If you have purchased a TBS tuner card and find that Tvheadend recognizes it, but it will not scan muxes that you have entered in Tvheadend, here is one thing to try. Go to the Configuration tab, then the DVB Inputs tab, and then the TV Adapters tab. Find the associated tuner (the one that should be utilized by the mux that won’t scan) in the left-hand list (you might have to expand the entries) – it will probably be listed as something like TurboSight TBS [model number] DVBS/S2 frontend : DVB-S #0 or something similar. Click on that line, and on the right hand side you should see a panel that looks like this:
Note where the red text is – make a note of the original values in those fields (probably 0 in the “Skip Initial Bytes” field, and 18800 in the “Input Buffer (Bytes)” field unless you have changed them for some reason) and temporarily set them both to 0. Click save and then try scanning the mux again. Afterwards, don’t forget to change those fields back to their original values, otherwise you may have issues with recordings or watching Live TV.
I don’t know why some TBS cards (mostly newer ones, I think) need this adjustment in order to scan a mux, and why some (older?) ones do not. All I know is that without this temporary adjustment, Tvheadend is unable to scan a mux with some TBS card models. I don’t know whether a newer version of Tvheadend will fix this problem.
And in case you didn’t know, 0 may not be the optimum value for the “Skip Initial Bytes” field. See the article Getting bad satellite recordings in Tvheadend? Here’s a possible fix for more information.
Also, if you are using Tvheadend 4.2 or later, there are are some new checkboxes in the Add/Edit MUX screens that you need to know about, that you can only see if you are using the “Expert” view level. The screenshot below shows an unconfigured mux, but does show the locations of the new checkboxes. In North America you are probably going to need to check both of these. If you don’t, some or all services on a mux may not scan in, or later on when you attempt to watch a channel on that mux, you may get “No input source available for subscription” errors or other errors.