Power Supplies Levels; Power Supplies Jumpers And Locations; Internal Adjustment Procedures; Reference Adjustment - HP 3456A Operating And Service Manual

Service
le
2. If the raw voltages are good, replace the regulator
of the inoperative supply, as given in Table
8-F-2.
3 . I f the raw supply is defective, make sure the rec­
tifiers and filter capacitors are good. Replace, if
defective.
rlbl, 8·F·2. Power Supplill Levell.
p-
s- (AnI S...", I
_ .-
10
+ 33V + 33V +46V <2Vp-p
+
<.8Vp-p
1 5 V + 1 1.5Vto + 30V
- l SV - 1 7.5Vlo -30V < . 8Vp-p
•
5V + 7 V lo + I SV < . SVp-p
- 1 8V - 2 1 V to -33V
f. If the defective power supply is now good, connect
the appropriate load to the supply as given in Table
8-F-2.
g. I f the supply is unable to handle the load, replace
as
the regulator IC given in Table 8-F-2.
h. I f the supply is able to handle the load, the cir­
cuitry which connects to the supply is loading the supply
down. To help isolate the circuitry, open the power sup­
ply jumpers used by the various circuitry. The jumpers
are listed in Table 8-F-3.
reble 8·F·3. Power Supplill Jumpen Ind LOCItion.
p,,,.,
. -�
,.-
S.."ly
+33V .20
+ 1 5V .20
+ 1 5V
.20
1 5V '20
+
+ 1 5V .20
+ 1 5V
.40
- 1 5V .20
- 1 5V .20
- 1 5V .20
MO
- 1 5V .20
- 1 5V
•
+
5V 20
+ 5V .20
5V .20
+
+ 5V
'20
+
5V .40
+
5V '30
- l BV .20
- 1 BV .20
- 1 BV .20
- 1 BV .20
- 1 BV .20
B-F . 1O. REFEREICE TROUBLESHOOTlIG.
8-F- l l , The Reference Voltage Supplies in the 34S6A
are - 12Va, - 12Vb, and + 12V. The - 12Va Supply is
the main reference voltage, and - 12Vb and + 12V are
8-F-2
R", v-
...
.... .. ..
....
tlf
l
.
3k ohms!lW1
A1OU2
220 otwn.!2W1
220 otwn.(2W1 A1OU3
.no
AtOUl
1.5k ohm.(5WJ
lVp-p ohm.OWl AtOU4
J .....
Sdleutic
..... r
3
·
102
1
205 2
30 4 3
507 4,5A,5B
7
·
101 1
206 2
303 3
-
506 4,5A,5B
7
1
·
206 2
301 3
403
4
-
•
7
·
-
1
207 2
302 3
4
·
5
500
referenced to that voltage. To troubleshoot the
reference voltages do the following:
a. Determine which voltage ( - 12Va, - 12Vb, or
+ 12V) supply is defective.
b. I f the - 12Va supply is defective, do the follow­
ing:
I . Make sure the supply is not loaded down by other
circuitry. Do this by lifting jumper A20JMPR503.
I f the supply is good, a component in the other cir­
cuitry is loading down the supply. Refer to
Schematic 2, 3, 4, and 7 for the other circuitry.
2. I f the supply is still defective, make sure
A2OQSOI, CR502, and CR503 are good. Replace
Q50 1 , CR502, or CRS03, if defective.
3. I f the components are good, replace the Reference
Board and readjust the Reference Voltage (go to
Paragraph 8-F-14).
NOTE
Do
not replace any components on the
Ref erence board (A24 or A25), or inac­
curacy to the 3456A will result.
c. I f the - 12Vb andlor + 12V supplies are defective,
do the following:
I . Make sure the + 12V supply is not loaded down by
other circuitry. Do this by lifting jumper
A20JMPRS04. I f the supply is good, a component
in the other circuitry is loading down the supply .
Refer to Schematic 2, 4. and 7 for the other cir­
cuitry. The AID Circuitry (Schematic 4), which
uses this supply, can
A20JMPR4112.
2. I f the supply is still defective, replace A20US05 .
3. If the - 12Vb supply is defective, remove the A20
board. I f the supply is now good, lift jumper
A20JMPR40 1 . I f the supply is now good.
troubleshoot the AID Circuitry. If the supply is
still inoperative, replace A20U504.
B·F·12. INTERNAL AOJUSTMEIT PROCEOURES .
8-F-I3. The rollowing are the 34S6A's Internal Adjust­
ment Procedures. The adjustment in each procedure
must be performed in the order they are presented.
8·F·14. Reference Adjustment
8-F-15. Do this procedure only if the Reference
Assembly (A24 or A2S) has been changed or any com­
ponents in the Reference Circuitry have been replaced
(A20USOS, etc.), Do the following:
a. Press the 3456A's RESET button.
b. Place jumper A20J29 to the ground position and
set all the jumpers located at the right of A20U500 bet­
ween A20J26 and J27, as shown in Figure 8-F-1.
Model 3456A
be
isolated by lifting jumper
-
-