[mythtv-users] Load detection on composite video out

Yan Seiner yan at seiner.com
Sun Oct 4 15:50:26 UTC 2009

I've been struggling with getting my mobo going using the composite 
out.  The bios apparently uses load detection on the port to determine 
if something is hooked up to it or not.

If I hook up a TV, it works fine.  If I hook up my amplified video 
splitter, it fails to detect anything.  So based on a guess that load 
detection is based on current draw, I took my ohmmeter and metered the 
TV and the amp.  The TV meters to about 75 ohms, which at 1V gives me 13 
ma. The amp meters to 22K ohms, which gives me 0.05 ma, probably not 
enough to trigger the load detection circuitry.  (I know this is grossly 
simplifying things, as the load is not purely resistive.  But it's the 
best I can do.)

So.... Can I just add a resistor in parallel, something like 100 or 75 
ohm, to the splitter amp across the input?  I just want to bump up the 
current draw so that the mobo will detect the thing and turn on the 
output at boot.



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