NEO-MVH SLOT4 Cross hatch issues

[Reluctant9676]

Hi All,

I have a NEO-MVH SLOT that is stuck at the cross hatch screen and I'm a bit stuck what to do next.

Things I have tried:

1. Checking continuity on connectors between top and bottom board. Found two broken traces and fixed them (well they pass continuity). (see first picture, first time soldering)
2. Cleaned slots.
3. Cleaned carts.
4. Checked DIP switch 1 is off.
5. Battery already removed and continuity seems good.
6. Installed debug BIOS, it reports everything is okay (but I don't have a cart to hack apart to do end to end test).
7. Replaced bios with new Uni Bios 4.0 (see second image, attached is memory dump, I don't think it looks right.).

I'm a tad bit stuck and am open to any ideas or suggestions on what to further check. I choose this as a bit of an electronic learning exercise. so please assume I know almost nothing

Thanks!
R

 

[maki]

lots of these traces look very corroded, and thats just a tiny spot on the PCB

its your first time soldering and it shows, unless you're willing to go through the learning curve to actually learn it you're better off with giving that to someone experienced fixing this stuff

if you're up for the challenge, you should use leaded solder, AWG 28 and lots of flux, its a craft and needs lots of practise, things are gong to break while you practise, so practise on scrap HW or get some practise kits from eBay/Ali/Amazon
if you practise on this PCB you will ruin it, these are tricky

check the continuity of each of these traces in the pic, the completely brown is very suspicious, so are the gtaces that have darks spots

 

[Reluctant9676]

Hi thanks for the feedback.

I've check all of those traces and they appear okay. All of them make a connection and I followed this

https://www.neo-geo.com/forums/inde...ontribution-to-the-crosshatch-problem.121159/

list of pin outs to check every end point.

I have some finer wire on order and I was using leaded solder: 40% 60%. Agreed its terrible but continuity checks out okay. I also checked to make sure those pins weren't connecting to any of their neighbours via my poor soldering.

 

[Neo Alec]

What tool are you using to check continuity? When I was starting out, I didn't know how to use my multimeter, and I thought any reading at all meant continuity. I finally learned that you have to look for the minus sign to the side of the number that indicates continuity.

 

[ack]

what game was inserted for that memory map picture?

 

[Reluctant9676]

What tool are you using to check continuity?

Interesting, I could possibly be reading it wrong! (that would be great if I am). I'm using a QM1527. I believe the unit beeps if continuity is good? I'm using the option as indicated in the photo:



From the manual it says:

CONTINUITY CHECK​

Touch the test probe tips to the circuit or wire you wish to check. The
maximum value of resistance under check will appear on the screen. If
the resistance is less than 30Ω, the audible signal will sound.

Manual is here: https://www.manualslib.com/manual/1855079/Protech-Qm1527.html?page=8#manual


What game was inserted for that memory map picture?

I think it was metal slug but I cant be sure, I didn't realise it changed based on the cart. I though those values were the initial memory state of the unit as a whole. I have a few carts: Metal Slug, Fatal Fury, Art of Fighting, Amakusa's revenge: samurai showdown, Banana Cart 161 in 1. Happy to regrab the memory picture which cart would be best? I can do multiple if it helps

Thanks for the feedback everyone!

 

[maki]

I believe the unit beeps if continuity is good?

They beep if the resistance is lower than 100 Ohms, you still need to check the reading itself.

Edit:
According to the manual, yours will beep when the resistance is 30 Ohms or lower

 

[Heinz]

Even if you have continuity ie. signal sent and received down a particular trace/wire/what have you, it is not necessarily an indicator that it will perform as expected if corroded.

The wire you have used for trace repair is gigantic, think intercontinental undersea cable to connect your pc to a switch.

 

[Reluctant9676]

Thanks everyone!

According to the manual, yours will beep when the resistance is 30 Ohms or lower
Would that be okay then?

Even if you have continuity ie. signal sent and received down a particular trace/wire/what have you,
I was worried that might be the case, Is there a more fool proof way oh know the connection is okay? Most of the posts I have come across just say "fixed trace blah" and they seemed to get their system working.

The wire you have used for trace repair is gigantic
Totally agree, I have smaller wire on order, AWG 28. Last time I ask a sales person. Would the thicker wire be causing issues?

 

[ack]

I think it was metal slug but I cant be sure, I didn't realise it changed based on the cart. I though those values were the initial memory state of the unit as a whole. I have a few carts: Metal Slug, Fatal Fury, Art of Fighting, Amakusa's revenge: samurai showdown, Banana Cart 161 in 1. Happy to regrab the memory picture which cart would be best? I can do multiple if it helps

Can you do metal slug and fatal fury. That memory location is from the P1 rom on the cart. From the picture you posted it looks like data line d2 is stuck high. You also appear to have an address line issue, which is causing reads to get mapped to some other part of the P1 rom.

 

[Neo Alec]

Even if you have continuity ie. signal sent and received down a particular trace/wire/what have you,
I was worried that might be the case, Is there a more fool proof way oh know the connection is okay? Most of the posts I have come across just say "fixed trace blah" and they seemed to get their system working.

This concern is a bit too advanced and nitpicky for a beginner. I would say if the traces pass the continuity check and a visual inspection, that is good enough for now.

 

[Reluctant9676]

Can you do metal slug and fatal fury
Thank you and sure can! Attached, I captured from 000100, I assume that is the right thing to do? I also noticed the mem viewer wont work if less than four carts are inserted, not sure if that is normal? Also attached a couple others because I had to fill out all four slots anyway.

This concern is a bit too advanced and nitpicky for a beginner.
yeah fair call, well hopefully I figure it out before it gets to that. To be honest if I get really stuck I will send it off to be repaired, I just enjoy fixing things and learning.

Thank to everyone for the suggestions and help so far, really helps.

 

[ack]

- All slots seem to have data d2 stuck high or floating
- Address 0x000100 is getting mapped to 0x020100, indicating address line A17 is stuck high or floating
- Something is wrong with your slot select lines, such that slot 1 is mapping to slot 3 and slot 2 is mapping to slot 4. Likely one of the slot select lines is stuck high or floating. This also explains 'mem viewer wont work if less than four carts are inserted', when the bios tries to select slots 1 or 2 the board is actually activating slots 3 or 4.

 

[Reluctant9676]

Sorry, your going to hate me.

All slots seem to have data d2 stuck high or floating
Is this a trace or particular chip? I tired googling but not 100% I'm looking at the right things.

Address 0x000100 is getting mapped to 0x020100, indicating address line A17 is stuck high or floating
Same as the above, sorry. I really appreciate your help on this.

Something is wrong with your slot select lines, such that slot 1 is mapping to slot 3 and slot 2 is mapping to slot 4.
Ahh interesting! that certainly explains the weird behaviour.

I do suspect we are getting out of my skill set area (which let's face it isn't hard ), but would appreciate understanding what is going on.

 

[maki]

Getting out of your skill set isn't dangerous unless you're wilding a soldering iron

These old consoles work with parallel busses for addresses and data.
"A17" is an address line, "D2" is a data line.

They all have to work for the MVS to function properly, but on yours they are interrupted ("floating"), ack told you which ones, finding them involves reading the pin outs and schematics.

Category:Chips - NeoGeo Development Wiki

wiki.neogeodev.org

Schematics - NeoGeo Development Wiki

wiki.neogeodev.org

sometimes you'll find a textual list here which is really helpful

All in all you're out of your depth, starting with the soldering skills and basic theoretical background.
You can learn all that, it's going to take time, you'll need some practise PCBs and lots of time to actually practise.

You still haven't shown any other pics of the PCB, that one you've shown is not for beginners IMO, but if the rest looks similar, use it for parts.