Stereo problem

Archives of Posts to the NZ MX5 List back in 2005
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Mikkels
Need, more, 5-ing, time....
Need, more, 5-ing, time....
Posts: 140
Joined: Sun Jul 02, 2006 9:04 pm

Stereo problem

Post by Mikkels » Wed Dec 21, 2005 9:36 pm

Hi Guys

I have an issue with my stero in my 5. About two months ago
the headrest speakers original started making a high pitched
sound that rose and fell with engine RPM. Dead annoying so
I figured I needed new speakers. I replaced with the
warehouse speakers. All good for six weeks then suddenly I
have the sound back again.

What gives?

Don
1990 NA with a 1.8 conversion SOLD
2005 NC Limited edition 2470/3500 6MT

MadMaz
Need, more, 5-ing, time....
Need, more, 5-ing, time....
Posts: 100
Joined: Thu May 18, 2006 10:56 pm
Location: Pukekohe

Stereo problem

Post by MadMaz » Wed Dec 21, 2005 10:02 pm

Hi Don

It's likely not be an issue with the speakers themselves.

A high pitched sound that rises and falls in car speakers is related to
alternator load. When under heavy load (such as the lights on, cooling fan
right
up and/or AC on) it's common to hear a whine through speakers matched to
engine speed. Have you ever seen & heard rally car sequences on TV where
whine is heard in the intercom system varying with engine speed? Their high
output 150 + amp alternator units emit a strong field that's picked up by the
coils in the headsets.

First thing I'd do is to check the condition of your battery - if it's crook
the alternator will be made to work hard all the time because of the
increased resistance - if no joy check the regulator out on the alternator -
an auto electrician has all the gear to do this job.

Cheers
Mark
Firm Believer in 98 Go Juice - Go for it!

Grant
Need, more, 5-ing, time....
Need, more, 5-ing, time....
Posts: 175
Joined: Thu May 18, 2006 9:41 pm
Location: Sunny Blenheim

Stereo problem

Post by Grant » Wed Dec 21, 2005 10:30 pm

Another common reason for alternator whine in any radio is poor earthing.
This can be caused by loose earth nuts, clamps, bolts etc. and maybe at the
antenna to body connection. As the alternators wear with age, the output is
more likely to generate whine as well. A faulty diode in the alternator is a
very common source of noise. This is a job for an auto electrician to repair.
The speakers will not be the cause but they needed to be replaced anyway.
Is the noise there at all times or does it vary with the volume setting. Is
the noise on the radio only (AM or FM) or is it there when using the CD or
tape player (or whatever it has). If the noise is there on the radio only,
does it go away when removing the antenna? If it's on the radio only, and
then only with the antenna connected you might have a faulty alternator
suppressor capacitor. Try a replacement.

Grant.
Red 2006 NC Tiptronic
FIX A PC

poison
Keep calm, Forum Moderator here.
Keep calm, Forum Moderator here.
Posts: 530
Joined: Sun Jun 11, 2006 7:47 pm
Location: JAFA Land

Stereo problem

Post by poison » Wed Dec 21, 2005 10:34 pm

The Warehouse, The Warehouse, Where everyone returns their bargain...

I'm going with the battery/alternator too...

Gazza
"PO1SON"
:twisted: Gazda in the white HOT Mazda :twisted:

MadMaz
Need, more, 5-ing, time....
Need, more, 5-ing, time....
Posts: 100
Joined: Thu May 18, 2006 10:56 pm
Location: Pukekohe

Stereo problem

Post by MadMaz » Wed Dec 21, 2005 11:07 pm

Hey Gazza

Re The Warehouse I know exactly what you mean - bought a large Transonic TV
from there once and it blew up only 3 months later.

A wag I know said this: "The Warehouse - Halfway between the Ship
and the Tip".

Cheers
Mark
Firm Believer in 98 Go Juice - Go for it!

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