Jason I did call Lowrance and they told me they did not make that part any longer or any part for units that old and I needed to check e-bay. He said I might find a used one there. The guy I talked to on the phone needs to take a class on how to talk to customers on the phone. That makes the company look bad the way he spoke to me. He sounded like I had old out of date products and needed to up date what I had. If that is the way they take care of customers who spent a lot of $$$$$$$$$$$$$ with them why would I want to spend more.
You have been very helpful with me and I did find a cable, now just to hook it up and see if it is/was the problem. Now I know what to look for I may be able to find it under the dash. Could be a loose ground of blown fuse... Fingers crossed for a simple fix.
Thanks for your help...
Tommy

I am with UJC. I had the same problem. Previous owner had the red and yellow run opposite from the preferred method. It will work that way but just not how the diagram shows it. I got the same "No Source" message. Described problem to Lowrance tech and he was convinced that it was the box. So I order a new box. In the meantime I start reading about Ethernet cables so I decided to just try the new cable. Sure enough it was just the cable. I got a great price on the box so it was easy to sell.

Yea I found it... Ground wire had come loose under the dash... wire was out of one of those push on a tabs. It was in the collar and when I wiggled the wire it popped out. Took a while to find and about 10 minutes to fix.