MG MGA Twin Cam Workshop Manual page 168

THE ELECTRICAL EQUIPMENT
N
4
5
0 · 010'· 0·020'
-- + · -
~§ n
7
2
Fig.
N.8
jHechanical selling of the cJII-out
I.
C nt-t\ur :.djtL-ttine screw.
2. Armature rens-ion
sp-ring.
3. 'Follow through'- ·010
IO
.020
in.
4. Slop arm.
Cut-out adjustment
Electrical set1i11g
S. Armature tongue and mov·
ing c.ontact.
6. Armat\tre securing screw.
1. F ixed
conl:let
blade.
If t he regulator is correctly set but the battery is still
not being charged, the cut-out may be out of adj ustmenr.
To check the voltage at which the cut-om OJX'ratcs
remove the control box cover and connect the voilmeter
between terminals
·o•
and 'E'. Start the engine and
slowly increase its
s~ed
until the cut-out con tacts arc
seen to d ose, noting the voltage a t which this occurs.
It should be 12·7 to 13· 3 volts.
If the cut-out
o~rates
outside these limits it will be
necessary to adjust it to within the limits. To do this
slacken the locknut securing the cut-out adjusting screw
(I) (Fig. N.8) and tum the screw in a clockwise d irection
to raise the voltage setting or in an anti-clockwise
directio n to reduce the setting. Turn tbe screw only a
fraction of a turn at a time and then tighten the locknut.
Test after each adjustment by increas ing the engine
s~ed
and not ing the voltmeter readings at the instant
of contact closure. Electrical settings o f the cut-out, like
the regula tor, must be made as quickly as possible
because of the temperature rise effects.
If the cut-out does no t operate there may be a n o~n
circuit in the wiring of the cut-out a nd regulator unit,
in which case the unit should be remo,·ed for examinat ion
or replacement.
Mcchmrica/ serting
If for any reason the cut-out armature bas to be
removed from the frame care must
be
taken to obtain
the correct air-gap settings on reassembly. These can be
obtained as follows.
Slacken the adjusting screw locknut and un.crew the
cut-out adjusting screw until it is well cle<tr of the
armature tension s pi"ing.
G
Slacken the two armature securing serews.
Press the armature squarely down against the cop~r­
sprayed core face a nd retighten the armature securing
screws.
Using a pair of thin-nosed pliers, adjust the gap
between the armature stop arm and the armature tongue
by bending the stop arm. The gap must be ·030 in.
(-762
mm.) when the armature is pressed squarely down
against the core face.
Similarly, the fixed contact blade must bo. bent so that
when the armat ure is pressed squarely down against the
core face there is a ·follow through' of blade deflection
of ·010 to ·020 in. (-254 to ·508 mm.). Sec (3) (Fig. N.8).
Reset th e cut-out adjusting screw in accordance with
the instructions already gi,·cn.
Oeaning c:ontacts
Do not use emery-cloth or a carborundum stone for
cleaning cut-out contacts. Jf the contacts appear dirty,
rough, or burnt, place a strip of fi ne
glass-pa~r
between
the contacts, a nd then, with the contacts closed by hand,
draw the paper through. This should be done two or
three times with the rough side o f the glass--pa~r
towards each contact.
Wipe away all dust o r other fo reign matter, usi ng a
clean, fluffiess cloth moistened with methylated spirits.
Section N.lO
FUSES
Two 35-amp. fuses arc mounted in a separate fuscbox
and are therefore accessible without removing the control
box cover.
Units protected
The units which a re protected by each fuse can readily
be
tdent ified by referring to the wiring diagram o n
page N.2.
BJo,.· n fuses
A blown fuse is indicated by the failure of all the units
protected by it, and is confirmed by examination of the
fuse, which can easily
be
withdrawn from the spring clips.
If it has blown, the fused state o f the wire will be visible
inside the glass tube. Before renewing a blown fuse
ins~t
the wiring of the units that have failed for
evidence of a short circuit o r other faults which may
have caused the fuse to blow, and remedy the cause of
the tro uble.
Seeton N.ll
ELECTRIC HOR N
If tbe born fails or becomes uncertain in its action
it docs not follow that the horn has b roken down. First
N.IJ