Problem running T.V.

jhaggerty · July 19, 2010, 10:01:14 AM

I have installed a flip down tv monitor in an MC9. It runs on 12 v and works well except when I have OTR air running. As soon as I turn on the air, The screen goes black. I am assuming the voltage drops or is it simething else, amps, etc. The bus alternator is charging at over 28.5 volts . I can't figure it out and this time of year, you need A.C. I do not have any roof top A.C. and no generator. If anybody has any ideas as to the problem I would appreciate hearing. Thanks

Jim

Sean · July 19, 2010, 10:46:24 AM

Where are you taking the 12 volts to run the TV?

-Sean
http://OurOdyssey.BlogSpot.com

gumpy · July 19, 2010, 01:34:09 PM

Did you try putting a volt meter on the tv power cord to see what it is getting before and after you turn on the A/C?

jhaggerty · July 19, 2010, 02:34:30 PM

I am taking 12 volts off the start batteries. No I haven't checked the voltage on the line to the tv. Just got it ready to go yesterday.

Jim

James77MCI8 · July 19, 2010, 05:02:48 PM

When the AC turns on there is a considerable load on the batteries, If you are center tapping the batteries you will be getting half the voltage of the drop when the AC kicks in. The digital TV probably doesn;t like that.

Sean · July 19, 2010, 08:20:30 PM

Quote from: jhaggerty on July 19, 2010, 02:34:30 PM
I am taking 12 volts off the start batteries. No I haven't checked the voltage on the line to the tv. Just got it ready to go yesterday.

Next step will be to measure the voltage. Also, what other 12-volt loads do you have on the center tap of the start batteries, and do you have an equalizer?

If you have an honest 28+ volts going to the batteries with the A/C running, and the TV is the only 12-volt load, then you might have an issue with the lower battery. I would let them charge up on the alternator, then shut down, disconnect them, and measure them individually. You could also check the specific gravity of each cell.

The start batteries are a long way from the driver seat. What gauge wire did you use to bring the 12 volts up?

-Sean
http://OurOdyssey.BlogSpot.com

WEC4104 · July 19, 2010, 08:24:18 PM

I understand that, if the TV is on when you turn on the AC, it kills the TV. ....and like many electronics these days, it will stay off, even if power is restored. What would happen if you tried turning on the TV after the AC has been turned on and the compressor had kicked in? I'm not suggesting this as a solution, just as a test to pinpoint your problem closer.

bevans6 · July 20, 2010, 05:49:19 AM

I bet it's the voltage disruption from the start load and the CEMF ramping up from the big condenser and evaporator fan motors turning on that is kicking off a protection circuit inside the TV. I bet for a few milliseconds there the DC is pretty disrupted. I would try running the TV on an inverter that went from 12 volt to 120AC (presuming it has that option), the electronics in the little inverter may smooth out the power fluctuation.

Brian

jhaggerty · July 20, 2010, 05:48:49 PM

I may have found the problem. Located a loose ground and tightened it up. TV now works alright with AC going. At least here in the yard. Will know better this weekend as we will be on a three day run. Thanks for your input and I will keep all suggestions in mind , just in case the problem isn't solved.

Jim