Blaupunkt Velocity V250 Owner's Manual page 18

TROUBLE-SHOOTING GUIDE
.
No power (blue remote turn-on
light is off)
Power but no sound (blue
remote turn-on light is on)
I. No sound from one channel
or entire side
Very low sound level
Power amplifier turns on and off 0
repeatedly (Motor boating)
Amp sounds fine but gets
very warm to the touch
Amplifier turns off during
loud passages or is distorted
Amplifier turn-on/off pops or
noises
Crackling noise on AM and FM
radio, but not on tape or cd.
Varies with accelerator but is
present at all times.
(This is "radiated" noise)
IO. Whining noise (alternator whine)
occurs while engine is running
and varies in pitch with engine
speed (this noise VARIES with . . 0
radio's volume setting}.
occurs while engine is running
and varies in pitch with engine
speed {this noise DOES NOT
vary with radio's volume
setting}.
18
PROBABLE CAUSE & SOLUTIONS
Check connections to the amplifier's + 12 volt, Ground, and remote lines
l
Verify the appropriate voltages are at their terminals (1 l-1 5 VDC).
.
Check the main power connection at the battery.
.
Check fuse in power line. If fuse is blown, replace it. If it continues to
blow, see your Blaupunkt dealer.
.
Disconnect all speakers and try to power up unit.
speaker short is probable.
.
Check all RCA input cables and speaker output cables.
l
Test the speaker with a VOM to verify > 1 ohm loads per channel.
Check radio balance and fader control positions.
.
Check loudspeaker connections.
.
Check cd changer connections (if applicable).
.
Check radio balance and fader control positions.
.
Check amplifier's input gain control setting - adjust for higher output
levels if possible.
.
Head unit may have extremely low output voltage. A step-up voltage
Make sure connections at battery are tight.
.
Check battery voltage at amp using VOM; it should be 1 l-1 5 VDC.
.
Check all radio and amplifier ground connections.
.
Input gain control is set too high; lower input level accordingly.
Verify that speaker load impedances are > 1 ohms per channel.
.
Verify that the mounting location allows for free air movement around the
amp. The largest area should be above the unit since heat rises.
l Input stage being severely overdriven. Lower input gain.
Verify that speaker load impedances are > 1 ohms per channel.
l
.
Verify that one of the speaker outputs is not shorted to the chassis of the
car.
l Disconnect the RCA input lines to the amp and turn amplifier unit on and
off via the Trigger line. If pop goes away, the amp is turning on faster
than the time required for the radio outputs to settle down. A turn on
delay line may be needed.
.
If the noise persists, disconnect the Trigger line from the head unit and
try connecting directly to the battery. If the noise goes away, use a relay
to switch the trigger line from the clean power source.
Make certain the problem is "radiated" noise by placing a portable FM
l
radio near the car engine. If noise is picked up, then it is an automotive
problem and not your system.
.
Make sure the spark plugs and wires are <2 years old; otherwise
replace.
.
Verify that the engine block is grounded to the car chassis, not paint.
.
Verify the hood is ground to chassis. If not, purchase a flexible metal
strap, scrape off paint at the connections, and screw into place.
l Check power connections to be sure they are clean.
Reroute power to the radio so that it runs directly from battery bypassing
l
battery terminal in fuse box.
Check ground connections to be sure surfaces have been scraped clean
for good connections.
Check battery ground connection at chassis to make sure it's clean and
l
tight. Verify that all connections are scraped clean of paint, rust, or
grease.
.
Check radio and amp connections; you may have to relocate amplifier
ground to same point as radio ground.
.
Bypass all equipment between radio and amp (e.g., equalizers, etc.) and
connect directly to amp. If problem goes away, reinsert each componerr
until noise reappears. Logic shows this part is the problem.
Check for "high level ground loops"; turn off and disconnect unit
grounds, one at a time, except for the power amp. Turn system back on
and check for noise after each ground is removed.
Check for RCA shield "signal level ground loops" by disconnecting th
shield of the RCA cable at one end. If noise disappears modify cable
accordingly.
If it now turns on, a