Model 343814 Section
Vlll
8-58. Test Pads.
Logic control states for the A
I
PC
significantly from
zero. troubleshoot the lnput Amplifier
assembly (Hi
=
+
7
V,
Low
=
0
V)
can be evaluated using first.
the test pads.
rable8-7 lists the test pad by number and its
associated function.
8-64.
The gains for the lnput and Post Amplifiers can be
Table 8-7. Test Pads.
8-59. Power Supply.
If the
+
7
V
and/or the -7
V
supply reads low at the test pads, turn SI OFF and re-
check for
+7
V
and -7
V
at a point prior to the Sl. Refer
to schematic no. 4. This will verify if the problem is in the
power supply rather than in the Multimeter circuitry.
Figure 8-10 shows the jumper configuration for the
+
7
V
and -7
V
power supplies.
No.
1
2
3
4
5
8-60.
V~IIH
is the substrate voltage for U
l
I,
U 12. and
U 13. If this voltage is incorrect. individually opening J M
403, JM 404. and JM 402 while monitoring the
VSIIH
voltage will isolate the faulty integrated circuit.
8-61.
A1
and
A2
Troubleshooting.
Usage
Run Up Enable
::;I
pc:pn
FNC Code
MRF Manual Range
Switch Code
8-62. Analog Troubleshooting.
Failures in the
analog circuitry can best be analyzed by studying the
Simplified Analog Schematic, Figure
8-
12.
NOTE
No.
6
7
8
9
10
verified by-stopping the measurement cycie during run-
up. This is accomplished by shorting U 13(35) to ground
during run-up. This stops the controller clock and leaves
the gain selector switches set for run-up. A dcvoltage can
Usage
MRE Manual Range
Switch Code
MRD Manual Range
Switch Code
Digital Ground
Run Down
Compensation
(+)
No Connection
be used in each range to signal trace the stage gain of the
lnput and Post Amplifiers.
8-65. Logic Troubleshooting.
The Multirneter Logic
can best be tested by the following procedure:
a. With
5403 still disconnected-open JM202.
b. Connect the controller (U13) side of JM202 to
.I
M203.
c. The display to indicate all zeros except when a
"Improper" switch combination is selected (Refer to
Section Ill).
8-66. If this test fails, there is a problem in the Logic
portion of the Multimeter. If it passes. the problem is
most likely to be in the Analog portion.
NOTE
The Adjusrtnenr Proc,rclurr tn~i.s/ he
prrf'ortnrcl and rhr Ahhrc~viarrd Per/brtnutlc,r
Tes/ c,otnplr~erl hefirr ussutning rhr
M~ilritnerer has f'ailrd. .Munj* hours
r?/'
rrouhle.shooring (,an ht, \c~aisrc~J her.au.se o/an
ovrrlooked ad;usrtnrrzr.
8-67.
HP-IB
(A3)
Troubleshooting.
8-68. The A3
PC
assembly can best be troubleshot using
the
-hp- 5004A Signature Analyzer (SA) and the
Troubleshooting Flow Charts given in Figure
8-1
1.
8-63. The Input and Post Amplifiers can be isolated by
8-69. Signature Analyzer (SA).
Throughout the
placing a short between the
COM
and Amps input following Flow Chart, the SA switch settings and
terminals. This forces the Multimeter into Auto Zero. connectors will be given except the ground lead
Therefore, the outputs of either Amplifier should be
connection. I'he ground lead is connected to the
GNL)
approximately zero volts. If both amplifiers are offset jumper on the A3 PC assembly for the entire test.
POWER SUPPLY JUMPERS
JM405 JM406
-7v
V
JM407
dM408
I
NOTE
ihl 405THROIIC,H
JM
408
AH6 NOT
6HUPLN
OW
THE
SCtltMATIC DlAGHAMS
I
Figure 8-10. Power Supply Jumpers.
8-9
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