mask ROM - replacing a 42-pin ?

I

IronGiant

Armored Scrum Object
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Jan 10, 2004
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This is a sod - just been fixing various faults on a Konami Simpsons board and the 42-pin mask ROM at location 12N is faulty, so causing some sprites problems.

Short of some miracle enabling me to find a working ROM from an otherwise well screwed Simpsons board, is there anything that I can use to replace the duff mask ROM ?

The type of mask ROM used is equivalent to a TC538200P (8M, 16 Bit).

Any ideas please?

Ta.
 
andy251203

andy251203

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Well, if you're lucky the maskrom will have the same pinout as it's eprom equivalent. I'm guessing you'll need a 27c800 or 27c160, not sure.
 
channelmaniac

channelmaniac

Mr Neo Fix-it
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Try resoldering the ROM. I've seen some crappy solder on Konami boards and have fixed some ROM problems by resoldering them.

If that's not it, before you go to swapping out the ROMs, check for stuck data lines on the ROMs. I've had dead custom chips on those Konami boards cause the ROM errors too. If that's the case then you'll have to find a replacement chip on a scrap board.

RJ
 
I

IronGiant

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Thanks, tried re-soldering but no luck.

No stuck data lines either, no bad tracks, etc.

I'm just hoping it's not a bad custom .............
 
mainman

mainman

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Konami boards use 27c800 eproms as a drop in replacement, this is from actual experience and not guess work.
 
J

JMKurtz

Tech Support Moderator,
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27C800 is 40 pin, right?

27C160 (16Mb) and 27C322 (32Mb) would be 42 pin replacements for most 16 bit mask roms.
 
I

IronGiant

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Thanks. 27C800 is definitely 42-pin as I have a datasheet for it. The pinout is correct too.
 
J

JMKurtz

Tech Support Moderator,
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Just looked it up - 27C800 = 42 pin. Never knew that as I don't think I've ever used one :)


JMKurtz said:
27C800 is 40 pin, right?

27C160 (16Mb) and 27C322 (32Mb) would be 42 pin replacements for most 16 bit mask roms.
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