Turbo Express Video Out Mod

From <xxxxxx@rogers.com>
Date
Dear TG and PCE'ers,

At present on ebay I have found an auction for a PC Engine GT with TV 
OUT where the Turbo Vision would normally go. 
I'm wondering, how hard would it be to hijack the signal going to the 
LCD and send it out the turbo vision port?  I know for certain that 
said port is connected internally to the PCB via a ribbon cable. 
More precisely, I guess, is there an online reference to a tg express 
schematic?  I could certainly use one not only for this hack but also 
for my volume level troubles. 
-Alex

1