MV-1ACH problems

Joined
Oct 1, 2018
Posts
7
Hi folks, another first-time poster here.

I recently restored a gutted arcade cabinet (something I have wanted to own for oh about 35 years now), and needing something to put in it, I bought an MVS from ebay and a 161-in-1 from AliExpress, which seemed like a pretty good place to start.

The MVS turned out to be a MV-1ACH and it isn't in great condition. There are a few scratches on the bottom of the board which might be a potential source of trouble (if not now then in the future), and more worryingly some of the surface-mount capacitors on the bottom seem to have been dinked right off the board and are missing.

It boots, but it's really glitchy. Some games almost work. Most suffer from random crashes, predictable crashes, flickering, missing or incorrect sprites, wrong palettes, corrupted level data or other strange behaviour. It's kind of interesting but very much less than ideal!

Not having a working setup makes it hard to tell exactly what is going wrong although obviously those missing capacitors are not helping matters, but perhaps they aren't the only problem.

I know bad cart connections can cause this kind of behaviour, and the Neo-Geo has the mother of all cart connectors, so I went to town with contact cleaner but that hasn't helped.

The power supply is a new 10A arcade supply, I tried running the +5v a little hotter but that hasn't helped.

The 161-in-1 is a revision 2 - I haven't done the audio mods, but I did bridge the two pins which it was recommended to bridge, but that hasn't helped either.

It's hard to know whether to blame the 161 or the MVS, since I don't have another cart or another system to test against. But since the MVS has actual visibly damaged components, that seems like the most likely culprit.

Thinking perhaps I'd just been unlucky, and before I invest too many hours in trying to fix something I might never get working, I thought well, maybe it would be easiest to just get another one and see how that behaves. Then I hopefully could confirm that the cart isn't faulty. So I bought another MVS from ebay - against my own better judgement it was another MV-1ACH, but they are the only ones who don't charge an arm and a leg for postage to New Zealand.

This one looks to be in a bit better physical shape, although it ALSO has some missing capacitors on the underside. Ugh. I gave it a thorough slot-cleaning and... well, it just sticks on the crosshatch screen. I don't think it sees the cart. With the UniBios in, it goes to the UniBios crosshatch screen, and going from there to the memory monitor produces a page of garbage.

So yes, it's worse than the first one. Wonderful.

Well there's nothing for it now, I can't turn back, I don't want to buy a third one, I guess I'm going to have to try to fix one of these damn things. And I guess the place to start is to replace those missing capacitors which I am sure must be making the system more unstable even if it doesn't seem to have killed it. I have no experience with this titchy surface-mount stuff and don't even know what to replace them with.

Help guys!
 

Dropwire

Kuroko's Training Dummy
Joined
Jul 27, 2018
Posts
75
Hello good sir, for starters the fact that your getting the crosshatch is promising. It could be worse...

Can you upload some images of the boards in question with the missing caps? As some of the spots where it seems a capacitor should be were not necessarily populated originally. Also there are some great scanned images of all the MVS boards at http://www.mvs-scans.com/index.php/Main_Page#MVS_Hardware this is a great resource site along with Neo Geo Dev Wiki https://wiki.neogeodev.org/index.php?title=Main_Page

Do you have the ability to burn EPROMS ? If so you may want to Burn a Diagnostic Bios, the info can be found here http://smkdan.eludevisibility.org/neo/diag/ it is a great tool for troubleshooting, there is also a second EPROM you can burn but will need to get a standard NEO GEO cartridge to install it in. All the info is on the SMKDAN site.

Just a few quick points:
- Do you have a Digital Multi-Meter ? a Logic Probe?
- Are you using a soldering iron with adjustable temp? or do you have a hot air station?

There are many great folks on this site, with vast knowledge in troubleshooting and repair. Should be able to get you on track.
 
Joined
Oct 1, 2018
Posts
7
I'll get some pics up soon.

I do not have the ability to burn EPROMs but it's the sort of thing a crazy fool who is starting to collect arcade hardware likes to do, so I've thought about getting set up to do that. In for a penny, right? But for now at least, no.

I do have a multimeter but not a logic probe. I should get a logic probe too.

I only have a basic non-adjustable soldering iron. I like learning about electronics and I like fixing up old hardware, but it's all been older thru-hole stuff up until now. If I had more money I'd have all this gear already; I'm sure I'd use it. I'm just on a tight budget.

Yeah, I see that people here really seem to know these machines inside out. Always a privilege to learn from a pro. Cheers people.
 

Dropwire

Kuroko's Training Dummy
Joined
Jul 27, 2018
Posts
75
I'll get some pics up soon.

I do not have the ability to burn EPROMs but it's the sort of thing a crazy fool who is starting to collect arcade hardware likes to do, so I've thought about getting set up to do that. In for a penny, right? But for now at least, no.

I do have a multimeter but not a logic probe. I should get a logic probe too.

I only have a basic non-adjustable soldering iron. I like learning about electronics and I like fixing up old hardware, but it's all been older thru-hole stuff up until now. If I had more money I'd have all this gear already; I'm sure I'd use it. I'm just on a tight budget.

Yeah, I see that people here really seem to know these machines inside out. Always a privilege to learn from a pro. Cheers people.

No worries, you have the basics and that’s enough to get started. You can get more stuff for your tool box later as you get further into it.

Some basic troubleshooting to get you started.

- Don’t let SMT components scare you, they are just like their through hole cousins, but require different care when working on them. Check out some YouTube videos on soldering techniques for SMT with a standard soldering iron.

- The dc voltage, resistance, and continuity check on your meter will become your best friend.

- With some sort of magnifier (Loup , magnifying lens) or camera with zoom, visually inspect all the circuit traces, this can be tedious but well worth it. Any minor gouge, scratch, cut, or break can cause a problem.

- If any trace looks suspect, check it using the continuity function of the meter, the beep will indicate there is a connection. Then re-check it using the resistance function, for a good trace you want a value as close to 0 as possible (example .18 ohm is good, 2 ohms not so good). If you find a bad trace you will need to use fine gauge wire to repair it or provide a new connection between the components that were on that path.

- Do your boards still have the battery on them? If so, diligently check that area as it is well known that the batteries can go bad and leak, causing damage to the area and the components around it. You can even remove the battery as a precaution during your troubleshooting.

- Check the pins and connections between the cartridge slot board and main board, also check the gold connections in the cartridge slot to make sure none are bent or corroded.

- Aside from the Uni-Bios, do you have the original bios for the boards?

- You should look into obtaining a standard MVS cartridge (game) for testing, anyone will do. Since the 161-1 can be glitchy and not really reliable for troubleshooting.

- As you do not have the ability at this time to make your own diag-bios you can ask on the forum if anyone local to you can make one for you if you provide them the blank EPROM. If you can’t find anyone, I can make one for you, however it will take some time considering our locations.

- Patience, patience, patience, take notes of your work, log you progress, this will help you immensely. Always note your test results.

- once you upload some images folks on the forum can view them and possibly offer advice.

- Almost forgot, another great resource is GadgetUK’s videos on YouTube, they are invaluable. Definitely recommend giving them a watch.

Hope some of this helps, I’ll keep an eye out for your images. Good luck.
 
Joined
Oct 1, 2018
Posts
7
Here's the undersides, showing the missing caps.

neogeo1.jpg

neogeo2.jpg

I haven't properly investigated the topsides yet. I suppose if those electrolytics are getting old it could be affecting stability too. However it doesn't seem to be a general stability error.

The weird thing is that some games seem to run fine or almost fine (in the first MVS at least). Metal Slug 4, for example, seems to be ok, at least in the early stages. Metal Slug 1 is a mess and can't get through the demo loop without crashing. I thought maybe the cart ROM is bad, except that, although the glitches are mostly predictable, it's not always the same.
 

RyuX

Crossed Swords Squire
Joined
Sep 19, 2018
Posts
179
Just as a quick side note.. I also bought a 161 in 1 from Aliexpress which also crashes on most of the games! Never use a multi cartridge to test a board - just buy a cheap Cart like I did (Soccer Brawl, etc.) that is known to work.

I had the biggest issues with the 161 in 1 even after modding. On my MV-1C it will not boot and on my MV-1FZ it will crash on most games especially on Metal Slug on the Demo Loop.

Other than that - inspect the board with a loupe and a light and see if on the scratched area the traces are bad.
A multimeter with continuity / resistance test will serve you well for this.

Once you get a EPROM Burner (I got a TL866A) and a AT27C1024 EEPROM you can try to burn the Diagnostics Bios from here (http://smkdan.eludevisibility.org/neo/diag/)
This will help you narrow down things - however this is only as a starter as it will not check the whole board.

When getting glitches try to press on top of parts and see if it changes the glitch to narrow down which parts to focus on.
Also bending the board a little bit might change glitches.

Hope you figure it out soon - first thing for sure is to get some proper tools to work with.

I myself have the following in use on a daily basis for the neo geo:
* Reflow soldering station (hot air)
* Soldering Station (normal)
* Multimeter
* Logic Probe

Then try go get your hands on schematics and pinouts to get an idea where the traces are supposed to go.

Cheers
Patrick
 
Joined
Oct 1, 2018
Posts
7
- I have beeped out the corrosion spot and scratch I indicated on the first board, but not checked the resistances as yet.

- I will check out the battery area and remove the batteries.

- I haven't beeped cartridge slot to board yet, will do. Slot connectors look to be undamaged.

- I do have the original BIOS chips, yup. The BIOS of the second one is now in the first one; it behaves just like it did with its first BIOS.

- I've been looking for an original cart to test. Trouble is, local ones are uncommon and tend to be expensive, and cheap ones on ebay tend to charge a lot for postage. I'll keep looking.

- If there's anyone in New Zealand reading who would be willing to burn me a diagnostic BIOS I'd be most grateful. Even if you can't burn me a ROM I'd be interested to hear if there are other NZ collectors out there, because it sure is nobody I know.

- I'm in no great hurry. Actually I'm torn whether to do this first, OR go ahead and buy this Blood Bros arcade board which has come up... OR do the smart thing and spend more time doing the paid work which funds this hobby :/ (that was the rationale behind buying the second MVS...)

Meanwhile I've picked up a Green Beret board which is working but needs a recap, and I need to do a yoke width adjustment on my monitor chassis. And I still need to make a 4 button control panel for the Neo Geo for that matter. I tend to work on these things pretty slowly, it usually involves waiting for the post. And obviously once I get the Neo Geo working that will be rad and I won't get any work done ever.

- GadgetUK's videos are better than TV.
 
Joined
Oct 1, 2018
Posts
7
I hope it's not a faulty cart after all! Or two broken systems AND a faulty cart.

So much harder when you don't have known working stuff to compare. I was hoping the second MVS would be my known working one, ha.
 

RyuX

Crossed Swords Squire
Joined
Sep 19, 2018
Posts
179
I hope it's not a faulty cart after all! Or two broken systems AND a faulty cart.

So much harder when you don't have known working stuff to compare. I was hoping the second MVS would be my known working one, ha.

Just out of my experience - the 161 in 1 from Aliexpress has a very bad quality control.. Like mentioned earlier mine will crash all the time even with the mods and does not even boot on a MV-1C. I reflowed the cart many times and did ultrasonic cleaning but it is just a dead puppy..
 
Joined
Oct 1, 2018
Posts
7
Did you get another one and try again? Or a more reliable source? I would like a 161 as the pick 'n' mix function on the UniBios is great, or rather it would be.
 

RyuX

Crossed Swords Squire
Joined
Sep 19, 2018
Posts
179
Did you get another one and try again? Or a more reliable source? I would like a 161 as the pick 'n' mix function on the UniBios is great, or rather it would be.

Pick and Mix function ? What are you referring to ?

No I did not get another one - I bought a 138 in 1 which has more games and is supposedly more reliable (but it has the SUB PCB).
 

Tech&Music

Another Striker
Joined
May 14, 2016
Posts
325
Pick and Mix function ? What are you referring to ?

The latest Unibios version has the Pick 'n Mix feature, it has a nice built-in menu to quickly switch between games, switches games randomly when in attract mode, along with some other small improvements that enhance the 161-in-1 cart's usability. It's only compatible with 161-in-1, and an unsupported feature due to the finicky nature of these carts.
 

GadgetUK

Ace Ghost Pilot
Joined
Sep 27, 2013
Posts
1,323
I would fit 100nF capacitors in all the missing spots there, fit a heat sink to the regulator (or that will cause you issues), and get SMK dan diagnostic BIOS on there. I would guess you have a neo-buf fault maybe. I've got 7 of these boards here and no one board doesn't have multiple neo-buf faults. When they fail they tend to output when they shouldn't, and more often than not its intermittant.

EDIT: Oh, and get yourself a legit cart to test with - the 161 in 1 is not ideal to test with since the cart could be half your problem.
 
Joined
Oct 1, 2018
Posts
7
Brilliant. I'll order up those parts, keep looking for a cheap legit cart, and go look up what a neo-buf fault means.

Thanks everyone.
 
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