Opel 1900 1973, Service Manual

Page: 613 / 625

RADIO. GT 105
RADIO
G T
CONTENTS
Subject
DESCRIPTION AND OPERATION: (Not Applicable)
DIAGNOSIS:
Radio Trouble Diagnosis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
MAINTENANCE AND ADJUSTMENTS:
Antenna Trimmer Adjustment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
MAJOR REPAIR:
Removing and Installing Radio . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
SPECIFICATIONS: (Not Applicable)
Page No.
DIAGNOSIS
RADIO TROUBLE DIAGNOSIS
Because radio problems are most often repaired at
United Delco authorized warranty repair stations,
the tendency for many dealer servicemen is to
remove the set when a problem is reported, without
any preliminary diagnosis. This results in a large
number of radios showing up as “NO TROUBLE
FOUND” units when received by the warranty re-
pair stations. This indicates that the trouble can
often be corrected without removal of the radio.
The inconvenience to an owner of driving without a
radio while his set is being serviced at a warranty
station can frequently be avoided if the following
quick checks are used to eliminate external radio
system
before removing the radio for re-
pair.
Always determine from the owner the exact nature
of the radio problem as an aid to diagnosis. Knowing
whether the condition is intermittent or constant,
whether it occurs with engine off or running, with
car stationary or moving, will help to pinpoint the
problem. Never turn on radio with speaker discon-
nected.
Radio Inoperative
.
1. Turn on the radio. The dial should light and a
thump should be heard from the speaker.
a. If a thump is heard, go to Step No. 2 for antenna
check.
b. If no thump is heard, the fuse.
(1) If fuse is bad, replace and try radio again. Race
engine and, if fuse blows
the radio and
speaker assembly for repair by trained radio techni-
cian.
(2) If fuse is good, check to that the
receiver interconnecting cable connected securely.
If there is still no thump when the radio is turned on,
remove the receiver and speaker for repair.
2. Check the antenna by substituting with one held
out the car window.
a. If radio is still dead with substitute antenna,
remove the receiver and
for repair.
b. If radio operates near normal with substitute an-
tenna, some part of the car antenna or lead-in is at
fault.
Radio Reception Is Weak
1. Check to see if antenna trimmer is peaked.
a. Position antenna at a of 31 inches.
b. Tune radio to weak station at or near 1400 KHz
on the dial, and turn volume control to maximum.