*** box F5 - loss of signal

I would make sure you have a coax grounding block on the coax where it comes into the house and ground to a grounding rod or metal cold water pipe.
They make dual grounding blocks for setups with 2 coax cables.The shield on the coax has to be earth ground.

if you have an old pc with serial port as a quickie test you could leave the serial port connected to one of the receivers all the time.This would connect the receiver ground to the pc ground,assuming the pc has a 3 prong power cord.
To me it seems to be a problem with the 2 prong power cord receivers and using 2 receivers in different rooms.(some people don't have a grounding block on the coax,which is part of the electrical code in many areas)

Had this problem on several F5s. they seem to have ultra sensitive tuners in them. Some will fail a blinsd scan on a few requencies, and show "no signal" on some channels. Yet put it on anoter LNB or feed from the same LNB and it works fine. Go figure

in the good old days the receivers had a 3prong power cord,so the coax shield was guaranteed to be at earth ground.With the 2 prong power cord the shield is just floating if you have no grounding blocks.

M8 openboxes suffered from an issue with lnb switching voltage too high and tou would loose cports channels like *** sports 2 and F1 I posted a fix on here for it of you can get it off flea bay its a diode that you put inline which drops the voltage and works a treat. I had it on three open boxes I did for mates and this cured them look here not saying its deffo the problem but easy to check. http://linuxsat-support.com/op…g-channels.html#post49420

that was with just 1 receiver on 1 lnb