Hi All, I will start at the begining to help you get an idea of the strange going ons, please bare with me,
I have a thompson freeview anytime box, connected with a analogue aerial, I use a small booster from the socket in the front room, I get most of the freeview channels all with a good solid picture all be it with a hicup once in a while the pic will freeze with sound still there, anyway we wanted a tv in the bedroom so I thought I would split the cable in the loft, thinking that I would get loss I got a 4 room booster with adjustable gain to plug into, I cut the coax and put a f-connector on both ends I screwed aerial side into the receiving port and the tv side into the output, I then screwed the new cable for the bedroom in and connected our second freeview box. NOTHING no signal at all in the setup menu, so I checked downstairs again nothing no signal.. so back into the loft to check connections.. all seem to be o.k hmmm I thought maybe to much gain.. so turned it down to half way... still nothing turn it all the way down still nothing, so took it all apart. used standard end fittings and different booster box, nothing not 1 little bar of signal. so took out the booster and just used a splitter box.. ahhha signal, re-tuned tv in bedroom.. got most channels but lost some of the ones we had before. went dowstairs and checked that one but it was only getting bbc based channels no other service... hmmm strange so back in the loft for a tinker.. all seemed well re-checked end fittings.. so I thought maybe most signal was going to the shorter cable into the bedroom with less going down the longer cable to the front room.. So i now thought i would try the booster again on the out connection to the front room... but as soon as i put that on I lost signal to everything again.. so yep back into the loft take the booster off unplug the splitter and back to basics, just a cable connector to connect the orignal cable together no other tvs or digi box just back to the original set up all be it with a connector inline, so back dowstairs and re-tune... can you believe it... only bbc channels.. what arghhh. so back into the loft.. pull off the ends take off the connector pull back the copper weave sheath on both ends cruedly twist the together get the centre core wire pair of pliers twisted them together.. leave whole thing dangerling and back down stairs.. and guess what.. yep I got all the channels back that I had to start with.. yay... but I am back to square one... still no tv in the bedroom.. phewww sorry about the long read.. but why an what the hell is going on??
I'm guessing your problem is that you are amplifying the signal too much w/ your 1st amp for your 2nd amplifier to handle, and it is just "blowing out". Having too much signal can create amazing problems in all kinds of weird ways
Try eliminating the 1st "small booster" and hook-up your main TV to one of the "4 room booster" outlets.
As always, be real careful about making clean connections.