Sega Naomi Zero Gunner 2 Cart IC7 - IC8 BAD

[glstar]

Hi.
I have a Zero Gunner 2 cart with IC7-IC8 BAD.
Seems that the problem is related to the mpr-23687 IC4.
Since this is a masked rom, could someone tell me what i can use as replacement chip?

[TylerDurden67]

[glstar]

Oh well....

So what can i use???

[TylerDurden67]

Its tsop48 128Mb,right ?
Equivalent arent plug and play,you need to modify à little bit

[glstar]

Its tsop48 128Mb,right ?
Equivalent arent plug and play,you need to modify à little bit

It should be 64mbit 48 pin tsop.

[TylerDurden67]

MX26L6420 are OK for that capacity.
Just be sure to add an resistor or 2 diodes in serial since mx are running at 3.3v and originals maskrom runs at 5v

[glstar]

This is the cart:


This is the maskrom chip that should be bad:


This is some measurement made on the chip:


How to check if the maskrom is really bad?
How can i read this one?
Which is the rom (or other) i can use to replace it?

[glstar]

Just for information...
This is what Guru tell me about this problem....

they are 128M.

there is only one equivalent.
it is OKI MR27V12800J

[TylerDurden67]

Its tsop48 128Mb,right ?
Equivalent arent plug and play,you need to modify à little bit

That what I was thinking about but since you told me there are 64mb.
Thanks for your information about equivalent BTW