Neo Geo MVS RAM locations - a preliminary document

So many people (myself included!) post messages here asking where the various RAM types are on their MVS boards that I thought it would be worth documenting the assorted RAM chip locations (ie for Work RAM, Video RAM, Backup RAM, etc) for the different board types. This can then be stored on someone’s web site or, if the mods are willing, put onto this forum somewhere. This will save an awful lot of duplicated posts and take a bit of the weight off the MVS experts who are very generous with their valuable time and experience in this forum. The information is mostly present on this forum but it’s so scattered about that it can take longer to find than the time it would take to replace a dozen 200-pin QFP SMT custom ICs ………… ;-) Okay, I exaggerate, but you get my drift.

This list is currently EXTREMELY preliminary to say the least – I’ve been going through the tech area of the forum searching for RAM related queries and it’s taken me a few hours so far – I’ve barely scratched the surface but, well, it’s a start. If anyone finds any errors (bound to be some!) or would like to add information please reply to this thread only with the corrections/information.

Eventually I may look into getting hold of some large-ish, high quality pics of all the MVS boards and edit them to add some box-outs and labels pointing to the RAM types – as they say, a picture is worth a thousand words. There’s some pics of all the MVS board types on hardmvs, unfortunately they are a bit too small or they don’t show the whole boards for what I have in mind. A pity. It’s also worth noting that I don’t have a 4 or 6 slot to verify any of the info related to those, but I do have various types of 1 slot and a 2 slot.

Anyhow, enough waffle, here goes for now – please click on the following link for a very preliminary and incomplete file – it’s an MS Word document. If anyone can’t handle this format please let me know and I’ll pop up a text version too. Revision 6 of the file is here:

http://www.mediafire.com/download.php?dmpjzxdr5xt

i can upload some pics or a 2slot a 1f

If they're nice and clear and a good size then yes please. Very many thanks.

ill make the scans at 400 dpi and provide links

Perfect, thanks.

Here's revision 2 of the document - you'll notice that there are some areas where I'm basically asking some of the MVS experts to confirm my findings, I've put:

– IS THIS CORRECT ????????????

besides those.

Also 'need data' is as it says, I need RAM locations and function data on these boards please.

Here's revision 2:

http://www.mediafire.com/download.php?dvthzzy09dg

Progress is being made, I do hope the experts can help out a little bit though (please?) even if it just means checking my document for errors - I will of course continue searching for missing info on this forum and update the file accordingly.

Thanks

Well, this has gone download like a lead balloon - seven downloads of the original document, three downloads of revision two and no comments on the content.

I really thought that this would have been helpful to a great many people yet I've received almost zero feedback (except for the helpful reply to supply some decent PCB images).

Oh well, someone had to at least try .............

thank you. ill get those scans out

youre doing a great job.. werejag you too for helping him, cool.
i downloaded it, but just to look at it. but im not an electro expert...

Thank you. 15 downloads so far.

So, can some of the tech experts here (channelmaniac, MKL, Nightmare Tony etc) PLEASE help out a bit by checking over the contents of the file and perhaps even adding missing info when you have a few minutes to spare?

I'd really appreciate it, plus it will help out you guys in the long term.

Thanks

I will.

For a text only version of the doc you need to reference the RAM by board location. If you look at the board you'll see a series of letters on one side and numbers on another. They make up a grid for chip locations.

RJ

Thanks very much for the feedback.

Any thoughts on the accuracy of the content re RAM locations and types for the assorted boards?

Accuracy isn't a problem. They are in the same place on each MV4 board.... same thing goes for the smaller MV4F. The trick is to find one of each board to document.

I have a 2, 2F, 4, 4F, and a couple of 1 slot boards over here that I can document.

RJ

That would be great - as you can see I've tried to document the 2FS and 2-01 so if you are able to confirm my findings that would be most helpful.

Your details on the 4 and 4F would also be most welcome.

Very many thanks.

MV-1FZ and MV-1FZS

Work RAM: RAM1 and RAM2 - IS THIS CORRECT ???????????? YES
Video RAM: RAM5 and RAM6 - - IS THIS CORRECT ???????????? YES
Backup RAM: RAM3 and RAM4 - IS THIS CORRECT ???????????? YES

All of these are KM62256CLG-7 - 28-pin surface mounted RAMs
Not necessarily, it can be from several different manufacturers (that use different codes for their RAM chips)

Additional Video RAM (fast Video RAM): RAM7 and RAM8 - IS THIS CORRECT ???????????? YES

Both of these are CXK5814P-35L - 24-pin DIP YES but the brand can be different

Colour Palette RAM: RAM9 and RAM10 - IS THIS CORRECT ???????????? YES

Both of these are XLJ6265AF-10SL - 28-pin DIP No, it's SMD
Here too different brands are used.

Sound RAM: RAM11 YES

A single BR6216B-10LL - 24-pin DIP YES

----------------------------------------------------------------------------------------

MV-1A

Work RAM: RAM1 and RAM2- IS THIS CORRECT ???????????? YES
Video RAM: RAM5 and RAM6 - IS THIS CORRECT ???????????? YES
Backup RAM: RAM3 and RAM4 - IS THIS CORRECT ???????????? YES

All of these are KM62256CLG-7 - 28-pin surface mounted RAMs
YES but it can be various brands.

Additional Video RAM (fast Video RAM): RAM7 and RAM8 - IS THIS CORRECT ???????????? NO, RAM7 and RAM8 is the color RAM. The 16k vram must be encapsulated in a GPU and it's not in discrete chips (5814) as on other boards.

Both of these are LH5168N-80L - 24-pin DIP, marked as 5814 on the PCB under each chip
No, LH5168N-80L is a 64k SMD ram used for the color pallette.

Colour Palette RAM: Don’t know! See above

Sound RAM: RAM9 YES

A single BR6216B-10LL - 24-pin DIP YES

Excellent, many thanks!

Have now revised the doc based on MKL's info and uploaded revision 3 here:

http://www.mediafire.com/download.php?1gw11rxlgdj

The NEO-MVH Slot1FZS board doesn't have the grid markings on it. Instead the chips are labeled on the silk screen:

RAM1 - Work RAM (62256)
RAM2 - Work RAM (62256)
RAM3 - Backup RAM (62256)
RAM4 - Backup RAM (62256)
RAM5 - Video RAM (62256)
RAM6 - Video RAM (62256)
RAM7 - Video RAM $8000 (5814)
RAM8 - Video RAM $8000 (5814)
RAM9 - Color RAM (Palette) (6264)
RAM10 - Color RAM (Palette) (6264)
RAM11 - Sound RAM (6116)

-----------------

MV1FS 1-slot:

Work RAM (62256) - H4, H5
Backup RAM (62256) - H6, H7
Video RAM (62256) - B4, B5
Video RAM (5814) - C6, D6
Color RAM (6264) - H8, H8 (bunched together at same grid location)
Sound RAM (6116) - K3

-----------------

MV2 2-slot:

Work RAM (62256) - E5, E6
Backup RAM (62256) - H3, H4
Video RAM (62256) - F13, G13
Video RAM (5814) - F12, G12
Color RAM (6264) - B9, C9
Sound RAM (6116) - K13

-----------------

MV2F 2-slot:
The parts don't exactly line up on grid.

Work RAM (62256) - D3, D4
Backup RAM (62256) - G1, G2
Video RAM (62256) - C7, C8
Video RAM (5814) - C9, D9
Color RAM (6264) - B8, B8 (bunched together at same location)
Sound RAM (6116) - K11

-----------------

MV4 4-slot:

Work RAM (62256) - G9, H9
Backup RAM (62256) - D9, E9
Video RAM (62256) - K9, L9
Video RAM (5814) - L11, M11
Color RAM (6264) - F4, H4
Sound RAM (6116) - L1

-----------------

For the RAMs:

The SMT (Surface Mount Technology) SRAM chips for Work, Backup, and Video SRAM are 32k x 8bit. Any JEDEC pin compatible 32k x 8bit SRAM IC will work as long as it is 120ns or faster speed.

This includes 62256, 43256, cxk58257, and others.

They MUST be SOIC type - not SOJ. SOJ has the leads turned under in a J shape and will NOT fit.

The 2k x 8 bit SRAM ICs used for the video SRAM are 2k x 8 bit JEDEC compliant pinout chips. Any chip of that type will work as long as they are 35ns or faster speed. This includes the CXK5814, CYC128A, and 6116 ICs, provided they are fast enough.

The 2k x 8 bit SRAM IC used for the sound SRAM is the same JEDEC type as the Video SRAM but is much slower. It must be 150ns or faster. The ultra fast 35ns ones that are used for the Video SRAM will work fine for a replacement but will be more expensive than a slow 150ns chip.

The 8k x 8 bit SRAM IC used for the Color SRAM (a.k.a. Palette RAM) is a JEDEC compliant SRAM IC. Any compliant SRAM IC of the same size and 120ns or faster will work. This includes ultra fast cache 64k RAM chips off of old scrap 386/486 boards.

When repairing a Z80 error message on the Neo Geo boards start with the Z80 processor as it's the most likely part to fail. For some reason SNK silkscreened the board with "Z80A" but yet used a slower speed rated "Z80" CPU instead. This part will fail over time as it will run hotter than the correct speed rated IC.

There are a lot more posts that could be put into your doc if you want to turn it into a generic repair doc for the neo geo. Search my posts in the Tech Support area and you'll find all kinds of repair tip gold.

I hope you include contributor names on the doc.

RJ

Well if your not just jerking with my time I can provide pics of every MVS mobo ever made, excluding those rare bootleg looking one slots.

Hi,

All that is excellent, very many thanks.

I'll incorporate all that info into the document and upload rev. 4 later today.

I was thinking of including repair tips but thought I'd rather get all the RAM locations documented first. Would also like to include a few examples of RAM chip failures and which chips would have been at fault depending on the error.

Naturally all contributors will get a mention - your name has been in the document from the first revision.

So I take it you would be interested in the pics, I ask because it will be a task as it require me to disassemble the 4 and 6 slots. Will not get to it until next weekend however.

mainman said:

Well if your not just jerking with my time I can provide pics of every MVS mobo ever made, excluding those rare bootleg looking one slots.

Click to expand...

Eh? How would I be jerking with your time? I think my document is proof that I'm actively doing something with this little project.

Thanks for your kind offer - at the moment I'd like to stick to a clear (ie so all board text can be read), large shot of each main board (with any cartridge slots and/or plastic or metal covers removed) so that I can annotate them with a few circled areas and a bit of text just to show where the RAMs are located. werejag has offered to upload some pics of a 2slot and a 1f. The bootlegs are of interest, but not at this stage of the project (but feel free to upload them if you like).

I'll probably end up having to put these on a web site as putting them into the Word document (or a PDF) might make it too large and unwieldy.

Actually, what do others think of this - should the annotated pictures go into the main document or hosted on web site?