buzzing noise

[wheelpay]

hi.had my zt 190+ now over 1 week,how ever over 80/90mph there is a buzzing noise.sounds like interferierence via the stereo speakers.even with no radio on, i have not a clue what it is or where its coming from.it is constant and does not change with engine revs.
any ideas will be appreciated:shrug:

[klarzy]

hi.had my zt 190+ now over 1 week,how ever over 80/90mph there is a buzzing noise.sounds like interferierence via the stereo speakers.even with no radio on, i have not a clue what it is or where its coming from.it is constant and does not change with engine revs.
any ideas will be appreciated:shrug:

Watching with interest as I have the same, suspect feedback from alternator or signal noise from one of the sensors but want to see if looping the 12 v to the ICE through a ferrous ring would help..

[HarryM1BYT]

hi.had my zt 190+ now over 1 week,how ever over 80/90mph there is a buzzing noise.sounds like interferierence via the stereo speakers.even with no radio on, i have not a clue what it is or where its coming from.it is constant and does not change with engine revs.
any ideas will be appreciated:shrug:

Just to say that interference generated by the ignition or alternator would vary with engine speed, so my best guess would be something (a motor) which runs at a constant speed - fuel pumps run at a more or less constant speed.

Always best to kill interference at source, rather than attempt to stop it getting into equipment.

[RichardRover]

this is a common fault that results from the factory process for fitting the windscreen, to prove the fault get up to motorway speeds where the buzzing starts then use the screen washers, the buzzing should stop as the water blocks the small gaps in the screen fixing compound

[klarzy]

this is a common fault that results from the factory process for fitting the windscreen, to prove the fault get up to motorway speeds where the buzzing starts then use the screen washers, the buzzing should stop as the water blocks the small gaps in the screen fixing compound

Mine can't be that as the noise comes from the speakers and disappears when you turn the radio off.:D

[wheelpay]

sorry not commented been working away,i wll try the washers at 80/90 mph see if its the windscreen making noise,the standard kenwood unit just been changes so ill see if it still happens with pioneer unit, thanks,i will keep you informed

[coab]

Mine does it now after an engine change and its def from the speakers its like a buzzing noise when your cars wireless (radio) suppressor is knackered and I have HI line.:eek:

[klarzy]

In industry we always try to avoid crossing signal cables with power supplies at 90 degrees as the magnetic field generated by the electrons flowing through the power cable can be inducted by the signal cable and cause interferance.
Listning to my own interferance and the increase in volume and pitch with acceleration leads me to think that the alternator (as i have a CDT it is not ignition noise) is the source.
As i did not have this issue on my previouse ICE system in the same car i think i may have either a power and speaker cable crossed in this way or a badly grounded / shielded line.

I will also look at grounding the chassis of the head unit as this sits on plastic and rubber mounts.

Will keep you updated..

[Jim Jamieson]

This may sound odd but have you tried switching off the air-con.

On our diesel when using air-con I can hear a whine as the compressor is working. As soon as you switch it off whine disappears.

[HarryM1BYT]

In industry we always try to avoid crossing signal cables with power supplies at 90 degrees as the magnetic field generated by the electrons flowing through the power cable can be inducted by the signal cable and cause interferance.

If that is true, then you are completely wrong...

To minimize crosstalk between one system and another, so far as is possible it is good advice to arrange cables to cross at 90 deg.

Running cables side by side, parallel maximizes crosstalk, as does having them close together.

The rules for avoiding crosstalk, are -

1. screening
2. separation
3. avoiding parallel runs
4. If they must cross, cross at 90 deg
5. Use of twisted pairs

[klarzy]

Blimey Harry, every Nestle factory in the world must be wired up wrong then as all of our cables run parallel in cable trays...:shrug:
Neither does that bode well for car looms where all of the wiring is taped up in close proximity in parallel runs....
I agree in industry we do screen and separate but I doubt most rovers have shielded wiring, especially on aftermarket ISO adapters etc.

[HarryM1BYT]

Blimey Harry, every Nestle factory in the world must be wired up wrong then as all of our cables run parallel in cable trays...:shrug:
Neither does that bode well for car looms where all of the wiring is taped up in close proximity in parallel runs....
I agree in industry we do screen and separate but I doubt most rovers have shielded wiring, especially on aftermarket ISO adapters etc.

Whilst that may well be true, it remains the absolutely the WRONG way to avoid crosstalk. Suggest you do some research on the subject.

Why might you think simple transformers are wound so input and output windings are in parallel? So that there is maximum transfer of signal from one winding to the other, where it be an audio matching transformer, RF transformer, or mains transformer - the same applies.

Your segregation is a matter of IEE regulations, where signal cables are not necessarily be insulated to the standards for 240 and 415 volts. The IEE Regs care not a jot for crosstalk, between your cables.

Just pointing out that your suggestion of 90 degrees crossing making crosstalk worse, is completely wrong as is who ever taught you that - very basic, first year stuff I'm afraid.

Getting back to your point about signal (LAN?) cables being run alongside mains cables....

LAN cables and phone cables use what is known as twisted pairs - flow and return will use the same single wire each of a twisted pair. The reason for which is rejection of interfering signal and noise. One of the pair maybe picks up some interference, the second of the pair also picks up the same interference, but of opposite polarity - the net result of which is that they cancel out the interfering signal. The more tight the twist, the better the interfering signal is rejected.

Example two - data bus cables on very modern coach systems. Similar idea to our 75's K-BUS system, except much longer cable runs and much more data on the bus. The designer of the system specified a certain twisted pair cable be used on the new coach (local manufacturer to me). The manufacturer chose to use a cheaper cable with less twists per inch. The new coach's systems proved to be very problematical, poor to respond, slow to respond, scrambled data on the bus.

The coach manufacturing company had to rip out all of the data cable and replace it with the correct spec. of cable.

As said, the rules are...

1. screening
2. separation, where interference follows the inverse square law.
3. avoiding parallel runs
4. If they must cross, cross at 90 deg
5. Use of twisted pairs

[wheelpay]

i posted on here last week get buzzing noise at 80/90 mph,even when radio not on,theres a plastic trim bottom of windsceen that had a plastic cap missing,i covered this and tonight after work blast along wrexham bypass,,,, all quiet

[Simondi]

Glad you got it sorted although probably better not to advertise your breaking the limits;)

Thread moved to General forum, redirect left:}

[motmann]

i posted on here last week get buzzing noise at 80/90 mph,even when radio not on,theres a plastic trim bottom of windsceen that had a plastic cap missing,i covered this and tonight after work blast along wrexham bypass,,,, all quiet

Had the same problem when I got my 18t , it had a New windscreen and it had a very small hole in the sealant, the guys on here pointed me in the right direction!

[wheelpay]

covered missing plastic cover un windscreen fascia, noise gone

[Dragrad]

Threads merged as they are related.