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Gato

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Hello,

I have been getting Backup Ram Error messages from my MV1C.

00D00000 5555 557E
00D00000 5555 557F

00D00000 5555 5540

From my research it appears it is a lower-ram issue, possibly a broken trace. I got myself a multimeter but I'm not sure what I'm looking for when I use it. Any help would be appreciated.

I have a unibios so I am able to bypass it and (thankfully) still play my games.

Also, say I ignore the error messages, could ignoring "the backup ram error" messsage prossibly cause further problems to the pcb or games?

Thank you for your time.
 

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Replace a suspect is the first thing I do, but you can test the points if have alot of free time.
 
Replace a suspect is the first thing I do, but you can test the points if have alot of free time.
Thank you for the suggestions. When I test the points on the HC32 what will it be that I am looking for? I'm a noob at using a multimeter and am not quite sure which specific setting to use and what reading I'm looking for on the meter.
 
Replace a suspect is the first thing I do, but you can test the points if have alot of free time.
Thank you for the suggestions. When I test the points on the HC32 what will it be that I am looking for? I'm a noob at using a multimeter and am not quite sure which specific setting to use and what reading I'm looking for on the meter.
You need to know the schematic or get same board that is working well. Do a continuity test.


Replace the backup RAM. It's a common fault.
Most of cases that i get MV1C with BK Ram error the problem is HC32 or some bad trace around it.
 
Since I can see corrosion, I’m leaning towards bad trace. But listen to Apoc, don’t just shotgun repairs.
 
Replace HC32.
Replace the backup RAM. It's a common fault.
Guys, guys, please calm down. ;) First identify the cause (trace, RAM, HC32, etc.), then fix it. Of course you can get lucky by randomly replacing chips but that's not what I call repairing boards.
Also checking for continuity is quick, probably quicker than replacing the 74HC32.
Since I can see corrosion, I’m leaning towards bad trace. But listen to Apoc, don’t just shotgun repairs.
I agree but on Neo I've had 1 repair where a bad trace caused a RAM fault, and 20-30 dead RAM chips cause a RAM fault.

The bad trace was also caused when the bad chip was replaced on a battery damaged board

I don't feel like replacing the RAM is a shotgun repair when it has a huge failure rate. And if it was a bad trace, the error would be F or FF based on not being able to read one or more bits.
 
We’re trying to teach people the process in repairs, you’re focusing on the wrong thing.

I’d prefer to teach someone how to repair a board properly instead of blurting out answers because if you don’t teach them how to do it themselves, their next topic will be about a similar repair because they didn’t learn anything from the last repair.
 
the sram on neo boards is so bad, that i lift both and test them in a 28pin soic adapter on every board i get.
you will save yourself a lot of time because they are often bad.
same goes for the 4 through-hole rams too - but not so often.
 
the sram on neo boards is so bad, that i lift both and test them in a 28pin soic adapter on every board i get.
you will save yourself a lot of time because they are often bad.
same goes for the 4 through-hole rams too - but not so often.
It's not the SRAM itself, Neo needs very little power and RAM is the most sensitive component to power supplies running too high.

I have seen many different SRAM manufacturers on Neo boards and they all fail. The Sony SRAMs used for fast video definitely fail more often than most though.

I'll stop derailing the thread

As above, check traces, HC32 and the SRAM itself.
 
Too much drama. I don't like waste my time dealing with testing, but it's my method, as i said, i just replace who suspect and if it works, nice. Most of cases on MV1C, i repeat, on MV1C.

Of course, if it won't work, i will test the entire curcuit.

There's no RIGHT WAY when you are a professional, only the way that cost you less time.

BTW, you are free.
 
My MV-1C has repaired traces to the backup ram too. Definitely check traces first.
 
I'd replace both RAMs. The part number indicates it is a 3.3v part. Most likely they have been over-volted to death. I would also flip over the board and check if work RAM and slow VRAM are also low voltage. Having "LV" in the part number is usually a good indicator of a 3.3v part.
 
So I contacted TimeHarvest (the vendor of the CBOX/SuperGun unit) about the error message and they told me:

TimeHarvest' said:
Because it is used MVS motherboard, it is has been discontinued for 20 years, no new one, so I can't predict when the RAM IC will defective.


The MVS motherboard have total 6pcs RAM IC, i will send you all 6pcs RAM IC, you can replace this two RAM IC first, because usually this two RAM IC have problem, thank you.
I knew I was buying a refurbished product, so I thought that was cool of them to offer replacement ram for free, but it is possible that it could not be what they specified (HC32 maybe?).

They also provided the attached image (looks like the underside of the MV1C PCB). As has been stated here, I really don't want to remove chips that can very well be fine.

Is there a schematic/tutorial for the MV1C that I can follow to test the current ram? Like, perhaps a youtube walkthrough or detailed PDF? ( I have come across this: https://wiki.neogeodev.org/index.php?title=Schematics )

Thanks again, you've all been very helpful.
 

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Hey buddy this should be continuity on your meter. Try this setting and touch the probes together your meter should beep.
 

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If it's refurbished, shouldn't they replace the defective board? I take refurbished to mean it's sold as working.
 
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