Ram in pcb video daytona usa - model2

PaTrYcK

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Hi, someone know which are the ram chips in pcb video of sega daytona usa?
Thanks!

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You can find the manuals on SEGA's web page.
Click on the Archives, then the game, and the manual PDF will be on the game page.

Here is a link for Daytona USA 2
http://www.segaarcade.com/sites/default/files/daytona_usa_2_dlx_manual.pdf

The last three pages of the manuals have wiring diagrams which include some chip numbers.

Otherwise, you can start entering the chip numbers on the board, and see which ones come back as memory.
 
Ok, i found chips ram, Toshiba TC518128BFL-80, graphical errors on model2 are often caused to failure of these ram chips

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Yep, that looks like them. I'd suggest finding a source. I looked, and Digikey doesn't appear to stock them. Mouser didn't either. Parts.nowcomponents.com did list them as available, but you have to Request a Quote.

Use the pinouts (available online) to figure out which one or ones are bad. It's unlikely they all went bad (unless there was some horrific event).

You can use a logic probe to make sure the outputs are pulsing properly.

Then again, if you send them to the www.irepairsega.com guy, you can eliminate the hassle to trying to unmake and remake surface mount connections.
 
Hi, thanks for your answer, i usually test all IC before change it, but not is easy test the ram...
Also i found chip ram on ebay, the price not is very expensive, 3usd for each, i think that i will buy 6 new ram
 
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You can remove SMT very easily using a product called ChipQuik - I think Frys still sells the stuff - stays molten at 90 degrees, apply as a bead to all pins, move the soldering iron around all pins, then move the chip off the pads. Clean the pads, place new IC, and solder.
 
Hi, just found this post, am interested to confirm what symptoms your board set was experiencing prior to fixing it.

Did you have any RAM errors in the IC tests or just bad 3D GFX ?

If you can provide any other tips on your testing procedure etc that would be great also.

Thanks in advance
 
Did you have any RAM errors in the IC tests
Hi, ic test not check ram in pcb video

or just bad 3D GFX ?
exactly!

If you can provide any other tips on your testing procedure etc that would be great also.
I talked with sega assistence in my country (italy), they say me that 99% of bad 3dgfx are caused by faulty ram (poor quality)...
I buy ram here:
http://www.ebay.it/itm/110887904338?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649
 
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Hi guys,

Apologies for resurrecting an old thread here, but I too have a Sega Rally board with 3d GFX errors that I am going to attempt to repair by replacing all 6 RAM chips. I can bring the board into work and get them professionally changed so I am happy they will be installed to a very high standard.

I have no means of testing the current chips as they are not accessible when the board stack is connected together in the machine hence the shotgun approach.

Looking at the datasheet for the RAM (TC518128CFL-80 as in the eBay link and not TC518128BFL-80, correct?), I see there is also a -70 version with a 70ns access time (as opposed to 80ns), but more importantly an improved power dissipation rating (385mW over 330mW).

1. Would the improved power dissipation rating ensure these chips ran cooler, and thus less prone to failure?

2. Would the faster access time still work? I'd guess yes, as it is an uprated component.

The -70 chips are more expensive, but if less prone to failure could mean a more robust repair thus cheaper in the long run.

Any thoughts on this?
 
I usually on other cards more "simple" tend to use the best components, such as capacitors with voltages greater or smaller chips with less access times, but in these complex boards, if is possibile, usually use only the same components, i see that these pcb are very choosy with non-specific components ...
You could avoid the heat by using an extra fan
 
Other data to repair pcb daytona gfx:

If you have graphic problems (cars confused or not present), you must change the ram marked in red;
If you have small graphic problems (lines or edges are not correct) verify that soldering near the custom chips 46 & 47 there are ok (marked in green)
If you have problem in the words in the screen you must change the rams marked in yellow


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