I have finally got my box connected, but it is saying the TV signal is weak or lost. the tv works fine on its own

The TV can do many things
name 1 thing you can't do
is this a cable box, input dead
or HD TV antenna dead.
or dead wifi to web
or dead ethernet to web
dead net flix,
tell what you want to watch, that would be a nice start

Sounds that you have to use a signal booster. Contact any service technician. http://electronicshelponline.blogspot.com/

try swicth cable box for testing....if sam problem..need replaced tv main board

Had the same problem.
Fixed by unplugging everything from the power source, leaving for 2 minutes then plugging back in.
Works fine now.

There is some sort of setting you need to change on the JVC receiver. I had this same problem, and I read the manual and it solved it. You need to press and hold down a button to change the mode. Your unit probably says "TV Sound" right now. Once you press this button (not sure what button) like the manual says, the display should change to "DBS" and then it should work just fne.

Here are a few suggestions,

*Check your connections to make sure none are loose.

*Try checking the Dish box to make sure everything that should be turned on is actually on.

*Also make sure channel 3 is the correct channel by contacting your service provider.

I hope theis solution is helpful. Please take a moment to rate this solution.

Mine did the same thing once. I think all I did was hit the setup on the remote, and let it run back through all the channels and then it worked just fine.

I hope this works for you.

1. Since my problem (Samsung/Comcast) began with a channel selection button pushed on the TV remote when it should have been pushed on the cable remote, I figured the problem lay with the TV.  Although I was getting the "weak or no signal" msg., the actual signal strength bar graphic showed it to be strong. Disconnecting did no good. I surmised that the TV was simply not recognizing the box.
2. I looked at the manual for my Samsung 750 model. 
3. Page 20 discussed "Selecting the source". I accessed the TV menu and selected "Input", then chose the "HD..." item from the highlighted list. Voila! My tv works again. 

Hey! I have the same problem as you. But! this would happen only when I got a power outage. Unplug the TV for a couple of minutesand all was fine. For the last 5 day I have no TV. I have tried everything. All the out on the TV and I still get unusable signal. My rep told me to unplug for 24 Hours. Still didn't work. My menu option work as well and every time I put the TV on, off or if I change the input sound will come on for 2 seconde and stop. If I find the salution I will let you know. Gilles Ottawa