pioneer head unit crackles most of the time when engine running, but not when engine

G'day.

I've got a petrol Mav. The old Pioneer CD radio worked fine however decided to update to digital age and got another Pioneer that takes CD, USB, and SD card. I think it also takes 3.5mm jack.

I've had two of them now, and both have crackled when they feel like it. Quite a bit sometimes, not at all otherwise, and never when the ignition is set to ACC.

The thing is, it never crackles on AM or FM radio, only on SD or Ipod or CD.

I've upgraded the earth from what worked with the original unit - still no joy. Same with the positive supply. Even fitted a 20A filter in the supply.

When it is in the mood to crackle, maybe it crackles more when decellerating to a stop, or at idle, then when at speed, but it is hard to pick.

I dunno if it is voltage related, thought it might be given it does not happen when engine is stopped, however connected up a voltmeter, and while the battery is charging after a cold start, the volt meter indicates 14.6, yet no crackle.

It is beginning to get a bit frustrating - any suggestions very welcome

sounds like it might be your alternator ?????

have you still got the original speakers in there?

could be nowoollies, I'll chase up the auto leccie again - I wondered about the internal regulator clicking on and off and upsetting the radio - hence the filter.

AB, the speakers are Pioneers. They would be a few years old and were in the Mav when I bought it.

They used to work ok with the old radio cassette.

Tracking down the cause of noise in the radio can be a real pain.

I would start by checking/cleaning all the vehicle earths, especially the body earth points, (I have heard a story about how radio noise was stopped in one vehicle by running an earth lead to the bonnet).

Normally when alternators are the cause of the noise the sound heard is a whining type noise that increases with engine RPM, you could try fitting a noise suppressor to the main power wire at the alternator.

How's your vehicles ignition system? how old are the plugs, leads, cap and rotor button? these can cause noise, you could also try fitting a noise suppressor to the positive side of the coil.

You could also try disconnecting the aerial from the back of the radio and see if this stops the noise.

Another thing you could try is running the power supply directly from the battery (both power and earth) just temporary run some double insulated 4mm twin from the battery to the radio (connect both the battery back up and accessory wires to power and earth to the radio) and see if this stops the noise. If it does stop the noise a relay will need to be installed when the wiring is done permanently.

Hope this helps.

Good luck with it.

Quote:

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Originally Posted by Yendor

Tracking down the cause of noise in the radio can be a real pain.

I would start by checking/cleaning all the vehicle earths, especially the body earth points, (I have heard a story about how radio noise was stopped in one vehicle by running an earth lead to the bonnet).

Normally when alternators are the cause of the noise the sound heard is a whining type noise that increases with engine RPM, you could try fitting a noise suppressor to the main power wire at the alternator.

How's your vehicles ignition system? how old are the plugs, leads, cap and rotor button? these can cause noise, you could also try fitting a noise suppressor to the positive side of the coil.

You could also try disconnecting the aerial from the back of the radio and see if this stops the noise.

Another thing you could try is running the power supply directly from the battery (both power and earth) just temporary run some double insulated 4mm twin from the battery to the radio (connect both the battery back up and accessory wires to power and earth to the radio) and see if this stops the noise. If it does stop the noise a relay will need to be installed when the wiring is done permanently.

Hope this helps.

Good luck with it.

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Thanks Rod, I'll work through the list and see how I go. The interesting thing is that the AM and FM radio aren't affected by the crackle/pop.

The fact that it goes away when the ignition is on ACC, ie motor not running, does seem to suggest there is some noise coming through somehow.

The leads and plugs are only a couple of thousand ks old. The cap is a bit older. I'm getting an extended rotor, so be interested to see what that changes, if anything

I don't think the problem can be with the head unit itself if you have had the same problem with 2 head units (unless this is a common problem with the Pioneer head units????)

I can only assume the reason for it not to crackle on AM or FM is there is better noise suppression built within the radio circuitry then the CD, USB and SD card side.

You could try disconnecting the alternator by unplugging the 2 plug connector at the alternator, then start the engine (without revving the engine and confirm with your voltmeter that it's not charging) and see if that stops the noise.

thanks Yendor, I'll try that - and sorry for the delay in replying - I've been away for a few weeks, and hadn't thought about this issue for a while.

I think it may be something to do with the charging side of things because while away, I'd drive at a steady 100 kph for ages, and all was good. Slow down for a town, snap crackle and pop, back up to 100 and steady at that, all became nice again.

It's going to the local auto leccie for an aircon service (decided I am too old and inflexible to do it myself any more) and will ask him then.

No worries mate, let us know what they find.

Make sure you run the negative lead coming out of the head unit all the way back to the negative battery terminal this will stop any earth causing noise issues.