Adjustment Procedures; Introduction; Equipment Required; Adjustment Interval - HP 3438A Operating And Service Manual

Model 3438A
SECTION V
ADJUSTMENT PROCEDURES
Section V
5-1. INTRODUCTION. 5-7. PRE-ADJUSTMENT PROCEDURES.
5-2. This section of the manual contains Pre-Adjustment
and Adjustment Procedures.
5-3. EQUIPMENT REQUIRED.
5-4. The Test Equipment required for these Adjustment
Procedures is listed in Table 5-1. Equipment that satisfies
the critical specifications given in the table may be
substituted for a recommended model.
5-5. ADJUSTMENT INTERVAL.
5-6. Adjustment Procedures should be performed at
least once every year to ensure proper calibration of the
Multimeter.
piicwA,,,,,II
T i ~ e ~ e Adjcrsrtnenr Proc~rrlctres are,/br use hy
qual~/ied persotznel on!r.. To avoid elec,rric,al
sl~uc,k, do nor pei-/:form anl, .rervic,ing orher
r/lan rhar contained in [he operaring
insrruc.rions or Perfortnunc,e Tesrs unlc,.ss vou
ore qualj/i'ecl ro do so.
Wear (,lean c,otron g1ove.s n7hen \corking otz
the c,irc,uir hoards or .swirche.s. Cunrat~~inarion
q/~/i'nger,~~rinr.s on i ~ i g h in~pedat~c.epoit~r.s \t,ill
degracle rhe /~c,r/:fort~iunc~e
( J / '
rhr insrrunlc,tzr.
.V.vlon glo1,e.s should nor he ~t.orn d ~ t r l o [he
po.ssihi/irj:
(I,/'
sraric c,harge hcrildup.
The hj,hrid c,ircuirs in rile .Vulrirnerc,r maj. he
pertnanenr!r damaged h!. sraric disc,harge
,frotn a hand or roo1 u5he11 rhe .Vtrlritnertv- is
disassernhled. The, proc,edure.s be lo^. tnusr he
,/bllo~z~ed ro prevc,nr /~o.s.sihle ~latnage.
I . Ground rhe hand ~ ) h i l e di.sassetnhling
a t ~ d 14,orXing on the .V~tliinlt,rer. Conducri~st,
wri.srhand.s (-/I[)- Purr
No. 00970-67900)
are
available ,/or rhis p~rrpose.
2. Arrac,h rile Mulritnerrr C O M rerrnit~al
ro earth ground. Touc,/i all tools ro cwrrh
ground ro ren~ove sraric, c.i~argc,.s ht:fore u.sing
rht7tn on rhe .Ilulritnerer.
3. Use a soldering iron with a groutldc,d rip.
5-8. Disassembly Instructions:
a. Disconnect 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 allow the A3 P C and shield assembly
(HP-1B) to slide forward
%
of a n inch.
d . Disconnect W5 from the A3 P C assembly. W5 is a
green, yellow. orange, red, brown cable connecting A3 to
4 2 (display).
e. Remove the .A3 P C 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
internal A l shield.
5-9. Test Point and Adjustment Locations.
5-10. Fold out and refer t o Figure 5-4. Adjustment
Locator for the remainder of this procedure. 'The
Adjustment Locator shows Test Points. 'Test Jumpers,
Adjustment and Connector locations.
NOTE
The .Mulritnc,rer .shoctld Lvartn up ,for 15
tninures hefbre per/urtning ihe Aclju.srt~~enr
Procedure.
5-11. ADJUSTMENT PROCEDURE.
5-12. Adjustments should be made in the following
sequence:
@ A
+
7 V Power Supply Adjustment (R417).
@
B
U725 Back Gate Bias Adjustment (R603).
@
10 kHz Clock Frequency Adjustment (R9).
@
A C Zero Adjustment (R203).
@
20 11 Range Zero Adjustment (R11
I).