Electrical impacting Car Stereo

[33fromSD]

I tried everything suggested above with no luck, still crackling / popping / static with the engine running in both AM/FM & Aux components.

After rewiring, if you recall I had a separate ground from the stereo ground to the (-) on the battery, I ran the power to the (+) on the battery so power was totally isolated from the car's wiring harness, I also reran the speaker wires totally separate from the wiring harness (originally I had them coming up the center in parallel to the rear harnesses). I then added a separate ground wire from the stereo chassis to the frame as suggested above and, I also added a separate ground wire from the antenna to the frame as suggested above. So visualize three separate wires for ground, the issue of static, popping & crackling still occurred after all that.

Today, considering nothing else has worked I decided to combine the stereo chassis ground and antenna ground into a single connection to the frame (see pic) as a "what the hell do I have to lose" attempt, and to my shock and utter surprise, IT WORKED!! With the engine running, all the static, popping and crackling is now gone, the radio, and aux components are crystal clear with the engine running.

A ground is a ground is a ground, so can someone who is either an audio expert, or an electrical expert explain to me why combining grounds on the stereo chassis and antenna to a single grounding point on the chassis resolved the issues verses individual separate grounds?

Don't get me, I am more than thrilled that this is resolved and I can now play my stereo after chassing it for several weeks, but I cannot wrap my head around why combining grounds worked verses separate grounds.

fullsizeoutput_63.jpeg

Jim

[jts359]

Back in the day Studebaker Avanti's and Corvette's had ignition shielding around the distributor and spark plug wires , I would think 50 years later that technology would have advanced so one would not have go to such extremes , But maybe not ! Ed

[JimLev]

Most likely you had a ground loop so grounding both the stereo chassis and antenna at the same point eliminated the ground loop.
Looks like I have the same antenna as you.

[33fromSD]

Most likely you had a ground loop so grounding both the stereo chassis and antenna at the same point eliminated the ground loop.
Looks like I have the same antenna as you.

Seems odd to be a ground loop when the stereo chassis and antenna while the ground wires were indeed separate, were tied to the same part of the frame under the dash within 2" of each other. Hard to believe a 2" space on the same frame section created a ground loop?

Jim

[narly1]

Car antenna cables are coaxial, meaning that an insulated center conductor runs insulated (by what we call the dielectric) inside a"tube" (made of braided wire) which we call the shield. Thus the antenna cable should be automatically be grounded when you plug it into the radio chassis. I'm surprised that they also give you a second ground at the plug end. Maybe it's not electrically connected to the connector shell? A simple ohmmeter check would confirm...

[33fromSD]

Car antenna cables are coaxial, meaning that an insulated center conductor runs insulated (by what we call the dielectric) inside a"tube" (made of braided wire) which we call the shield. Thus the antenna cable should be automatically be grounded when you plug it into the radio chassis. I'm surprised that they also give you a second ground at the plug end. Maybe it's not electrically connected to the connector shell? A simple ohmmeter check would confirm...

Hi Early

I actually added the ground wire to the shield that was bent over the outer insulation. Just plugging in the antenna to the stereo chassis mating connector without the ground still resulted in popping, static / crackling.

Jim

[narly1]

LOL "Early" only my wife calls me that, LOL.

Most of the coaxial cable used for car antennas is pretty marginal in terms of the percentage of braid coverage around the inner conductor. I'm still going to stand by my hypothesis though that either the braid is either poorly bonded to the plug shell, the jack shell in the radio itself is not grounded, or maybe even both.

The bottom line is that you figured it it out so good work.

Persistance wears down resistance.

[33fromSD]

[QUOTE] LOL "Early" only my wife calls me that, LOL.

Most of the coaxial cable used for car antennas is pretty marginal in terms of the percentage of braid coverage around the inner conductor. I'm still going to stand by my hypothesis though that either the braid is either poorly bonded to the plug shell, the jack shell in the radio itself is not grounded, or maybe even both.

The bottom line is that you figured it it out so good work.

Persistance wears down resistance. [QUOTE]

Typo ...sorry!!

Jim

[narly1]

It's all good Jim, you made me laugh.

[KGTM]

Do you have power amp or direct from dash player speaker output?

[33fromSD]

Do you have power amp or direct from dash player speaker output?

Direct from stereo in dash's speaker outputs to speaker wires, no power amp.

Jim

[KGTM]

Generally you do not want your antenna grounded to chassis since the coax has its own ground wire back to radio.

Now as why noise, most of the time these grounds are isolated as how is connected on the PCB, and connecting them far from each other will inject the noise difference between the two to internal ground.

At least solved.

Mostafa

[33fromSD]

Generally you do not want your antenna grounded to chassis since the coax has its own ground wire back to radio.

Now as why noise, most of the time these grounds are isolated as how is connected on the PCB, and connecting them far from each other will inject the noise difference between the two to internal ground.

At least solved.

Mostafa

Hey Mostafa

Agree on everything, which is why I was baffled by the resolution, it broke all the rules I knew for car audio.

But, like you noted it's resolved so I'm good.

Jim

[progmgr1]

I was a mechanical engineer who worked in various military and aerospace electronics companies for 40+ years (inertial navigation systems, satellite robotics, RF antenna systems, Li-Ion battery systems, etc.) Electro-Magnetic Interference / Control was a black art that caused us a lot of heartburn / labor / $, but the starting point was "always" to have a single point ground. Everything after that was just magic mixed with trial and error. Glad you found a solution relatively quickly.
Keith HR #894