Chevrolet DB90 Series, Service Manual

Page: 143 / 242

Sec. 6Y-137
A. C. GENERATING SYSTEM (NON-INTEGRAL TYPE)
9. Check and adjust the voltage setting on the
low er or s e r ie s contacts as follow s:
Slowly d ecr e a se the 2500 rpm value and ob­
se r v e the voltm eter. When operation changes from
upper to low er contacts, voltm eter reading should
suddenly d ecrea se a few tenths of a volt. Compare
difference in voltage readings with "Specifications”
at end of this sectio n .
IMPORTANT: Always rem ove wiring harness
connector from regulator when rem oving o r in­
sta llin g regulator cover to avoid accidental grounds
and consequent damage to regulator.
10. If voltage operation is erra tic, and if the
regulator cannot be adjusted to a steady value, r e ­
p lace the regulator.
ADJUSTING REGULATOR VOLTAGE
SETTING (WITH 1116374 OR 1116378
REGULATOR)
NOTE: Regulator voltage setting should be
checked as explained previou sly under "Regulator
C ircuit T est - With 1116374 pr 1116378 Regulator."
VOLTAGE SETTING ADJUSTMENT
1. Rem ove a c c e s s plug from regulator cover
and u se a thin-bladed screw d riv er to adjust the
voltage settin g.
2. For an undercharged battery condition,
turn the adjuster clock w ise one notch (0.3 volt) to
in c r e a se the settin g.
NOTE: A fter two notches in each direction
Figure 19—Generator Brush Replacem ent
(M o d el 111 7754 or 111 77871
th ere is a p o sitiv e stop.
3. F or an overcharged battery condition turn
the adjuster counterclockw ise one notch (0.3 volt)
to d ecr e a se the settin g.
4. A fter adjusting the voltage settin g, check for
an im proved battery condition after a se r v ic e p e r ­
iod of reasonable length. If n e c e ssa r y , repeat the
above procedure for a higher or low er setting.
SERVICE OPERATIONS
GENERATOR REPLACEMENT
Due to variations in design and equipment on
v e h ic le s using A.C . gen erators, the replacem ent
p rocedures w ill vary accordingly. The rem oval
and installation in stru ction s follow ing a re intended
only a s a guide. Additional operations w ill be r e ­
quired on som e v e h ic le s to rem ove other equip­
ment to perm it a c c e s s to generator, b e lts, an d /or
brack ets.
GENERATOR REMOVAL
1. D isconnect negative battery cable from the
battery.
CAUTIO N : It is important that bat­
tery negative term inal be disconnected,
since generator will be damaged if wiring
or term inals are accidentally shorted or
grounded while being disconnected.
2. On 4 2 -, 61-, and 62-am p gen erators, d e­
p r e s s lock on connector and pull connector out of
sock et on generator. Pull rubber boot off "BAT"
term in al and rem ove term in al nut. D isconnect w ire
from "GRD" term inal and rem ove w iring clip .
3. L oosen adjusting arm clam p bolt and gen­
erator to mounting bracket pivot b o lts. Move gen­
erator to loosen drive belt(s) and rem ove from
generator pulley.
4. R em ove adjusting arm clamp bolt and gen­
erator to mounting bracket pivot b olts, then r e ­
m ove the generator.
GENERATOR INSTALLATION
IMPORTANT: B e su re negative battery cable
is disconnected from battery. Failure to disconnect
the negative battery cable may resu lt in damage to
the generator.
1. Attach generator to mounting bracket and
in sta ll adjusting arm clamp bolt.
2. P la ce drive belt(s) over generator drive
CHEVROLET SERIES 70-90 HEAVY DUTY TRUCK SHOP MANUAL SUPPLEMENT