Chevrolet DB90 Series, Руководство по обслуживанию

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Sec. 6Y -144
A. C. GENERATING SYSTEM (NON-INTEGRAL TYPE)
P O T E N T IO M E T E R Z E N E R
(R -4 ) D IO D E (D 2
V O L T A G E
D IV ID E R F IE LD
R E S IS T O R D IS C H A R G E \ B A C K B IA S
(R - 3 ) D IO D E (D - 3 ) \ D IO D E (D 1
D R IV E R
C O L L E C T O R
R E S IS T O R !R I
F E E D - B A C K
C A P A C IT O R (C l )
C A P A C I T O R (C-Ti
PANEL BOARD (UNDERSIDE)
CIRCUITS W ITHIN REGULATOR
Figure 3 5 —U nder Side o f Panel Board A ssem bly
norm al room tem perature. If regulator is being se t
on the v eh icle, voltage should be se t 0.1 volt low er
than the middle range given in "Specifications” to
com pensate for the higher am bient tem perature.
7. Rem ove the panel board, heat sink and ter m ­
inal assem b ly from regulator c a se . In sert lev er
into potentiom eter so that it w ill mate with middle
p osition of adjustment s lo ts in regulator c a se . U se
a soldering iron to m elt adjustment le v e r into
potentiom eter.
8. A ssem b le regulator components into the
c a se and attach cover plate.
REGULATOR REPAIR
(MODEL 9000590)
To check the regulator (fig. 32) for defective
com ponents, proceed as follow s:
1. R em ove the bottom plate fro m th e regulator
(fig. 33).
2. Rem ove the three panel board attaching
sc r e w s identified by arrow s (fig. 33), and lift the
a ssem b ly from the housing.
3. To aid in r e a sse m b ly , note or make any
identifying m arkings on the two tr a n sisto r s and
th eir resp ectiv e locations on the panel board and
heat sink a ssem b ly (fig. 35).
4. Note the insulators between the tra n sisto r s
and the heat sink, and the in su lators separating the
heat sink from the panel board (fig. 35).
5. Rem ove the tr a n sisto r attaching sc r e w s,
and sep arate the tr a n sisto r s and heat sink from
the panel board.
With the tr a n sisto r s separated from the a s ­
sem b ly, an ohm m eter may be used to check the
tr a n sisto r s and com ponents on the panel board for
d efects. An ohm m eter having a l!£-volt c e ll, which
i s the type usually found in s e r v ic e sta tio n s, is
recom m ended. The low range sc a le on the ohm­
m eter should be used.
If a component part of the panel board i s found
to be faulty, it should be replaced b efore p roceed ­
ing with the rem aining ch eck s. A 25-w att soldering
gun is recom m ended, and a 60% tin, 40% lead sold er
should be used when resold erin g. Avoid e x c e s s iv e
heat which may damage the panel board. Chip away
any epoxy involved, and apply new epoxy which is
com m ercially available. The component parts are
identified in figu res 34 and 35.
In order to check the panel board assem b ly,
it is n e c e ssa r y to unsolder the em itte r -b a se r e ­
s is to r at location shown in figure 36.
In a ll of the follow ing checks, connect the ohm ­
m eter a s shown, then r e v e r se ohm m eter lead s to
obtain two readings.
NOTE: R efer to figu res 34 and 35 for id en ti­
fication and location of follow ing components:
FEED-BACK CAPACITOR (C l),
(PART A, Fig. 36)
If both readings a re zero , the capacitor is d e­
fe c tiv e . V isually inspect for open sold ered connec­
tions and broken lead s.
FILTER CAPACITOR (C2),
(PART B , F ig. 36)
If both readings a re zero , the capacitor is de­
fe c tiv e . V isually inspect for open so ld ered connec­
tion s and broken le a d s. To a sse m b le a new cap ac­
itor prop erly, note location of the "+" identifying
mark in figure 35.
SUPPRESSION DIODE (D4),
(PART C, F ig. 36)
If the two readings a re id entical, the diode is
faulty.
CHEVROLET SERIES 70-90 HEAVY DUTY TRUCK SHOP MANUAL SUPPLEMENT