Rolls-Royce Corniche - Page 212

Workshop Manuid Rolls-Royce Silver Shadow & Bentley T Series
Chapter Rf
Fault Diagnosis
The Fault Diagnosis deals with minor radio faults only. Should the fault be proved beyond the scope of this
diagnosis, the radio should be returned to
Rolls-Royce Motors Limited, Crewe or London; or to a Distributor whose
facilities include radio servicing.
Symptom I Possible Cause 1 ~ction
1. Receiver dead - no dial
light
2. Receiver dead - dial
illuminated
5. Weak reception
4. Intermittent reception
5. Interference
1. (a) Blown fuse
(b) Faulty fuse holder
2. (a) Aerial lead has an open
circuit or short circuit
(b) Speaker circuit disconnected
3. (a) Radio aerial circuit not
tuned to aerial
(b) Poor aerial
connections
4. (a) Loose aerial
connections
(b) Faulty fuse holder
assembly
5. (a) Faulty speaker(s)
(b) Regulator noise . A 'grating'
sound with
no regular
pattern is an indication of
a faulty suppressor
capacitor
(c) Generator noise. A
whirring sound which rises
in frequency with engine
speed indicates a faulty
suppressor capacitor
(d) Ignition noise. A vibration
or crackle that increases
in frequency as the engine
is accelerated and varies
with engine speed
1. (a) Fit new fuse
(b) Check that the contacts are clean
and the spring pressure adequate
2. (a) Check aerial lead by substitution
and renew aerial lead if this check
rectifies fault
(b) Check connections at speakers and
connecting block
3. (a) Tune by adjustment to 'aerial
trimmer. Adjust the trim until a
setting is reached where the signal,
having increased in strength stops
increasing and further rotation brings
a decrease
(b) Clean and tighten connections
4. (a) Tighten connections
(b) Check fuse holder
5. (a) Adjust balance control to determine
whether any difference in response
of front and rear speakers. Renew
one
or both as necessary.
(b) Check the capacitor by substitution
and renew if necessary
(c) Fit a suppressor capacitor to the
positive output terminal. This
effectively parallels existing
capacitor built into generator
(d) Check the coil capacitor by
substitution and renew if necessary
Check the distributor high-tension
lead knurled nuts
Check sparking plug connections
and spark plug gaps