HP 3438A - Test Jumpers and HP-IB Troubleshooting

Section Vlll
Model 3438A
20 V OUT
200 V OUT
1200 V OUT
'The failure is probably associated with the ac to dc
converter.
Example 2:
200
mV 0 UT
2 V IN
20 V OUT
200 V IN
1200 V IN
The failure is probably associated with the post amp x
10
gain.
8-54(b). The functional block diagram can be used to
isolate failures as follows:
Example
I
acV OUT
dcV OUT
0 hms OUT
The failure is probably associated with the input amp of
the a to d converter.
Example 2:
acV OUT
dcV IN
Ohms
1 N
The failure
is probably associated with the ac to dc
converter.
8-55. Disassembly Procedure. Once it has been
established that there is a failure, disassemble the
Multimeter using the following procedure:
a. Remove the Multimeter Power Cord.
b. Remove two top cover fastening screws (back
panel) and remove top cover.
c. Remove five A3 shield mounting screws (back
panel). This will allows the A3 PC and shield assembly
(HP-IB) to slide
forware J/s of an inch.
d. Disconnect W5 from the A3 PC assembly. W5 is a
green, yellow, orange. red, brown cable connecting A3 to
A2 (display).
e. Remove the A3 PC and shield assembly by sliding
the assembly forward and upward. With the Multimeter
front panel facing you, place the A3 PC and shield
assembly to the right side of the Multimeter.
f. Re-connect W5 to the A3 PC assembly.
g. All adjustments can be made without removing the
interval
A1 shield.
8-56. General Troubleshooting Information.
8-57. Test Jumpers. Test jumpers (JM) are
strategically located on the
A1 and A3 PC assemblies to
aid in troubleshooting. In some locations
JM's can be
clipped open for circuit isolation. Table 8-6 lists the A
l
.I M's and their function.
NOTE
TI7e letter J etc.hc.d on the A1 PC a.s.se1nh11,
drnotrs the. J.W c/esi~tiator on the.\c,he~natic,s.
Table 8-6. Test Jumpers.
Usage
Holds
D~splay
Test Only
I
Test Only
When Opened
disconnects
Vsub from Ull, U12, U13
disconnects Vsub from Ull
disconnects Vsub from U12
disconnects +7 V from U2, U3, U4, U5.
U6, U7, U12
disconnects +7 V from U5, U6, U7
disconnects - 7 V from U2, U3, U4, U5.
U6, U7, U12
disconnects - 7 V from U5, U6. U7
JM
Number
JM 1
JM 2
JM 102
JM 103
JM 201
JM 202
JM 203
JM 401
JM 402
JM 403
JM 404
JM 405
JM 406
JM 407
JM 408
Voltage/Signal
External Hold
10 kHz Test
Input Amp Output
Post Amp Output
Slope Amp Output
Comparator Output
Run up Clock
Vdisp Supply
Vsut, -2 V Supply
Vsub -2 V Supply
Vsub -2 V Supply
+ 7 V Supply
+ 7 V Supply
- 7 V Supply
- 7 V Supply