Electrical Issues on Shore Power

bobcaller · 03-26-2016, 08:09 AM

We have just purchased a pristine 2007 Itasca Spirit 31C Class C. This is our third motor home. Everything works great on 12 volt, but when I either plug in to shore power or run the generator I get interference bars on the Jensen 12v TV with slight ticking sounds in the surround sound. Also the tank levels work normally on house batteries but show full on AC power (either plugged in or running on generator).
I am showing normal DC voltage output from the converter.

Any ideas? I appreciate the help.

dpinvidic · 03-26-2016, 08:17 AM

Do you know if you have a converter (120v to 12v) or an inverter (12v to 120v)?

Either way it sounds like the 12v side is putting out a lot if ripple. The inverter puts out 12v to charge your batteries when on shore power.

I suspect you have a converter since you bave a 12v TV.

Put your volt meter on the AC range and check 12v for ripple (1 or more volts AC).

Regards

Dan

bobcaller · 03-26-2016, 09:59 AM

I do have a converter, Paralax Series 7300.
I only have a cheap meter, and on the AC scale at a 12v outlet it shows 25.1 volts without shore power or generator. Of course that cannot be accurate, however with the generator running the same outlet shows 26.1, net gain of 1 volt AC.
I am certain that the meter does not have a capacitor for an accurate reading, as posted in this thread: http://www.irv2.com/forums/f54/weird...-283572-2.html.

bobcaller · 03-29-2016, 07:46 PM

Would this be a converter issue, or maybe a ground issue? I really do appreciate the feedback. Just not sure where to start.

grtharris · 03-29-2016, 07:57 PM

bobcaller, check for loose wires around the converter output wiring. A loose wire will put a lot of noise on the +12VDC line.
But could be a noisy output from your converter. They do sell just the converter part for you power control center.

LookAtUSNow · 03-30-2016, 06:46 AM

Since you have a 12 volt tv showing problems, leads me to believe it is a 12 volt issue. In addition to loose wires, check and clean all the do connections? Since your problem seems to be dc related, I'd also check to make sure you don't have a dead cell in one of the batteries, that can reek havoc and is easy to miss. I'd try simple first before I start replacing components.

bobcaller · 03-30-2016, 08:57 PM

Thank you so much for the feedback. I will check the wiring, and have the batteries tested. The puzzle is both the tv and the spiked tank level indicators that both work fine when it is not plugged into shore power.

dpinvidic · 04-04-2016, 07:22 AM

Quote:

Originally Posted by bobcaller

Thank you so much for the feedback. I will check the wiring, and have the batteries tested. The puzzle is both the tv and the spiked tank level indicators that both work fine when it is not plugged into shore power.

I would invest is a better meter ($25 or so).
Just checking for lose wires is not the best trouble shooting method.

You should be able to put you meter in the shore power outlet and measure 117V or so.

Then actauly measure the 12V and the 120V circuits to see what is wrong...it saves a bunch of time.

I believe your converter just acts like a big battery charger and is always connected to the batteries. If that is the case, then the converter is bad.

I don't think the 12V circuit switches from the batteries to the converter with a relay.

A Battery is pure DC, but a cheap or bad converter can add AC ripple on top of the DC. This would explain your symptom of stuff working without shore power.

Regards,

Dan

Sweetbriar · 04-04-2016, 07:55 AM

Quote:

Originally Posted by dpinvidic

,,,A Battery is pure DC, but a cheap or bad converter can add AC ripple on top of the DC. This would explain your symptom of stuff working without shore power.,,,

My first thoughts also. Both the TV and tank indicators are DC powered and sensitive to AC ripple the convertor/charger is inducing when on shore power or with the generator running.

Try this. With the coach on shore power or generator trip the breaker for the convertor and see if the noise goes away and the tank indicators read as expected. I suspect they will which indicates the convertor is the leaking AC. Doesn't take much ripple to cause problems.

nothermark · 04-04-2016, 08:14 AM

You should not be seeing 25 VAC on your 12 VDC line. I would be looking for either a bad battery or a blown rectifier in the converter. How well does your unit work when not plugged in or on generator? If you have very short battery life I would start there.

FWIW by definintion Inverters do not make DC. There are combination inverter/converter units usually with high wattage for whole house inversion that also charge the batteries when acting as a converter.

mel s · 04-04-2016, 08:32 AM

Quote:

Originally Posted by bobcaller

We have just purchased a pristine 2007 Itasca Spirit 31C Class C. This is our third motor home. Everything works great on 12 volt, but when I either plug in to shore power or run the generator I get interference bars on the Jensen 12v TV with slight ticking sounds in the surround sound. Also the tank levels work normally on house batteries but show full on AC power (either plugged in or running on generator).
I am showing normal DC voltage output from the converter.
Any ideas? I appreciate the help.

bobcaller
In some coaches turning on a 12V florescent ceiling light can cause that, (especially if the bulbs or a ballast is failing).
Mel
'96 Safari

bobcaller · 04-12-2016, 05:10 PM

Issue is solved. It was a bad converter, and I replaced it with an upgrade converter from bestconverters. No more lines in tv and tanks are accurate now.
Thanks to all for the help!

By the way, this is my second Winnebago, the first was a 1987 Minnie Winnie 21 foot class C that I owned for 15 years. Two years ago I "upgraded" to a 2003 31 foot Gulfstream Conquest Classic. What a difference in quality! Never again. I sold it and am now happy to be back with the 2007 Itasca 31C!