Am I missing something here? John is talking about video RAM. By that I would assume he is NOT talking about 2114s (which would mostly be caught during self test) but the line buffer RAM in the 2A to 2D locations. tony wrote:
is there a way to test the 2114 ram on the board or do i have to pull all of them and test in
my mod-a tester
thanks Tony
On Thu, 17 Mar 2005 21:10:23 -0800, John Robertson wrote:
If the board produces a good image when you increase the 5VDC supply then your video RAM has at least one bad IC. RAM is usually the most susceptible to voltage fluctuations and will show errors faster than other parts.
Also the fact that the game runs indicates it is not on the Data bus, rather it is the video handling circuits...
John :-#)#
At 9:53 PM -0500 3/17/05, tony wrote:
i am working a a ms pac man with a daughter board all ac voltages
are fine sound works great its 5 volt line is at 4.95 vdc at c2 and
c3 and the game plays but the graphics are real bad and lines
through the picture, the d7 un banded to d8 ubd 13.5 vac and d3
to d4 ubd 25.5 vac i pulled it from the game and hooked it up on
the bench to a good monitor and my dc power supply though pin 18
and ground and gave it 4.95 volts same thing then i turned it up to
5.75 vdc and bam it all came in fine looks great so how do i get
the ac in the game up or the dc on the board up checked for ac in
the dc and there is none and checked d9 for a short or leaky and it
was not any help
thanks ton
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