I have the same unit, or very similar. There is no headphone jack. I pulled the unit out to look at how it's wired. There are speaker outputs on the back of the unit. I used
an Adjustable Line Output Converter. I pulled the RCA inputs that come from where the TV is and connected them to the output converter. Then connected the wires from one set of the speaker outputs to the converter. That reroutes the sound to go out and back to the TV. Simply connect the RCA connectors to the Audio In jacks on the TV, set the speakers on the Jensen to A, B, or C depending on which output wires you use, then use the headphone jack on the TV.
A couple of years ago we bought a refurb Blueray player and put the whole thing back to the factory setup to use the speakers in the trailer.
Chuck D.
โAdventure is just bad planning.โ - Roald Amundsen
2013 Jayco X20E Hybrid
2016 Chevy Silverado Crew Cab Z71 LTZ2
2008 GMC Sierra SLE1 Crew Cab Z71 (traded)