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ADV7604 output sync goes bad after video re-connect

Question asked by fatdave on Dec 5, 2011
Latest reply on Dec 13, 2011 by fatdave

I have inhereted an issue on a video system employing an ADV7604 so I'm not terribly familiar with the chip.  The issue I am seeing is that when feeding the chip digital DVI 1280x1024 @ 60Hz I can get video through the system just fine but frequently I can't get a good sync if I disconnect the input video and then reconnect it.  Instead of a thin sync pulse at 60Hz, I get double pulses about 2ms wide and more than 2.5ms apart that repeat every 43ms.  I'm not sure what is causing it.  As far as I can tell there aren't any modifications made to the registers from the time there is valid video output until the time that the sync signal gets in this more.  Should I be doing something when I detect the loss of input video?  There are, however, changes within the status registers and such.  I have included a register dump of the IO, CP and HDMI registers for the valid operation mode which also indicates where register values change when the sync goes bad.  Also when the sync is not work properly cycling power to the system rights everything and video passes through just fine.  Any ideas?