Chevrolet 70 Series 1970, Service Manual

Page: 597 / 841

ENGINE ELECTRICAL 6Y-56
EXTERNAL A. C. TERMINALS
F- BRUSH
HOLDER STUD
SLIP RING
END
RECTIFIER
BOLT/ i.
F+ BRUSH
HOLDER STUD
REGULATOR LEAD (WHITE)
1-6257
Figure 11 —Regulator Terminals and Wiring
Connections (TypicalI
REGULATOR VOLTAGE TEST
NOTE: This te s t w ill determ ine whether the
gen erator or regulator is at fault when th ere is
in su fficien t output.
1. D isconnect negative term inal at battery
until ready to sta rt engine.
2. L oosen two b olts and rem ove slip ring end
r e c tifie r co v er (fig.
1 1
).
3. D iscon n ect field lea d from (F -) b rush hold­
er stud (fig.
1 1
).
4 . Connect external ground jum per w ire to
(F -) brush holder stud.
NOTE: Unit is now fu ll-fie ld e d and w ill have
no voltage control.
CAUTION: DO NOT E X C EED 1700
RPM GEN ERATOR SP EED (500-600 EN­
GINE RPM).
5. In sta ll su itab le am m eter in s e r ie s at (G+)
extern al term in al (fig.
1 0
), and v oltm eter a c r o s s
battery te rm in a ls.
NOTE: R em ove a ll external load from the
b attery by turning off a ll a c c e s s o r ie s , w ince with
constant fu ll-fie ld , voltage can ex ceed 15 v o lts.
6
. Connect b attery, sta r t engine and run at id le
sp eed . If th ere is not a p o sitiv e am m eter reading
and battery voltage does not sta r t to r is e in a few
m inutes, p roceed to Step 7.
NOTE: If th ere is a p o sitiv e am m eter reading
and battery voltage does r is e , generator i s good
and regu lator i s faulty. R ep lace regulator a s d e s­
crib ed la te r in th is sectio n and re -r u n output te s t.
CAUTION: DO NOT short or ground
generator terminals.
7. Connect a jum per w ir e from (G+) term in al
(fig. 11) to (F+) brush holder (fig. 10) after rem o v ­
ing ex istin g two w ir e s .
NOTE: L eave ground jumper connected.
8
. R epeat Steps 5 and
6
. If voltage in c r e a s e s
r ep la ce regulator a s d escrib ed la te r in th is s e c ­
tion . If voltage d oes not in c r e a se gen erator is at
fault.
GENERATOR REPLACEMENT
Due to va ria tio n s in design and the equipment
u sed , the rep lacem en t p roced u res w ill vary a cco rd ­
in gly. The rem oval and in stallation in stru ction s
follow ing a re intended only a s a guide. Additional
op eration s may be required on so m e v e h ic le s to
rem ove additional equipm ent to gain a c c e s s to
gen erator, d rive b elt, an d /or b ra ck ets.
GENERATOR REMOVAL
1. D iscon n ect negative battery cable from
battery.
IMPORTANT: It i s im portant that battery neg­
a tiv e term in a l be disconnected s in c e generator
w ill b e dam aged if w iring or term in a ls a r e a c c i­
dentally sh orted or grounded w hile being d iscon ­
nected.
2. R em ove sh ield from generator d rive p u lley.
3. R em ove nuts and w a sh ers from h a rn ess
le a d s at gen erator te r m in a ls. Tag each w ire to aid
in identification, then rem ove lead s fro m term in a ls.
4. L oosen adjusting arm clam p bolt and g en er­
ator to mounting bracket pivot b o lts. M ove g en er­
ator to lo o sen the drive b elt, then rem ove belt
from gen erator p u lley.
5. R em ove adjusting arm clam p bolt and gen­
erator to mounting bracket b o lts, then rem ove
g en erator from v e h ic le .
GENERATOR INSTALLATION
IMPORTANT: B e su re negative battery cable
i s disconnected from battery. F ailu re to disconnect
the b attery cable may re su lt in dam age to the gen­
era to r.
1. P o sitio n gen erator on mounting bracket and
in sta ll gen erator to mounting b racket b o lts and
adjusting arm to gen erator clam p bolt and w a sh ers.
2. P la c e drive b elt over gen erator drive p ulley
and adjust b elt ten sion as explained p rev io u sly .
Tighten mounting bracket pivot b olts and adjust­
m ent arm clam p bolt to torque recom m ended in
"Specifications" at end of th is se c tio n .
CHEVROIET SERIES 70-90 HEAVY DUTY TRUCK SHOP MANUAL