Color RAM error on Taito Chase HQ

vintagegamer

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Looking for pointers on what chip(s) could be causing this error. Game tries to boot and results in "Color RAM Error" displayed on screen.

Any help would be greatly appreciated!
 
Replace the color RAM. ;)

Seriously though... follow the outputs back to the latch/output chips and follow those backwards and you'll find the color RAM.

On many boards it's a simple 2018 SRAM running around 35 to 55ns. Look for dark spots in the center of the chip or ones running excessively hot compared to the others. (These chips run hot anyways...)

RJ
 
Thanks RJ- I have not yet spotted any 2018 chips on the boards but hope to locate a schematic later today. Appreciate the help.
 
Womble has pointed out that he believes that the location or my problem RAMs are at IC2 and IC3. I have looked on the boards I have and at IC2 and IC3 on the main pcb (not the video pcb) I have 2 chips reading TMM2063AP70. I am trying to find a schematic to confirm, but it sounds like these are my problem children. Stay tuned as I make progress.
 
They are, but be careful of the chips physical size, many 6264s are the same width as EPROMs, the 2063 is the slim version, Toshibas wide version was the 2064, same pinout but different size.
 
You can find 12, 15, 20, or 25ns versions on older 486 motherboards used as cache RAMs. :)
 
Thank you to all of you for the help. I don't have any old pc motherboards anymore and i checked a sega shinobi pcb i have and it has 2018s on it but no 2063s. I'm guessing the 2018s can't be used as replacements for the 2063s?
 

On pg 7 of this AWESOMELY HELPFUL document, someone wrote "color RAM" next to IC3 in the middle of the page. The same type of chip is above it at IC2 so, do I really need to swap both? Or is the IC3 the only "color RAM"?

I'm trying to hold out until tomorrow to buy the RAM because there is a shop on my way home from work that might have that RAM hanging right there on a peg in the store. As usual with my luck, they are closed on Sundays. Sonofa........ :(
 
They are both the colour RAM, only of the chips may be bad, or both, or I should say neither. It's not guaranteed they are the fault but I would rate it as highly likely. I doubt you will find replacements anywhere retail, these chips were obsolete 20 years ago.
 
I have acquired another Taito board with 2063 chips on it, the only concern is at the end of the part # they have a "10" suffix where the ones on the Chase HQ board have a "70" for the suffix. The rest of the part number is the same. Can I use these to replace the chips on the Chase HQ board (I hope???) ?
 
I have acquired another Taito board with 2063 chips on it, the only concern is at the end of the part # they have a "10" suffix where the ones on the Chase HQ board have a "70" for the suffix. The rest of the part number is the same. Can I use these to replace the chips on the Chase HQ board (I hope???) ?
Not guaranteed to work. The general rule with RAM is that it should be at least as fast as what you're replacing (-10 is actually 100ns).
 
That's the general rule yes, but components are chosen by board manufacturers based on functionality as well as price, if for some reason the faster SRAM was cheaper when they were doing a production run then the board will have faster SRAM chips than it actually needs.

Of course you have no way to know what the critical speed actually is, but if the CHQ board you are thinking of taking the chips off uses the slower speed for its colour RAM then you know it is ok for the other board. If its coming from a different board or another bank of RAM on the donor CHQ board then it may not work.

Also - based on my experience any TMM2063s you find on unknown boards are likely to be bad, they are most likely the reason why the board was relegated to the scrap pile.

As there you have question marks over the health of the donor chips and their speed I would recommend fitting sockets on the board you are fixing so you can try a few chips and speeds until you find a combo that works.
 
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