OT?: failure modes of a RAMDAC

From: jpero_at_sympatico.ca <(jpero_at_sympatico.ca)>
Date: Tue Jul 4 18:56:27 2000

> Date: Tue, 04 Jul 2000 23:15:58 -0400
> From: Carlos Murillo <cem14_at_cornell.edu>
> Subject: Re: OT?: failure modes of a RAMDAC
> To: classiccmp_at_classiccmp.org
> Reply-to: classiccmp_at_classiccmp.org

> Tony:


> 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.


Do you have electronics tools and a very strong magnifying glass?

Look carefully on the RAMDAC pins especially power pins for solder
quality. Measure for voltages and monitor it with oscilloscope for
ripples on both -.3.3V (A10) regulator and the little 8pin SMD
regulator IC, this little one feeds directly to RAMDAC; (LM87L05ACM
pin 1 at A2) (!!).

First try these two things before pulling out the shotgun;
Can't hurt to brush off the dust too and polish the PCI contacts on
that millennium video card with piece of torn off paper.

How did I know? That right, I've have one for bench testing
motherboards and I have seen another one that come up blank and no
beeps due to dirt 'n dust on chips and PCI contacts on that card

Matrox cards very nice and speedy, IMHO.


> carlos.
Received on Tue Jul 04 2000 - 18:56:27 BST

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