Neo-Geo MVS 4 Slot BRam Unwritable Error

ICE_MAN_27

n00b
Joined
Jun 3, 2021
Posts
2
Hello All,

Just wondering if anyone can help me with this issue im getting with my 4slot

When I power it on it get:

Backup ram Error

Address 00D00000 Write 5555 Read FCC0

Ive not put a diagnostic bios in and tested and get the below,

BRAM DATA (Lower) UNwritable)

Address D00000 Actual: 00C0 Expected :0000 Passes :000000

Ive tested the VRAM & palette all pass ok

Is this just a case of changing 2 lower Chips? Or could it be something More?



Any help would really be appreciated Thank you.
 

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ack

Ninja Combat Warrior
15 Year Member
Joined
Apr 9, 2009
Posts
538
What do you get when you power on the diag bios and let it auto-test?
 

ack

Ninja Combat Warrior
15 Year Member
Joined
Apr 9, 2009
Posts
538
I would check for activity on the WE pin of the chip with a logic probe.

This should be were they are connected to

BRAM Lower pin 27 (WE) <=> 74HC32 @ D10 pin 8
BRAM Upper pin 27 (WE) <=> 74HC32 @ D10 pin 6
 
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