Alternator whine please help

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bowser22

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Jan 25, 2010
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My psr 500 wasnt loud enough for me at all. I went on ebay and found a decent little amplifer board
2*15 watt @ 4ohm, TA2024 D-class Audio Amplifier Board on eBay.ca (item 230453629892 end time 23-Apr-10 03:19:11 EDT)
I hooked it up to the headphone output of my psr 500 and then connected it to my 2003 p71 cigarette adaptor. It worked great til I started the car and got a hateful whine from the fuel pump and alternator coming through the speaker. I figured out that I can attatch a wire to a ground on the amp board and then touch the other end to the outside of the bnc connector going into the scanner and it will almost dissapear. But not quite, just for peace of mind I have a drilled roof nmo with a comtelco antenna routed through rg58 up to my dash pad then into the psr. Please help. Much appreciated. By the way I also tried grounding the bnc connector to the car, then grounding the amp to the car. Nothings helping:(
 

jim202

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Joined
Mar 7, 2002
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2,644
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New Orleans region
The adding of the ground wire tells me the circuit board might be missing a ground. If you
have a soldering iron, add the jumper. Getting rid of a whine by other means can get
painful in trying this and trying that. In most cases, adding some filter caps on the 12
volt power wire feed will help. What size caps to use will depend on the situation.

Jim




My psr 500 wasnt loud enough for me at all. I went on ebay and found a decent little amplifer board
2*15 watt @ 4ohm, TA2024 D-class Audio Amplifier Board on eBay.ca (item 230453629892 end time 23-Apr-10 03:19:11 EDT)
I hooked it up to the headphone output of my psr 500 and then connected it to my 2003 p71 cigarette adaptor. It worked great til I started the car and got a hateful whine from the fuel pump and alternator coming through the speaker. I figured out that I can attatch a wire to a ground on the amp board and then touch the other end to the outside of the bnc connector going into the scanner and it will almost dissapear. But not quite, just for peace of mind I have a drilled roof nmo with a comtelco antenna routed through rg58 up to my dash pad then into the psr. Please help. Much appreciated. By the way I also tried grounding the bnc connector to the car, then grounding the amp to the car. Nothings helping:(
 

pinetree

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Dec 1, 2003
Messages
411
Location
Felton DE
The way that worked for us who had the same problem with the early CBs was to pur the secondary of a speaker transformer in series with the power lead + . you had to be sure to tape all connections and the unused leads on the transformer. They were sold with a fancy price but the speaker transformer workes just as well.
 

bowser22

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Joined
Jan 25, 2010
Messages
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I was considering putting a filtering cap on the +12 to the amp. Would like to get this to work as the sound coming from the speaker sounds phenominal aside from the whine.
 

Kennrth

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Jul 24, 2006
Messages
143
Location
Bay Shore Long Island NY
Check your car manual. There is a condenser (capacitor) that is usually comes out of the electrical harness under the hood of your car that has one end bolted/screwed to the engine Block. This may need to be replaced. They fail over time because of the heat. This filters out ignition noise.
Can try commercial inline filter -
10A 12V Car Noise Filter - Archos Accessories
If inline filtering cannot remove the alternator wine
You may need to see if there is ripple voltage on your 12Vdc. Oscope is the best way to see this or have your local mechanic look at it. Most alternators have several poles each with an associated internal rectifier. If one of the rectifiers have failed. or winding unbalanced this will cause alternator wine that is extremely difficult to filter out. The solution is a new alternator with clean dc output. This is a common problem.
 
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