Metal Slug 2 MVS problem

auberwn

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Feb 13, 2017
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I'd like to ask for your help.
I've got a Metal Slug 2 cartridge which has a problem.
Unibios is reporting an illegal instruction on address 002E0000.
Is that on the P ROM?
I've modded the cartridge with the speed fix but I've put a socket on it and I can switch to the original chip - however I get the same error with the original one.
It used to work fine even after the mod and I put it away a few months back and now that I tried to play again I'm getting this error.
I've double checked the soldering and run the soldering iron over them to make sure.
I've cleaned the edge connector as well.

I'd appreciate your help.
 

ShootTheCore

Bead Banger
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Feb 11, 2015
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Yes, 002E0000 is mapped from the P ROM. Check the soldering on your socket and also check the traces for each pin and make sure none of them are damaged. If you have a multimeter, put it in Continuity mode and check each pin on the P ROM for continuity between the pin and its destination.

Also, post a picture of both sides of your PCB if you can.
 

auberwn

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I've checked everythything again but I didn't find any continuity issues.
Could it be that the other chip (p2) has failed?

I've tried to grab some photos - apologies for the quality:

-edit- I've uploaded better versions below -edit-
 
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ShootTheCore

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Yeah, P2 could be your culprit as well. Use the UNIBIOS CRC check and compare the checksum values of the P chips against MAME.
 
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auberwn

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Yeah, P2 could be your culprit as well. Use the UNIBIOS CRC check and compare the checksum values of the P chips against MAME.

I run the CRC check and the last two places all have question marks:
Region: DF5D6FBC ??
Bank0 : 09D75B98 ??
Bank1 : 562E782D ??
Bank2 : 09D75B98 ??
Bank3 : 562E782D ??

Can you give me some general instructions on how I can compare the chcksum values against MAME?
 
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Niko

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I cant tell from the low res pics, but are you missing a jumper at J13?

Was that CRC check with the original P1 or the "Turbo" P1?
 

auberwn

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That's with the turbo P1. The chip is a 27C160 with the bin doubled - that might be the reason the CRC shows 4 banks (?).

I put the original in and I get:
Region: 2A53C5DA OK
Bank0 : 09D75898 NG
Bank1 : 562E782D NG
Bank2 : NOT USED --
Bank3 : NOT USED --

I sort of figured out how to check the CRC - it's right the on the roms.
The original ones have
P1: 2A53C5DA
P2: 38883F44
and the turbo P1
P1: DF5D6FBC
 
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auberwn

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J13 is there. Better images
 

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auberwn

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-edit- the following is not possible since P2 is not 1MB like P1. It's 2MB. -edit-

Is it possible to write both P1 and P2 on the 27C160 and run both that way?
Would it work if I cut the line going to P2 leg 11 (Enable) and direct it to P1 leg 42 (A19)?
 
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Niko

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If you've checked the continuity between the socket and edge connector, then I think your issue is either going to be a bad P1 rom or the rom legs not making good connection with that machine pin socket.
 

auberwn

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If you've checked the continuity between the socket and edge connector, then I think your issue is either going to be a bad P1 rom or the rom legs not making good connection with that machine pin socket.

Actually I checked the continuity with the chip in the socket (between the chip legs and the edge connector) - I just took it out to take the photos.

I'll burn a P2, install that and see what happens.

-edit- the P2 was dead. replaced it with a 27C160. Thank you all for your help! -edit-
 
Last edited:

Niko

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Actually I checked the continuity with the chip in the socket (between the chip legs and the edge connector) - I just took it out to take the photos.

I'll burn a P2, install that and see what happens.

-edit- the P2 was dead. replaced it with a 27C160. Thank you all for your help! -edit-

Interesting, glad you got it working.
 
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