Service Group Summary; Component Reference Designator - HP 3456A Operating And Service Manual

Model 3456A
Make sure the 3456A is turned O f f and
power is removed from the instrument
before removing or installing a printed cir·
cuit board. or damage to the instrument may
result.
Many printed circuit boards in the 3456A
have MOS devices. Care must be taken when
handling the boards.
8·317. Service Group Summary.
8 - 3 1 8 . Service Group
Failures). This group deals mostly with Outguard Logic
Failures. A description of the failure is as follows:
a. Turn·On Failure. A Turn·Dn Failure is present
when the 3456A's Display, Keyboard, and HP-IS is
dead or inoperative. If any of these symptoms are not
present or only dashes ( -
the instrument does not have a turn-on failure.
b. Inoperative Display. An Inoperative Display ap­
plies to all the display digits except, the most significant
digit, the first decimal point, and both polarity in·
dicators.
c. Inoperative Annunciators. An Inoperative An­
nunciator is when any or all annunciators are not work·
ing correctly, including the display's most significant
digit, first decimal point, and both polarity indicators.
d. Inoperative Ke yboard. An Inoperative Keyboard
is when any or all instrument operation cannot be
selected from the keyboard.
e. HP-IB Failure. An Hp·IS failure is when only the
3456A's Remote Operation fails. I f any other failures
are noted, troubleshoot them first.
f. Isolation Logic Failure. An Isolation Logic failure
is normally idnicated when the 34S6A's displays only
dashes ( - - - - - - ) and Self Test #3 fails. Since
both an Inguard Logic and Outguard Isolation Logic
failure can show dashes and can fail test #3, go to Ser­
vice Group A. Paragraph 8·A-34 or Service Group S,
Paragraph 8-8-6 to determine the faulty area.
g. Miscellaneous Failure (Ou/guard onl y). Some
miscellaneous failures can be an inoperative Voltmeter
Complete. External Trigger, and Math.
A (Oulguard Logic
- - - - - ) are displayed,
8-319. Service Group B Unguard Logic Fa
Service Group has troubleshooting information on the
3456A's Inguard Logic and AID Converter. The In­
guard Isolation Logic troubleshooting is also in this ser­
vice group. This group is also selected for certain test
failures (see Paragraph 8·332).
8-320. Senrice Group C (DCY Fa
has troubleshooting on DCV failures, Ratio. and
Analog Filler failures. This group is also for certain test
failures (see Paragraph 8·332).
8-321. Service Group D (Ohms Failures).
group for any Ohms failures, including D.C. Ohms.
The group is also selected for certain test failures (see
Paragraph 8·332).
8-322. Service Group E (ACY Failures).
for any ACV failures. The group is also selected for cer·
tain test failures (see Paragraph 8·332).
8·323. Service Group F (Miscellaneous).
has troubleshooting for the power supplies and internal
Adjustment Procedures. The procedures should only be
used after repair of the 3456A.
8·324. Component Reference Designator.
8·325. The component
where the component is located. For example, compo·
nent A20RlO5 shows that it is located on the A20 board
(assembly). This is shown by the .. A20" in the
designator. The other areas can be determined the same
way (A4OC5, A40 board, etc.).
8·326. The circuitry in which a component on the A20
board is located, can also be determined from the
reference designator. For example, A20RI05 is located
in the Input Switching Circuitry. This is determined by
referring to the first number of the type of component
designation (R for resistor, C for capacitor, etc.). The
first number in this example is " I " , which is the Input
Switching Circuitry. A listing of the different circuitry
and schematic location is given in Table 8·13.
Table 8·13. Component Numbering.
C
Cllll fl ll u nt
IM.lMr
ir
cu
P"fil
Input Switching
2 Ohms Current Source
3 Input Amplifier
AID Converter
4
5 Reference
7
6
Front Panel Calibr.
Range and Function
Control Logic
Service
il ) This
ures .
u e
il r s ) . This group
Use this
Use this group
This group
Reference Designator tells
SCHmltic
try
l_mHr
i
2
3
4
5A,5B
1.2.5A,5B
. , ,
6
1 2 3
8-57