Rengual's faulty MV4-FS & MV4-F

[BIG BEAR]

OK.Here are examples of the faulty MV4-FS:

MV4-FS Example 1
MV4-FS Example 2
MV4-FS Example 3
The above looks like LSPC /ZMC2 to me.

Here is a small video of the MV4-F
MV4-F
I told him to separate the top from the bottom to isolate the problem here.
Any suggestions are welcome here.
Thank you
BB

 

[ack]

For the MV4-FS I don't think it will have anything to do with the ZMC2, since that is specific to sprite data. The images show the issue is effecting both sprites and the fix layer. Additionally valid looking graphic data is being returned, its not the right ones. I would suspect an issue between the LSCP and its ram, or something between the LSCP and the carts P-Bus.

For the MV4-F best guess is an address line issue between the CPU and the active carts prog roms.

 

[Rengual]

Hello Guys. Thanks for having me!
Fortunately a am now able to talk with you. I hope my English is good enough to explain my problem to you properly.

So the MV4-FS shows this fractal picture. I don’t know where I can get spare parts in Germany for it. Maybe there is a way to check the chips before I am searching for others.

Now the MV4-F: I separate the upper from the lower board and the crosshatch pattern is showing perfect. The pattern is also showing when I have both boards connected without a game inserted.

In addition: the FS is showing that crosshatch also perfect.

 

[maki]

The MV4-FS has lots of ASIC for buffering and multiplexing on the top board.

I had really weird errors similar to the ones shown on a MV4-FS caused by multiple faulty NEO-244 (some inputs/outputs were faulty, sometimes more than half of them), and those are used for buffering.

MVS SLOT4FS graphics problem with games and mem viewer

Hi, have a MVS SLOT4FS here that passes the basic DIAG Bios checks, it has no sound and massive glitches when displaying either the mem viewer or running games. Everything looks perfectly fine without game and in the cross hatch/menu etc, still no sound though. Happens on all slots, didn't...

www.neo-geo.com

The ASICS are NEO-G0, NEO-244 and NEO-253 (multiplexer)

NEO-253 - NeoGeo Development Wiki

wiki.neogeodev.org

NEO-244 - NeoGeo Development Wiki

wiki.neogeodev.org

NEO-G0 - NeoGeo Development Wiki

wiki.neogeodev.org

My problems were solely (?) caused by faulty NEO-244, I had to lots of trial and error to figure that out:
- check if all slots are affected equally - they shouldn't IMO if its the ASICs, some will work worse or better
- once the "worse" slots are identified, find/trace out the ASICs handlings its signals, then swap the ASIC with the ones attached to the slots that are better working
- once you know which ASIC are faulty, replace them with working ones from donor boards or replacements from ebay/ali (NOS?) or furrteks clones. No replacements for the NEO-244 though, can only be harvested AFAIK from donors, which means lots of these boards are being cannibalised. If its just a few dead inputs/outputs on the NEO-244, consider replacing them with 74HCT244 or similar, but that doesn't scale well..

 

[Rengual]

Thank you for your answer. I appreciate this!
As I can see, a lot depends on 1. the spare parts and 2. on my fine soldering skills. Especially with the 2nd point, I'm not sure if I dare to do that. I hoped for an error on VRAM or something ;-), SMD soldering is still foreign to me. Since the solution lies here somewhere, I have to be sure here first, buy more equipment and get some practice. Alternatively, I'll have to find someone to help me here in my area. The German forums are also good here, but I'll have to see if I can find someone.

 

[Rengual]

News from the MV4-F:
It think I found a battery leakage. Can someone tell me the specifications for the spare parts? Is there a Part List or something?

What should I change? I would go with all marked parts. Please tell me your thoughts.

Is this causing the error?

 

[maki]

thats a well known problem

first thing is always:
REMOVE THE OLD BATTERY ASAP
don't wait for it to leak and damage the PCB (lots of times FUBAR)
no exceptions, nothing killed more MVS than the batteries, they'll leak

once its out, clean up the whole area, that includes the underside (remove the foam underneath, its soaked in the battery goo, use IPA or sticker remover/petrol for the foam)

then clean the PCB:
don't bother with acid (vinegar etc.) or other weird ideas
use plain water, lots of it, that will dissolve KOH (potassium hydroxide) in no time

I scrub the whole board like dishes, then I dry it in the oven at 50C - 60 C max.

once its clean you can inspect the traces and identify damages that need fixing

 

[Neo Alec]

News from the MV4-F:
It think I found a battery leakage. Can someone tell me the specifications for the spare parts? Is there a Part List or something?

What should I change? I would go with all marked parts. Please tell me your thoughts.

Is this causing the error?

You don't need to replace parts. You need to fix broken traces. Clean it, like maki mentioned, and then use a multimeter to check all the connections in that area of the board.

 

[Rengual]

Hey guys! I have new informations about my MVSs.
MV4-FS: I first cleaned the boards very thoroughly. There was a lot of dirt and nicotine at the upper board. I tried it again, and all four slots are working perfect right now. Is this possible ?

MV4-F: I removed the battery. I couldn’t find some interrupted traces. So I also cleaned the boards and hoped for the same result as the FS. Unfortunately, this was not the case. So I tried the slots. 1+2 are showing this reboot pattern. 3+4 are working without grafic issues. But the sound sounded as if only one track was running.
I think this can help you to narrow down the problem.

 

[Rengual]

I would like to tell you something more about the MV4-F.

The slots 1+2 still reboot like before. I went to the test menu. All slots were recognized (inserted 1-3)
You see the pictures. Slot 1 and 2 are very weired. Slot 3 is showing the normal menu.

But there was also a sound error in slot 3+4 as I said. Here are 2 videos. The first one is the faulty one. The second is on another good board. You can clearly hear the difference.

Any suggestions?

 

[Rengual]

Hello guys, unfortunately I haven't made any progress so far. Do you have suggestions?