A/V system stutters when using 12V appliances

[tinkerreknit]

My radio/CD/DVD unit is an aftermarket add-on. It works fine until the water pump is in use or when certain lights are turned on (no matter if I am plugged into shore power or not). At that point, the sound will jump and stutter as though there is not ample power. It is extremely irritating! I have the power and ground wires tapped into 12 gauge wires that supply the dining table lights. All connections are solid and clean. What could I do to eliminate this problem? The A/V unit is near the batteries and pretty far away from the power center.

["007"]

If you have florescent lights they have inverters built in that can cause interference with radio's also wire on same 12v circuit as lights may cause problem.
Hook up temp to your chassis battery or house battery and see if that helps.

[tinkerreknit]

Thanks for the advice. I have no fluorescents in the RV. In the next several days I will try a heftier connection to the battery. The largest wire I see in local automotive stores is 12 ga. Is this sufficient, or should I get bigger wire? Can I run the + straight to the battery terminal and the - to a chassis ground? The media center has a built-in fuse.

[Gary RVRoamer]

12 gauge should be plenty for a stereo system. Yes, try the + straight to battery + (with a fuse) and the - to any good ground or battery negative. If that eliminates your stuttering problem, you know it was rippling voltages in the power line that was doing it.

You should be able to get a 12v power filter at places like Radio Shack or an audio equipment shop. Or ebay. They aren't expensive.

[Ray,IN]

This CarPC - Everything you need for your CarPC
will help you with selecting the proper wire size.

[davecampbell]

Have to determine whether its electrical noise or low voltage. Buy a digital voltmeter and check for voltage dropping at the AV equipment when the offending loads are turned on. The pump will make noise on the lines, incandescent lights will not, unless there is a bad eletrical connection somewhere, the voltage should not drop.

Household electronics are not filtered inside against noises in automobiles as is equipment intended for automotive use. Household electronics are more filtered to prevent noise from going out than coming in. If its on the 110 V, and the problem is noise, a brute force solution is to convert, then invert. Wastes power, but itll chop the noise up. 110 to converter, converter out to an inverter. Itll look funny, but wil work.

If its 12V, a 12 V automotive noise filter that filters both positive and negative lines might work. Just make sure in either case there arent any hidden ground paths like TV antennas where noise can sneak in un-filtered.

If its voltage drop, find the bad connection before it gets hot!

[tinkerreknit]

Quote:

Originally Posted by Gary RVRoamer 12 gauge should be plenty for a stereo system. Yes, try the + straight to battery + (with a fuse) and the - to any good ground or battery negative. If that eliminates your stuttering problem, you know it was rippling voltages in the power line that was doing it. You should be able to get a 12v power filter at places like Radio Shack or an audio equipment shop. Or ebay. They aren't expensive.

Thanks Gary,
The calculator was helpful. If I run 8' of 10ga. wire, I will have only 11.754 volts. This is probably OK but I am not sure yet. I did find a hot wire connection just inside the RV and about 4' from the batteries. Using that, the other lights and appliances don't affect the media center nearly as much - even with temporary connections. It is still very cold here so I haven't gotten back to the project yet.

[tinkerreknit]

Quote:

Originally Posted by davecampbell Have to determine whether its electrical noise or low voltage. Buy a digital voltmeter and check for voltage dropping at the AV equipment when the offending loads are turned on. The pump will make noise on the lines, incandescent lights will not, unless there is a bad eletrical connection somewhere, the voltage should not drop. Household electronics are not filtered inside against noises in automobiles as is equipment intended for automotive use. Household electronics are more filtered to prevent noise from going out than coming in. If its on the 110 V, and the problem is noise, a brute force solution is to convert, then invert. Wastes power, but itll chop the noise up. 110 to converter, converter out to an inverter. Itll look funny, but wil work. If its 12V, a 12 V automotive noise filter that filters both positive and negative lines might work. Just make sure in either case there arent any hidden ground paths like TV antennas where noise can sneak in un-filtered. If its voltage drop, find the bad connection before it gets hot!

Thanks davecampbell,
The voltage does indeed drop quite a bit when lights, etc. are switched on. I don't think I am experiencing noise, but rather the media unit is "starved" for power when something else is demanding power. When I turn on a nearby light, the radio will become silent for a few seconds and then pick up again. After I get the power requirements satisfied, I will post back here and then see if I need to address a noise problem. As I posted above, it is extremely cold here lately and I have also been too busy to tackle the wiring. I hope Christmas week will allow me some time to experiment more.

[tinkerreknit]

I ran new wires to a junction a couple of feet from the battery and my problem is solved. Thanks to everyone for the support. I did have a rather unusual problem in that I had a hot wire to one battery and a ground wire to the other battery. It was a problem resulting from the color-coding of the original wiring being altered. The radio would come on but wouldn't play.
Now, can anyone recommend a monitor to install with this unit? I need a 12V monitor with speakers built in - 17" (more or less).

[davecampbell]

Try MCM Electronics: Home and Pro Audio/Video, Security and Test Equipment, occasionally they have decent sales

[Richard Wold]

If you have a master disconnect switch near the front door, you may have a bad disconnect relay. I had similar issues with lights dimming and the electric toilet flush motor running slowly. Problem was the disconnect relay was dropping almost 2 volts under load. Bypassed the relay and I can have every light in the coach on and still get full power.