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7. REPAIR AND ALIGNMENT
7.1.
1.2.
7.3.
7.4.
7.5.
7.6.
Introduc c ion
Repairs and adjustments on the equipment should be perfomed only
by qualif led technicians to whoa this chapter is addressed. Before
atten|)ting any repairs or adjustnent8 a study of Chapter 5. Techni-
cal Description, is recomended.
Cro89-Slot Screws
The cross-slot screws used to secure the printed circuit boards are
Pozidriv screws. A Po2idriv 8crendriver No. 18hould be used in or-
der to avoid damaging such screws.
Locatin
Subunits and Com Onents
Loc:ation§ of circuit boards in the equipment appear frou the photo-
graphs on pages 8-
to 8-
. I.ocatioas of cotaponents on each cir-
cuit board appear on the component locatioti drawings against the
respective circuit diagrans.
Locatin
Faults
Fault finding. as described in section 7.5. below, i8 aided by test
poiots provided for the purpose of pemitting rapid localization of
faulty circuit boardson the basis of I)C tBeasurement8. Siace not all
types of faulcB can be traced by means of DC measureaenc8, supple-
mentary AC DeagureDents With an oscilloscope nay be required; see
section 7.6.
To facilitate fault finditis oa each individual circuit
board typical volcage8 are listed on the circuit diagrams.
Test Points
Several circuit boards coticaia cue or IIiore te8C points. They are
snail pia-type teminals, colour coded following the standard colour
code in addition to being numbered. Ia the circuit diagrams. teat
points are marked
TP 1.
TP 2
eec., and typical voltages at the
test points are listed there.
The teminals of the circuit boards may to a great extent also be
regarded as test points. Typical voltages are therefore also listed
against relevarlt Cerninals on the circuit diagrans.
If a voltage measured at a test point differg markedly from the listed
value it ig a f airly certain indication that the circuit board in
q`iegtion is faulty, assunitig chat tbe voltages applied to the circtlit
board are the correct ones. This should likeviBe be checked.
AC Voltages
AC voltages listed in the circuit diagrans are typical voltages. Volt-
ages 9pecif led are based on q]eas`irement With an oscillascoE.e having
an input ixpedance of 10 Mohms in pamllel iiith 7 pF. a 8enaitivity
of the order o£ 50 tBV/div and a I requency range of not lees than
DC -S0 RE.
7-I
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