I posted pictures of the connections here:
Tablets and phones that work well with DJI GO
Be sure to get the 'exact' $10 converter from Amazon that I posted about in this thread (a few posts before the above referenced post) as it has been reported that others that seem to be the same (but aren't) will require a USB power, while the one I used is self powered.
It's simply using HDMI source from your table or whatever, which is connected to the converter via the proper HDMI cable, then using an RCA to RCA cable ... you go from the converter's 'video out' to the Quanum DIY goggles' 'video in' (which as you know, also needs a 12V supply) ... I'm using a small LiPo battery for that.
The only issue I'm having with the DIY Quanums is because I'm farsighted, and it's a bit of a challenge to find a set of reading glasses/lens from a magnifying headsets (like jewelers use) to get focus in the Quanums.
But for people using any version of the Quanums FPV goggles successfully, this setup is less cost than the just DJI HDMI controller back, and that includes the price of the $88 10" Proscan tablet (which includes the HDMI output) and the converter.