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Noise Problems in Car Head Unit
Noise Problems in Car Head Unit
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Old 30th September 2004, 11:50 AM   #1
fr0st is offline fr0st
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Join Date: Dec 2002
Location: Australia
Default Noise Problems in Car Head Unit

I just recently bought a new (well second hand) head unit.
Unknown to me, it has a noise problem
It only happens with the CD player and you can quite easily hear the noise of the main motor. There are two others (face plate motor and cd loading motor) that create the noise aswell but to a lesser extent.
Has anyone conquered this before?
I put some 0.1uf caps accross the motors but it didn't do anything noticable.
Would this be the motors being to noisy or the regulator to the DAC & output opamp playing up?

Thanks for your help
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Old 20th August 2017, 01:26 PM   #2
zinda is offline zinda  United States
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Join Date: Nov 2010
The motors mounted to a board or do they have wires running to them from the main board? Noise is heard through preamp outputs or through speaker level outputs, noise in both directions (forward and reverse operations). what if you play a disc and then open the door, do you hear both noises getting louder or just 1 noise that stays without change? What happens if you push slightly on the door to make it work harder, does the noise increase? Does the motor have good power (forceful) sometimes as brushes wear on motors like that (if they have brushes) they will tend to start to make contact out of center on the shafts and they will have some contact on parts of the pick-up contacts at the same time as it spins past. A sorter piece will tend to shift it's contact to a point that is touching sooner than it will normally and eventually it will catch and bend as it runs in reverse or forward depending on which side has worn out.

This is the only obvious explanation i can think of that would make it become audible just by thinking of it in a mechanical sense, otherwise routing of the wires may be to blame or improper ground, but with motors that run F&R you have no constant ground and arcing at the contact point on the shaft would be a good place to start. try replacing the motor with any other motor just don't install it, leave it outside the case and jumper wires to it while you disconnect the noisy one and see if it goes away. This is what i would try then you know if you need to find a new motor or not, easiest thing to check and easiest to replace. I doubt that any caps will stop noises from actual arcing and quick shorts that might occur inside a motor. You should see some strange readings as well with you meter while they are running and some current spikes if they are arcing or shorting. Since they might stop at a point where the contact on the shafts could be on the same section of plates it could send the voltage back into the circuit even if it's just 1 motor. The CD motor is the only one that's not reversible, plus it gets the most use, do discs cue up fast? I would check it out first by disconnecting it and see if the noise still comes from the other 2 motors.

Some spin motors are mounted directly to the boards and are much harder to work with while others are mounted using 2 tiny screws and 2 wires, hopefully you have the wired type just for ease of testing. They are both easy to replace as long as you can find the board mounted one with the correct shaft length and the same wiring connector.
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Old 21st August 2017, 08:03 AM   #3
percival007 is offline percival007  England
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Join Date: Sep 2007
Make, Model?

Check for broken 0Volt Tracks on the PCB's.

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Old 24th August 2017, 11:30 PM   #4
phase is offline phase  United States
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Join Date: Oct 2004
Somehow I'm thinking the op either fixed it or replaced the entire car since 2004 when they posted that...
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Old 25th August 2017, 06:58 AM   #5
percival007 is offline percival007  England
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Join Date: Sep 2007
Originally Posted by phase View Post
Somehow I'm thinking the op either fixed it or replaced the entire car since 2004 when they posted that...

Never even noticed !!!

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