Question for 850 owners - Brakes versus Radio.

Good morning,
Occasionaly my radio loses power when I apply the brakes on my 1996 850
turbo. Has anyone else experienced this problem. Is there a simple
solution.

Apperciate any help or ideas, Thank-you

Kirk R.

 

Well, the simple solution is to fix whatever is causing the
intermittent break in power.

My guess is that there is either a power or ground wire that is all
but broken or a connector that is very dirty or about to come apart.
Work backwards from the radio and start jiggling wires and
connectors.

 

That's a new one. First thing I'd do is pull each fuse and check for
corrosion, scrubbing off any you find. Next I'd start looking for a loose or
corroded chassis ground. Bad grounding can cause all sorts of electrical
weirdness. I'm not intimately familiar with the 850 series but perhaps the
radio is grounded to something near the brake pedal and the mechanical
flexing when you apply the brakes opens the connection.

 

Yes, but not related with brakes.
It's related with the engine revolutions and the alternator
tension regulator, I presume, when there is a decceleration
of engine revolutions, around 1500 RPM.
It only happens with the radio, not the CD.

Forget it.
I presume it's a tension regulation on the alternator, but
the tension regulator is fine.
The problem remains for Years (always).
Most certainly it's a radio problem due to its features
of radio interference suppressions.

 

Hi,
SOME Volvo radios have a noise feature that raises and lowers the
volume depending on the speed of the car. This feature can be turned off
and on as you wish. Could this be your problem?
Does the radio turn clear off or just drop in volume?
Good luck, Brad

 

Nope.
But those "radios" have a great sound, very loud and
very good.

The radio turns clear, goes off signal, no volume, zero.
Never happens with the heads light on, at night for instance.
It's a voltage problem, when there's a voltage drop due
to low engine reverses.
For instance, 12 volts stopped. Then 13 Volts iddling
and increasing up to 13.8V at 1,500-1,700 RPM, then
keeps 13.8V. The radio doesn't like that, or there is a
problem with the voltage regulator around 1,600 RPM.

 

I really doubt it's a voltage problem. The radio should work fine down to
about 9V at which point the lights would be so dim you could hardly see, and
the problem would be worse with the headlights on.

 

Yes, would be worse with the headlights on.
Maybe I use only CD at night. Actually always CD.
As long the voltage regulator works fine, I don't care about
the radio.
But from times to times it happens, always during day light
as I remember, and at decceleration always. Never noticed
that brakes could have anything with it, why and how?

The radio can work fine down to 9V, but the radio doesn't
like voltage changes, because the radio is fine tunned in
resonance at a gives frequency, and I bet the LC resonante
circuit that tunnes the station doesn't like voltage changes,
because it tunnes automatically, and so on...

Simply forget the problem, there's nothing to fix.
Can't have it all.

 

You can't be serious?

The radio will have a regulated power supply within it, an automotive
electrical system is notoriously filthy. Modern radios don't use a tuned LC
circuit anyway, the tuning will be digitally synthesized.

I'm betting on a loose connection somewhere, if you say the brakes are not
related, it's probably the mechanical motion of slowing down.

There's no way this is a voltage problem though unless the lights are
dimming severely at the same time.

 

Good morning,
It has only happened during the day (so far) so I cannot tell you if the
lights are diming or not. Since it is now happening more often I will pay
more attention to night driving.

Kirk R.

 

Some trouble shooting advice:

If the lights in the radio do NOT dim or go out when this happens, then
it is most likely a problem in the antenna or speakers. The antenna
could have a loose connection. There may be a broken speaker wire or a
loose connection. If it hits both speaker at once, it may be the
speaker ground connection.

If the lights in the radio dim or go out when this happens, it is most
likely problem in the power to the radio. It could be in a fuse, a
ground connection or poor power connection.

Does it only occur when the car is moving and you are decelerating, or
does it even occur when the car is just sitting and you apply the brakes.

If it only occurs when the car is decelerating, then it is probably a
loose connection.

If it also occurs when the car is just sitting, then it is probably a
poor ground connection.

Most 850 radios have tabs on the side so you can pull the radio out. Do
this and see if there is any corrosion on any of the contacts. Push it
in and out several times to see if that helps.

 

Digitally synthesized or not, there is a tuned LC circuit somewhere.
Radio signals are electromagnetic waves that have to be driven
at resonance at a given frequency. Electronically it can only be
done by a matched circuit composed by a series inductor and a
capacitor in resonance, so that "motion" is amplified at that
specific frequency.

A seven years old lose connection, even after several radio removals
to fix the CD in/out system ?

Can't notice anything on any light, not even on the radio.
Nothing lose exists, not even the motorised antenna is lose enough
to be the cause, since it only happens at around 1,600 RPM
de-accelerating, once in every 10 to 20 times it could happen.

The problem remains exactly as it was 7 years ago, since I've
buy the car (850 T5 1996).