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Toaplan snow bros faulty help pls

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dave11674 View Drop Down
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    Posted: 16 Mar 2019 at 1:05am

Hi guys, having a play with this board as i picked it up cheap.
It does not do a rom/ram check i just get a dull red screen.
Ive read the 3 proms but not sure what the custom prom is at the bottom @ 1D. Compared them with mame roms..
Tho i think in mame ic5 and ic6 are swapped for some reason.
Anyways rom 2-A and 3-A i compared with the roms from mame, but there are a few differences in the data, not much id say about 30 bytes in both 2-A and 3-A are different !!
Not sure if these differences will stop it booting....
But im thinking even with the differences i should get the rom/ram check ..
Ive ordered some 27c010 from ebay
So will burn the roms when they come and test

Ive done a reseat and clean test too. Same red screen

Can anyone shed any light on this in the meantime

On a side note the custom @9C has bent/snapped pins, but from repair logs i know this wont stop bootup as its part of the sound output amp.

Thanks

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dave11674 View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote dave11674 Quote  Post ReplyReply Direct Link To This Post Posted: 16 Mar 2019 at 8:22am
3 roms now compared and ok
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Post Options Post Options   Thanks (0) Thanks(0)   Quote ic3b4ll Quote  Post ReplyReply Direct Link To This Post Posted: 19 Mar 2019 at 5:11pm
Hi!

If it's not booting and your ROMs check out, I'd start by checking the data and address buses from the CPU to the RAM and ROM, including whatever logic is connected to them (namely to the CE and OE pins). If one of the work RAM chips is down or the access to them is compromised then the board is unlikely to boot.
If you one of the RAM chips shorted (unlikely as it would probably kill the ROMs too) the processor may be a goner and you'd have to replace it.
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