A/C Raw Water Pump Causing Stereo Interference

M

max

Member
Joined
Mar 10, 2001
RO Number
3713
Messages
48
I installed a new DC stereo system and as soon as the A/C pump kicks on I get hissing from the speakers. I tried replacing the pump motor but that did not help.

Any way to shield the pump or filter the DC power going to the head unit aND amps?. I tried the RCA cable filters but they did not help.
 
For starters, get a couple of snap together toroid filters and protect the power leads on both the radio and the pump:

Search for: "RadioShack Snap-Together Toroid Choke Core (2-Pack) Catalog #: 2730104"
To use, "open" the toroid, wrap the power leads a few times ( 3 to 5 or so ) around the opened leg, the latch it back up. Test. If satisfied, wrap the whole mess up with electrical tape. ( optional )

For this purpose "any" toroid will help. Try a hamfest if you find one nearby. Many toroids will appear as a a 1.5 inch ring. Simply feed the power lead through several times. Latching type is easier, non-latching type performs better. either type should work.

Tracking down RFI can be a bit of "black art". While founded upon science, it is most often solved by adding filters till the problem goes away.

Also: make certain that the radio has a solid ground. If there is no "earth ground" at least be sure the the negative wire is well connected to the battery.

-- edit, to add --

Confirm adequate ground on both devices. Make sure that the power leads to the pump are sufficiently large, considering the power need of the pump, as well as the distance from the power source ( battery ).
 
Also: make certain that the radio has a solid ground. If there is no "earth ground" at least be sure the the negative wire is well connected to the battery.

-- edit, to add --

Confirm adequate ground on both devices. Make sure that the power leads to the pump are sufficiently large, considering the power need of the pump, as well as the distance from the power source ( battery ).

As stated most noise comes from bad grounds or audio wiring touching a ground.

One question is the noise only on the radio have you tried a cd or other source?
 
In addition to using #43 Toroids get a .01mfd Ceramic capacitor rated at 150v or higher place it as close to the motor as possible.
Put Toroids on the radio and amps as well.
Obviously turn the power off b4 attempting the capacitor installation.
 
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