Re: ms pac voltage trouble

<x-flowed>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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</x-flowed>
Received on Fri Mar 18 10:56:16 2005