RCA flat panel L42FHD37 When first turned on no sound but picture. Hooked through HDMI1 port from dish network satellite. If after turned on go to HDMI2 then back to HDMI1 the sound magically returns...How do I fix? Thanks

Check in the menu of the tv do there is any option to select the input source. If so the select there its to hdmi 1. after that turn off the tv and ON again and check do it go back to TV mode.
If you wish to get some details; check the site linked here. Pull up older posts.
http://electro-medical.blogspot.com/

T'Con board fault. If you wish to get some details; check the site linked here. Viewing it in "Mosaic" or "Magazine" will make surf easy. Pull up older posts. Surf the site with patience. Do a search by type in the brand name of your device at its search box and press "Enter".
http://electronicshelponline.blogspot.com/

Your sound bar should have some sort of HDMI IN and HDMI OUT. This means that there are at least one place to plug a HDMI cable into the bar from either your dish or bluray player and then you take another HDMI cable and plug it into the port labeled HDMI OUT and this will plug into your TV either in HDMI1, HDMI2, or HDMI3 and then it will provide sound for the device. Unfortunately you didn't not list the item so I can not look it up to see if it can accept multiple devices so if it only has two HDMI ports then it can only support one device and you will have to manually change out devices through the HDMI IN port. Essentially the soundbar is just a pass though and takes the sound and sends the picture to the tv.

Reset the receiver by unplugging it for 10 seconds then plug it back in. Unplug the HDMI cable from the TV and the receiver and plug it back in. If you are still not getting any sound connect another component (VCR, DVD Player, etc.) to the same TV, using same cable, same input, and same channel to see if it works. If it still doesn't work with the other component, replace the cable. If it works then give us a call at 1-800-333-DISH (3474) for some additional troubleshooting. We hope this helps. Thank you for being a valued DISH Network customer.

Phillip Chang
DISH Network Customer Service Representative

Tv turn on now,does it have a flashes of pictures only few sec. than dies have sound left only?Yes,than those 2 long boards call the LCD inverter boards are dead.These 2 long LCD inverter boards help the LCD screen panel to have a backlight to produced a picture.Tries websites like Shopjimmy.com,Ebay.com to buy those refurbishes 2 long LCD inverter boards for the replacement.

Unplug the TV wait 10 Seconds and Plug it back in. Should work fine

Sometimess it is the dish receiver have you tried rebooting the dish receiver, hold down the power button on the dish receiver until the picture goes away then turn the button aloose then don't mess with it until the receiver reboots, then see if your audio returns.

First re-check your wire hook up and audio menu settings. If its under warranty then get it replaced if not the repair is an easy fix. Should be sameday return @ your local tv repair center.

Ok. PCB means Printed Circuit Board.
It looks similar to the picture down below. A part must have gone bad on your PC board. So, the RCA shop ordered a replacement PC board to fix the problem. It's an interchangeable part. All newer TV now have PC boards, which each one hold a different function.

you can try changing the assigned channel.you should have to put the second T V on a certain channel like channel 72 or 68 or something like that.on the main reveiver you should go into the menu and poke around in the setting until you see a REMOTE ADDRESS option walk through the steps and change the channel that the second TV receives its picture on, you should shoot for channel 62-72.also make sure the hisense is set to a cable input.you can go into the menu on the hisense and go to your settings and change this .it will be on CABLE or ANTENNA.try switching those around.also did you have sound before coming out of the coax output on the hisense? if your not sure then plug a vcr into and make sure the TV is working with different equipment.GOOD LUCK!