On Sat, 29 May 2010 15:15:36 +0200, "Caius" wrote:


ha scritto nel messaggio
...
On May 27, 8:49 am,
You cannot make that assumption without a scope which unfortunately
you don't have. I'm only guessing but I bet your video has bad low
frequency tilt which shows of as the 'DC' of the back porch wandering
all over the place. Cause: bad capacitors somewhere in the video
chain. IIRC the Gennum chip includes clamps to guarantee sampling at
50% of the sync pulse meaning it's more tolerant of poor video. The
scope would tell all.

G²

Ok, thanks.Sadly the video (R,G,B ground + SYNC) is from arcade videogame
pcb, so I assume they have all poor video signal???
I 'd wan to try the Gennum GS4981 but it seems unfindable...

?? have you tried their website? Google "gennum gs4981" and first
hit. Then go to the "buy from distributor" or "get free sample"
(sounds better) link at
http://www.gennum.com/buy/sales-network