TechTools Archives: Re: ms pac voltage trouble

From: tony <tony_at_htbsusa.com>
Date: Fri Mar 18 2005 - 19:56:48 EST

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</head><BODY BGCOLOR="#F0F0F0" >ok kev got it right
at first i replaced all row 6 roms no change then row 5 like kev said and no more garbage
5f and 5e were bad replacing fixed the garbage 
now game plays but i have orange ghost when you eat a power pellet and orange cherries all fruit is orange in corner
and the maze is more orange than pink
midway logo at beginning is blue
i tried to swap out 7f and 4a with one from a pac man board not a ms pack and it made it worse all colors were wrong is a 7f and 4 a different on a pac than a ms pac
what causes this ??? ghost and fruit colors
thanks kev 
ton On Fri, 18 Mar 2005 22:08:48 +0000, martin@guddler.co.uk wrote: >ÊKev, this answers your question i think... > >ÊHonest, in certain circumstances it can (and does) work. It may >Êhelp that i'm not so technically minded just yet so i look at it >Êfrom a more logical point of view. I don't know all the ins and >Êouts of why maybe it didn't ought to work, but from a simplistic >Êpoint of view: > >ÊIf you stick a good chip on top of a good chip you should see no >Êdifference, both chips will do exactly the same (unless maybe they >Êare different speeds or something) and you should see no difference >Êin the game. Granted, do it with the power on, and if it's program >Êram you'll almost definately crash the program. Not sure about >Êvideo ram. Bottom line you shouldn't really do it with the power on >Ê- but surely everyone knows that anyway :) > >ÊIf you put a good chip on top of a bad chip then at the very least >Êi'd expect to see a difference. Yes, if it's program ram it may not >Êsuddenly make the program run since the outputs from the chip could >Êaffect the good one. Seeing a difference warrants further >Êinvestigation in that area, you can be lucky and find it solves it >Êcompletely. > >ÊSo, in the case of the Frogger, i did admittedly have a bit of a >Êhead start. Half the screen was full of rubbish, the other half >Êfine so i knew it was a video fault of some sort. Powered off, put >Êa good ram on top of one of the two 2114s in the video ram, >Êswi
tched back on, perfect screen. Switch off, remove it, crap back >Êagain. > >ÊBingo, fault found. > >ÊSomething i always do with things like galaxians and in this case >Êfrogger simply because it's quick and easy to try befor digging >Êeven a logic probe or meter out. ><SP
AN style="font-size:10pt;"> >ÊGoing back to the original post, i don't know if it will help or >Ênot since i don't remember what the original problem was (and am >Êrecompiling my OS so have no email history), my point was merely if >Êit appears to be a graphics issue, give it a try it'll take no >Êtime. Just be careful not to short anything out or other. > >ÊSomething that works for me and now i'll shut up
since i've waffled >Êon far too much already :) YMMV > >ÊRegards, >ÊMartin. > >ÊJohn Robertson <jrr@flippers.com>Êwrote: > >>ÊI will have to try that sometime, can't hurt! &gt
;> >>ÊStill it might surprise me to see it works, but perhaps if it is >>Êa bad (open) output on the RAM then your idea would certainly >>Êwork even with static RAM like 2114's. >> >>ÊJohn :-#)# >> >>ÊAt 6:47 PM +0000 3/18/05, martin@guddler.co.uk wrote: >>>ÊWell, it's certainly far from foolproof, but it takes no time >>>Êat all to quickly do and if your problem is completely solved >>>Êwhen piggybacking a >>> >>Êsingle >>>ÊIC then it was worth it :) >>> >>>ÊI often find it helpful with logic chips too but that is >>>Êdefinately not foolproof, the bad chip often still affecting >>>Êthe inputs and outputs of the good chip. Again, it's quick and >>>Êit sometimes get's me quick results >>> >Êthough. > >>>ÊMartin. >>> >>>ÊJohn Robertson <jrr@flippers.com>Êwrote: >>> >>>>ÊGenerally speaking that only works with Dynamic RAM that has >>>>Êfloating outputs. I'm surprised it works with 2114s, however >>>>Êit should work with the Video RAM on the Pacman/Ms Pacman >>>>Êboards. >>>> >>&gt
;>ÊJohn :-#)# >>>> >>>>ÊAt 12:26 PM -0500 3/18/05, Electronicamuse@aol.com wrote: >>>> >>>>>ÊIn a message dated 3/18/2005 8:47:19 A.M. Eastern Standard >>>>>ÊTime, martin@guddler.co.uk writes: >>>>> >>>>>ÊMore times than not i find piggybacking each of the 2114's >>>>>Êin turn with a known good one will reveal which one(s) it is >>>>> >>>>>ÊDo other folks concur that this can be done? ÊI am not >>>>>Êlooking for 100$ accuracy, but any fast tips can be of help. >>>>> >>>>>ÊThanks >>>>> >>>&g
t;>ÊDave >>>>> >> >>Ê_______________________________________________ >>ÊTechtoolslist mailing list >>ÊTechtoolslist@flippers.com >>Êhttp://seven.pairlist.net/mailman/listinfo/techtoolslist > > >Ê_______________________________________________ >ÊTechtoolslist mailing list >ÊTechtoolslist@flippers.com >Êhttp://seven.pairlist.net/mailman/listinfo/techtoolslist 
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Received on Fri Mar 18 17:06:11 2005

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