Depth sounder interference through stereo

[SomeFloridaGuy]

Hi all -- I'm new here, and here's my problem:<br /><br />I have a Proline 22' CC with a Garmin GPSmap 168 Sounder (combination GPS and depth sounder.) Whenever the Garmin unit is powered on, I hear a popping sound through my stereo speakers. The source of the interference is definitely the depth sounder -- when I turn the depth sounder off the sound goes away.<br /><br />The stereo is an Eclipse head unit with a JBL amp. It was professionally installed, but the installers are stumped by the interference (they've tried rerouting cables, and replaced the RCA cables from the head unit to the amp with the "ultra-shielded" type of cables).<br /><br />Thanks in advance for any tips!<br />CS

 

[snapperbait]

Re: Depth sounder interference through stereo

If the either the postive or negative sides of both the radio ,and amp, and the fishfinder all share a common connection like a negative terminal bus, then there's a fair posibility that you may get some noise...

 

[18rabbit]

Re: Depth sounder interference through stereo

Welcome to the board, FloridaGuy!!! <br /><br />Three things come to mind. 1) Pwr/grn exactly as snapperbait mentioned 2) breaks, cuts or splices in the transducer cable that are in proximity of the stereo including resistance in the cable-to-head connection, and 3) an internally damaged transducer. Start with snapperbait’s suggestion. His advice is always good. <br /><br />To eliminate the transducer and/or its cable as the source of the problem, you can borrow a transducer, connect it to the Garmin head, suspend the ‘ducer in a bucket of water and let her rip.

 

[Boilermaker]

Re: Depth sounder interference through stereo

Sounds like your getting a pulse on the 12VDC line. Try putting a FERRITE CHOKE on the D.C. lines of the amp & sterio. This should get rid of a pulse or A.C. that may be riding on the D.C. lines. The "PRO INSTALLERS" should have them, or you could try a RADIOSHACK noise kit for car sterios.

 

[SomeFloridaGuy]

Re: Depth sounder interference through stereo

Wow, thanks for all the replies (and for the warm welcome!)<br /><br />As far as common connections, here's the deal: The amp is wired directly to one of the batteries, with some large gauge cables (and a fuse close to the battery )<br /><br />The stereo head unit is wired to one of the spare accessory circuits/switches on the console.<br /><br />Not sure what circuit the Garmin unit is wired into (it was installed by the Proline dealer, along with a JRC VHF, before delivery.) The boat is only seven months old, and I've only gotten 16 hours on it so far!<br /><br />I'll check (as best I can!) the things suggested above. One thing that concerns me is that the amp's power and ground cables are routed through the same parts of the hull (to get to the batteries, which are near the transom) as the transducer cable (which is transom-mounted.) This routing path is pretty inaccessible (I'm not even sure how the stereo guy fished the power and ground cables through there in the first place!)<br /><br />I'll also try a couple of ferrite chokes, as recommended. (When mounting a choke on a power cable, should it be placed near the end of the cable close to the power source or near the end close to the unit, or does it matter?)<br /><br />Thanks again all, and I'll report back after I try the suggestions.<br /><br />Happy boating,<br />CS

 

[snapperbait]

Re: Depth sounder interference through stereo

Say, FloridaGuy... Whats your lo-cal?..<br /><br />

Start with snapperbait’s suggestion. His advice is always good.

Rabbit.. Yer a trip... That kind of flattery is'nt going to get you one of the prized and highly sought after "seceret decoder rings" you so desperately deisre... Sorry... Good try buddy...

 

[rickdb1boat]

Re: Depth sounder interference through stereo

snapperbait <br /><br />You are dead on, no matter how it comes about. You more than likely will have interference if you run either wire in conjuction. So easy to separate, so why not do it right. Just fact, although flattery may be intended. Please send seceret decoder rings as soon as possible..

 

[SomeFloridaGuy]

Re: Depth sounder interference through stereo

Say, FloridaGuy... Whats your lo-cal?..

Snapperbait: I live in Westchase, which is a suburb of Tampa in the northwest part of Hillsborough County. The boat is stored at the Tierra Verde Marina High and Dry (in St. Petersburg). I see you're in West Palm Beach? Nice area!