MV-1 board Memory Card Error

hard2obtain

Timid Neo Newbie
Joined
May 16, 2022
Posts
5
Hi to everyone

I have some MV-1 (1 slot) Neogeo boards that previously have the famous BACK UP ERROR, so i change one or both 58256 chips on those boards but that error now changes to MEMORY CARD ERROR. The problem is this boards doesn´t came with a memory card slot or any port to use them.

I changed the 58256 chips with a pair of replacements 43256 chips but have same problem, i checked continuity for broken traces and all seems to be ok, checked for shorted pins, transistors, diodes, capacitor, etc, but all of those have correct readings.

At this point im stuck with this error so I just wonder if anyone here knows how to fix that error.

Thanks
 

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ack

Galford's Armourer
10 Year Member
Joined
Apr 9, 2009
Posts
464
The 2 large black idc ports on the left side of the board are where you would normally hookup an MV-IC memory card board/cables. Check to see if you have bent/touching pins in those connectors.
 

maki

NEST Puppet
Joined
Jan 1, 2022
Posts
171
Looks like you have some bent pins on the NEO-ZMC2 PRO-B0, make sure that they aren't shorted with each other.

Edit:
in 38 and 39 should be NC, so ignore that
 

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Last edited:

hard2obtain

Timid Neo Newbie
Joined
May 16, 2022
Posts
5
Looks like you have some bent pins on the NEO-ZMC2 PRO-B0, make sure that they aren't shorted with each other.

Edit:
in 38 and 39 should be NC, so ignore that
Thanks for the reply Maki

I previously fixed that dent in the PRO-B0 chip, now only looks bad but isn´t shorted and making good contact with the pads.
 

hard2obtain

Timid Neo Newbie
Joined
May 16, 2022
Posts
5
The 2 large black idc ports on the left side of the board are where you would normally hookup an MV-IC memory card board/cables. Check to see if you have bent/touching pins in those connectors.
Those ports looks fine, also checked his traces
 

ack

Galford's Armourer
10 Year Member
Joined
Apr 9, 2009
Posts
464
The board thinks there is a memory card installed.

Check PRO-B0 pins

88 = memcard CD1
89 = memcard CD2

Those pins are used to detect when a memory card is inserted and they goto the IDC connector nearest the cart slot. With no card installed they should be high, but not sure what generating the high signal. Maybe the PRO-B0 has an internal pull up?
 

hard2obtain

Timid Neo Newbie
Joined
May 16, 2022
Posts
5
The board thinks there is a memory card installed.

Check PRO-B0 pins

88 = memcard CD1
89 = memcard CD2

Those pins are used to detect when a memory card is inserted and they goto the IDC connector nearest the cart slot. With no card installed they should be high, but not sure what generating the high signal. Maybe the PRO-B0 has an internal pull up?
Ok Ack, ill be checking that this week on both of the boards i got the same problem. Just in case i got another donor board to get a replacement PRO-B0 chip to test.
 

hard2obtain

Timid Neo Newbie
Joined
May 16, 2022
Posts
5
The board thinks there is a memory card installed.

Check PRO-B0 pins

88 = memcard CD1
89 = memcard CD2

Those pins are used to detect when a memory card is inserted and they goto the IDC connector nearest the cart slot. With no card installed they should be high, but not sure what generating the high signal. Maybe the PRO-B0 has an internal pull up?
Nop, there´s no signal on my logic probe either Hi or Lo, actually i don´t have any signal from pin 70 to pin 90
 

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ack

Galford's Armourer
10 Year Member
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Apr 9, 2009
Posts
464
hrm are you sure your logic probe was hooked up right? It would be very weird if all of 70-90 were dead. 70-87 are inputs from the joystick/buttons and should be held high by those CRE401's next to the joystick ports unless buttons are pressed.
 
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