OT?: failure modes of a RAMDAC

From: Carlos Murillo <cem14_at_cornell.edu>
Date: Tue Jul 4 22:15:58 2000

Tony:

At 06:42 PM 7/4/00 +0100, you wrote:
>Here's a wild guess that you might not have thought of.
>
>What about a fluctuating reference voltage to the RAMDAC? That would
>affect all of R,G,B at the same time. If the reference is external to the
>RAMDAC, maybe it's faulty. Or maybe there's a decoupling capacitor on the
>reference line that's gone leaky and is pulling the line down.

Sounds like a good possibility. Yes, since the failure affects all
colors, it probably originates before any hold/buffer for each color,
and that means either the reference or the summing amp (I assume that
there is a summing amp? it would need to have a very high bandwidth,
though). I'll see if I can make out anything. By the way, today,
the symptoms were present for 5-6 hours and then they went away a few
minutes ago.

carlos.
Received on Tue Jul 04 2000 - 22:15:58 BST

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