analyzer are numbered sequentially from front to back as shown
in
Figure
8-3.
Assem-
blies A2 through
A9
have color-coded board extractors.
(For
example, assembly A6
has
a black left extractor
8-2
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