How to troubleshoot Jensen entertainment unit in rear of cabin
I've recently purchased a 2010 Winn Era 170X. It has a pretty impressive (for its age) Jensen console in the back section, with various speaker sets A, B, and C. Unfortunately, I can only get it to play to speaker set A (the forward-most pair). No response at all from B and C.
Thing is, all the speakers do work, when I play from the dashboard radio. (They're not very good speakers, but that's another matter.) So I know the speakers work.
I'm wondering how to troubleshoot the feed from the cabin console. My first thought is to check the connections. But I cannot see how to pull out any of the components. (Or even the switch that flips between Radio and TV, which really means Dash Radio and Cabin Console.) Everything is mounted on a wood panel, with no obvious way to remove them, or get behind them to check wires. Can anyone offer a suggestion on how to do this?
Possibly those channels are just dead in the unit, but I'd like to rule out other possibilities before I give up on it.