grrrrr .. alternator whine and system noise [Archive] - JKowners.com : Jeep Wrangler JK Forum

: grrrrr .. alternator whine and system noise


usmcdoc14
04-10-2009, 10:22 AM
HELP.
Installed a dual battery system with hellroaring isolator combiner in the jeep JK. its rear mounted with a 2/0 wire running up to a distribution block. block goes to all pre-existing main power. Bats are ground to body and frame with 2/0. (figured that problem from yesterday)
New head unit, amps and speakers, all wired right, power wires WELL away from RCA.

FAWKING ALTERNATOR HUM :mad: not only that but another constant faint "tweeedleetweeedleeetweedleee" that is not varied with engine RPM.
it stops ONLY when no rca's are in the amps. a Ipod plugged directly into the amp does not do it (so not the amp)

Tried solutions:
Ground amps direct to bat.
gain turned down.
rca direct from head unit to amps in mid air.
head unit direct power and ground from bat.
disconnect hellroaring isolator.
run head unit on an ENTIRELY SEPARATED power supply.
combination of all of the above.

what the ****.

is my alternator bleeding that much ****ing RF that the headunit picks it up even when on an isolated power supply?
solutions?
other things to try?

paragon
04-10-2009, 10:42 AM
ground the amps/radio to a separate, unused ground and not the batt and see if that works

usmcdoc14
04-10-2009, 10:45 AM
ground the amps/radio to a separate, unused ground and not the batt and see if that works

tried.

does the computer throw that much RF in the JK's?

paragon
04-10-2009, 11:05 AM
tried.

does the computer throw that much RF in the JK's?

honestly, it's the first I've heard of it that bad

is there any point where the power from the alt going to the isolator is near amp or radio cables?

I wonder if it could be some RF flowing down the jeep (you did say it was in the back) and interfering with your amp down the wire somewhere

usmcdoc14
04-10-2009, 01:06 PM
honestly, it's the first I've heard of it that bad

is there any point where the power from the alt going to the isolator is near amp or radio cables?

I wonder if it could be some RF flowing down the jeep (you did say it was in the back) and interfering with your amp down the wire somewhere


main power wire goes from distribution block under hood to the passenger frame rail top and all the way to the trunk area, it then goes to the main bat and the isolator is connected to (mind you the hellroaring unit has already been ruled out as a culprit) the amps are mounted on the rollcage ABOVE the rear passenger area. The power for the amps comes up the left rear cage tube to the amps. the ground comes from the front on the left (same side). The RCA's (all of them) come from the front right side (complete opposite of the power) there path is head unit - behind dash above glove box- down right side kick panel- right side rocker- up right side "B" pillar- across cage top to the amps.

paragon
04-10-2009, 01:13 PM
have you unplugged the amp inputs to see if it's at the amps or up stream?

dsy
04-10-2009, 09:26 PM
main power wire goes from distribution block under hood to the passenger frame rail top and all the way to the trunk area, it then goes to the main bat and the isolator is connected to (mind you the hellroaring unit has already been ruled out as a culprit) the amps are mounted on the rollcage ABOVE the rear passenger area. The power for the amps comes up the left rear cage tube to the amps. the ground comes from the front on the left (same side). The RCA's (all of them) come from the front right side (complete opposite of the power) there path is head unit - behind dash above glove box- down right side kick panel- right side rocker- up right side "B" pillar- across cage top to the amps.

Not sure if it would matter or not but are the amps powered from the aux batt and the head unit from the main batt? If so you may want to try running a temp feed to the amps from the main batt just to rule it out.

ksjeep
04-11-2009, 04:14 AM
Just a guess... Pioneer head unit? Wrap a ground wire around the rcas on the head unit... tie it to the nearest screw on the head unit.

Broncojohn
04-11-2009, 05:30 AM
Grounds should be as short as possible, try grounding straight to the rollbar. If your worried about current and don't have access to a megger, to check the rollbar grounding, put a ground strap from the bar to the chassis. RF usually enters through wire so rid yourself from as much length as possible. If its comming through the positive try putting a large (smaller number) capacitor on the positive, it will drain any noise off the power and will help with power spikes and "turn on pop". Then try double shielded RCA cables; it's going to be hard to keep noise off the IPOD connector because the IPOD isn't grounded to the same source as the other equipment so don't skimp on the cable. Do not coil any of audio wiring, lay any excess in a S- pattern under the carpet, and dont pinch or make sharp bends in the line level wiring, it shortens the dielectric gap which protects the signal.

usmcdoc14
04-11-2009, 12:48 PM
Not sure if it would matter or not but are the amps powered from the aux batt and the head unit from the main batt? If so you may want to try running a temp feed to the amps from the main batt just to rule it out.

They are powered off the main bat. the aux is just that and isolated from the system unless I switch it on.

Grounds should be as short as possible, try grounding straight to the rollbar.

It is and they are. max ground wire length is 12" I will post pics later.

If your worried about current and don't have access to a megger, to check the rollbar grounding, put a ground strap from the bar to the chassis.

already did

it's going to be hard to keep noise off the IPOD connector because the IPOD isn't grounded to the same source as the other equipment so don't skimp on the cable.

I did the same with the head unit as I posted above. I wired the HU to its own battery isolated from the vehicles system and it still had hum.

Do not coil any of audio wiring, lay any excess in a S- pattern under the carpet, and dont pinch or make sharp bends in the line level wiring, it shortens the dielectric gap which protects the signal.

Thanks, I am not that much of a noob :thefinger::laughing:

07BlkSahara
04-13-2009, 12:48 PM
What head unit is in it? Pioneer's newer double din head units have had known noise issues for a couple of years now. I don't remember the details but something about powering it up and not connecting the RCA does something strange and blows a ground trace causing noise (or something like that).

Fixed an install two years ago in a brand new Escalade that had all JL and a Pioneer double din. Grounded the head unit and the RCA's with the amps and it fixed it. The radio was grounded with the factory ground in the dash and it was noisy.

usmcdoc14
04-14-2009, 09:02 AM
Its a kenwood dnx7120.
I went to the Kenwood service place for the east and the dude there told me the install is fine and I am being anal retentive :laughing: and that he could hear the noise as well but he would say "fawk it" at this point as well.
I got rid of like 95% of any outside noise, "you" can't hear it unless I crank the gain on the headunit. Its the JK causing RF and there is not much to stop any more of it.