HP 3575A Manual page 67

I
Model
3575A
TBO UBLESHOOTING
Additiona.l
checks can
be
peformed
using the
power supply
data listcd
in
Table 5-6.
lf
any
of
the supply
yoltages
are
out
of
tolerance,
troubleshoot
the
conesponding
power
supply
or
regulator circuit by
checking
for
the dc
voltages
shorvn
on the
schematics.
NOTII
All of
the rc& ators on
Al4
ore
directb or iulirectly
referencet)
to
+ 12Vdc.
The +
12 Vclc referance
nuts't,
therefore,
be
properly
acljLtsted
to
estqblisll the
acato(! of
the othcr suppll'
voltages.
1n qddition,
all of
tha lC
regulqtors ofi
Al4
use
+
12 Vd( and -
l2
Vdc ontl
a
failura
in
either
of
these supplics can affect the other
supph,
voltages.
5-89. No
Load Checks. The
Porver
Supply
Asscnrbll,, A14,
is cquipped
with
separatc
input
and
output
connectors to
permit the
supplies to
be checked under no load conditions.
The
2xl0-pin
connector
on the
left-hand
side
of Al.l
receives
uruegulatcd inputs from
the
raw
supplies
on Al5.
The l2-pin cornector on
the
right-hand
side
of
A14
outputs the
regulated voltages
from Al4 to
the
main
Mother Board Assembly, Al7.
5-90.
To
chcck
the
supplies under no load
conditions.
proceed
as
follorvs:
a.
Place
Al4 on a
2Xl0-pin PC
Extender
(-hp-
5060-5987).
Leaye
the l2-pin
output
oonnector
discon-
nected.
b.
Corurect a short clip
lead betwecn
chassis
ground
and
pins l1
and
l2ofthe
12-pio cornrector on
Al4.
c.
Using a
DC voltmeter,
measure the regulated output
voltages
at
pins
4
th'rough 10
of
the
12-pin connector
on
A14.
The dc voltages should bc
as
follows:
Section
V
suppiies.
If
dilflculty is
encountered,
check
suspected
componcnts
with
an ohnteter or
transistor
checker,
rcplace
Al4lCl
and IC2 or
isolate thc
trouble
using an extental
dc
source
as
outlined in
the
followirg
procedurc:
RECOMT,IENDED
EQUIPMENT:
DC Di8ital Voltmeter
(-hp-
Ntodel
34504)
1
l2
Vdc
Variable Power Supply
(hp-
Model
4674)
a.
Check
to
be
sure
that
the
raw
supply
voltages
are
present
at
XAl,lA
pins 9
(+
19
Vdc)
and B
(
l9
Vdc).
b.
Dsconnect one end
of A14Rl.
c.
Place
Al4
on
a
2Xl0
PC
Extender (-hp"
5060-5987).
Lfave the
l:-pin
outpul. cunlector
disc.rnnccted.
d.
Connect a short clip
lead between
chassis
gound
and
pins
I
I
and
l2 of
the l2-pin
connector on
Al4.
e.
Connect
the
DC
Dgital
Voltmeter to pin 9 of
the
I
?-pin connector on
Al4.
f.
Apply
+
12
Vdc from
an exterral power supply
to
pin l0 ol
the l2-pin
conneotor
on
Al4.
g.
Thc DVM
reading should
not
be
-12 V
dc.
If
'
l2 V
dc is
present, leave
the
extcrnal
porver
supply
connscted
ard
troubleshoot the
+ l2
V
rcgulator circuit
by
checking
for
the dc
voltagcs shown on
Schenratic
No. g. If
-
l2 V
dc is
no1 prcsent,
perforDr
the iirlloivilg
steps.
h
Disoonnect the external power
supply and reconnect
AlzlRl.
Dsconncct
one
end
of Al4R8.
i.
Connect the DVM to pin l0 of
the
I
f-pin
conlector
on Al4.
j.
Apply -
l2
Vdc from
an
extunal
power
supply to pin
9
of
the l2-pin
connector on
Al4.
k.
The DVM
reading should
now be
+
12Vdc. If
+12Vdc is
present, leave the
external power
supply
connected
and troubleshoot the - I2 V
regulator
circuil by
checking
for the
dc
voltages
shown
on the
schematics.
if
+
l2
Vdc
is
not
present,
there
are
failures in both regulator
cilcuits.
4
5
6
7
8
I
10
+5V10.02Vdc
- 5.3
V
1 0.1 Vdc
6V1o.o2Vdc
-6Vl0.02Vdc
+ 3.8
V
1 0.1 Vdc
12
V 10.04
Vdc
+'12
v
r
3
mvdc
*
5-91.
Troubleshooting
the
+
12
Due
to
thc
interactiolt
belween
supplies,
it
is sontetinres
di[ficult
*
Adiustable
V
and -
12 V
Supplies.
the+12Vand-12V
to
isolate lailurcs
in
thesc
*
Adjustable (A148
6)
**
Load increases
to
1
.5
A
in Option 001 insiruments and to
2 A
in
Option
002,
OO3 instruments.
Table
5-6.
Power Supply
Ratings.
Supply
T€st
Point
Voltage
Limit
Ripple
{p-pl
L
ine
Regulation
i'115
V
1230V
!
10
%t
Nominal
Current
+ 12
V
*
.12
V
6V(A)
-6V(B)
+5V
-5.3V
+3.8V
ATPl
Pin
6
A7P1 Pin
D
A7P1
Pit
4
A7P1 Pin
21
ATPl
Pin
3
+11.997Vto+12003V
-
1 1
.960 V
to
-
1
2.040
V
5.980
V
ro
6.020
V
-5.980
V
to
6.020 V
+
4.980 V to
+ 5.020
V
-
5.2oo V
to -54oov
+ 3.700 V to
+ 3.900 V 3mV
10.1
mV
r
0.1 mV
10.2
mV
180 mA
180 mA
2OO
mA
20O
mA
35O mA
3O0 mA
5.1
9