Backup RAM issue on MV1A

littlecharlie

Quiz Detective
Joined
Jan 10, 2018
Posts
81
Hi all, I made the battery mode on this board (replaced the rechargeable battery with a coin CR2032).
The backup RAMs and other chips are getting the 3V from the battery when the power is off.

But it is not working entirely fine.
I mean, after power off and on, the RAM will maintain some data but will delete some other.
For example:
1) the calendar date is not erased
2) the board enters in console mode (if the backup RAM wasn't working, the system will boot as arcade).
So far so good.

But the hiscores on the game are not saved, as well as some configuration options (like the blood on metal slug).

Any ideas? Maybe only one of the 2 RAMs is faulty?
 

littlecharlie

Quiz Detective
Joined
Jan 10, 2018
Posts
81
I tried that Xian, with no result
I then replaced the 2 backup RAMs and the 74HC32, with no results either

What I have found is that when in test mode, and inside the menu of the SOFT DIP, instead of the name of the game, there is some unkown characters ....

45c3c7s.jpg


So apparently, even though the game is playing fine, it seems the system does not recognize it, and therefore no information regarding the game is saved (hiscores, ect.)

What could cause it? I have cleaned the slot and the games.

I happens with all my cartridges.
 

ack

Ninja Combat Warrior
15 Year Member
Joined
Apr 9, 2009
Posts
538
Try letting the game boot up to the attract mode before going into test mode. What you are seeing looks like a known issue with unibios that will happen when you go directly to the test mode with a new cart.
 

littlecharlie

Quiz Detective
Joined
Jan 10, 2018
Posts
81
I take note ack, because this is happening to me quite often ...

But regarding this particular board, I found out that I bridged some pins when I changed the 74ls32. Once solved this, the board is working fine.

So, the replacement of the RAMs and LS32 seems to have solved thr problem.
 
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