MVS MVH-MV4 Board Issues A Plenty

So I bought a Neo cab on Tuesday with the above mentioned 4 slot board in it. The owner let me know that Slot 1 was not working, but if you skipped the slot the other 3 would be fine. He said if you installed anything in slot one you got a black screen.

Today I tried loading up the slots and found slot 3 was also shot-nothing, but a black screen, but only when I had the mobo entirely in the cab. If I pulled the board out of the cab the three slots worked well. I am guessing this is a short somewhere in the harness or the board is making contact in the metal cab.

Next I decided to see what is going on with slot 1. So with the mobo in the cab I install carts in all 4 slots and I got a Z80 error.

I pulled the mobo out and fired it up and all four games 'work' except now the sound is missing from slot 1 and 4 only. 2 and 3 were fine.

The previous owner mentioned he had swapped top board before and Slot 1 didn't work with the spare board either so I am guessing my problem lies in the bottom board. Any ideas on what I should check first?

Now with video http://www.youtube.com/watch?v=V4Emz800wg0&feature=youtu.be

UPDATE: I believe this is a combination of board (bad slot 1/no sound) and Monitor (blacking out).

I was told two things by the previous owner.

1. Slot 1 did not work and if you put a cart in slot one you would just get a black screen. However slots 2,3, and 4 worked flawlessly.

2. Anytime (and he stressed anytime) the cab is moved the RGB cable comes loose from the chassis and needs to be reattached.

Yesterday I fired up the cab a few times, got the screen image only to have it black out after a minute. You could still hear everything playing but the monitor was black. After getting paranoid that it was going into HV shutdown I removed the monitor, reseated everything and all was well again. I played for a good hour plus. Fast forward to today, swapping carts I get the black screen take the back door off to check for shutdown, but I have neck glow and I can hear the monitor running.

Get cranky, kick a puppy or two, and head to my office to grab an LCD to test it to see once and for all if this is a board or a monitor issue. Get home, remove the RGB harness from the chassis only to find the pins on the molex and the LCD are different sizes, cuss and scream and kick more puppies, reinstall the RGB fire up the cab and I have a picture. WTH?! Not only do I have a picture, but I played through 5 levels of spinmaster.

I don't know if I am grasping at straws, desperate to find out what is going on, but this is the third time that I have regained the screen image by taking off and reseating the RGB. The cabinet has not moved, there is no pressure on the harnesses so it's not like the harness has moved. Part of me wonders if this is what the previous owner experienced.

Has anyone else had any kind of issue like this before. It's just so inconsistent and until I can verify my boardset in another's cab or vice versa I feel lost.

Just as a heads up, 4 slot errors are numerous and can be a bit too much for beginner repairers. In this case (slots not working), you probably have bad traces in between the cart slots and logic chips, and/or logic chips to the bottom board (through the connectors). This thread covers the connections between the two boards, it might be of use to you.

http://www.neo-geo.com/forums/showt...ut-(a-contribution-to-the-crosshatch-problem)

Thanks!

For a 4 slot and 6 slot, always separate the boards and check for battery leakage by removing the battery and replace with a new one. If any traces are damaged then repair them. This is preventative maintence.

After that you will need to clean the slot really good using a cloth wrapped around and credit card with some contact cleaner. The abrasive effect cleans the pins VERY well.

Of course clean the carts with a pink eraser or I use a Staedler Mars as it works really well taking off dirt and then use a little contact cleaner on the cart edge and then try the cart.

If the problem still exists check to make sure there are no bent pins in the inter-board connects on the mobo. Make sure they are seated properly, after that you have to do advanced stuff if you still got the problems.

If you are just getting a black screen, it means it's reading the program rom but missing some data to start the game. So it could just be dirty.

What a strange problem especially the bit about the board working differently inside vs outside the cabinet. It sounds to me like your bottom board is fine, and your top board may (or may not) have some issues. The fact that you are getting a black screen is odd - usually I would expect the crosshatch. My first guess is that your power supply may not be up to the task or may be faulty. MV-4 boards can draw quite a bit of current so make sure your power supply is rated to give you at least 6 amps on the +5v line. Also like you said, the wiring may be bad. Do you have a multimeter?

Xian Xi said:

For a 4 slot and 6 slot, always separate the boards and check for battery leakage by removing the battery and replace with a new one. If any traces are damaged then repair them. This is preventative maintence.

After that you will need to clean the slot really good using a cloth wrapped around and credit card with some contact cleaner. The abrasive effect cleans the pins VERY well.

Of course clean the carts with a pink eraser or I use a Staedler Mars as it works really well taking off dirt and then use a little contact cleaner on the cart edge and then try the cart.

If the problem still exists check to make sure there are no bent pins in the inter-board connects on the mobo. Make sure they are seated properly, after that you have to do advanced stuff if you still got the problems.

If you are just getting a black screen, it means it's reading the program rom but missing some data to start the game. So it could just be dirty.

Click to expand...

Thanks! I just reassembled the board and then got a black screen in all four slots. Messed around with it for a bit and got them all working again minus the sound in slot 1. For whatever reason I can not get this MoBo to load consistently.

The previous owner only noted the black screen in slot one, but I have witnessed it in varying slots to all slots at the same time. Sometimes there is a sound accompanying the blackness other times there is not.

I got the Z80 error once upon boot, but have yet to see it again.

At one point all four slots were working, but it lacked sound in 1 and 4. Now all four slots are working, but there is no sound in slot 1.

This is my first neo multi slot, are they all this wonky?

Either the board connects are going bad or it's a TTL chip that's starting to go bad maybe.

Try checking channelmaniac's repair logs and see if you find anything related to your problem.

http://newlifegames.net/nlg/index.php?topic=152.0

One thing I forgot to mention is that MV-4 boards often require just a bit more voltage to get them to work properly. If your power supply has a voltage adjustment then try upping the voltage a bit at a time from 5.0 to 5.1 then 5.2... but don't go past about 5.5 volts and see if that makes any difference.

I wouldn't go past 5.2 since it has a lot of TTL chips that have a max of 5.25v.

mjs256 said:

One thing I forgot to mention is that MV-4 boards often require just a bit more voltage to get them to work properly. If your power supply has a voltage adjustment then try upping the voltage a bit at a time from 5.0 to 5.1 then 5.2... but don't go past about 5.5 volts and see if that makes any difference.

Click to expand...

Thanks guys, I just tested all of my volts and they were spot on. I may try a slight increase.

I just don't get it. Prior to my last post I got all of the games to load, came over to my computer updated my thread, went back to the machine turned it on and nothing again. Most recently it went black in the middle of a game select.

Here is a video I shot http://www.youtube.com/watch?v=V4Emz800wg0&feature=youtu.be

I am just baffled.

Check the bottom board and look at the quad chips to see if they have any lifted pins.

Edit: Just saw the video, it really might be your PSU is not able to keep up with the board.

Xian Xi said:

Check the bottom board and look at the quad chips to see if they have any lifted pins.

Click to expand...

I will give it a look now and report back. Thanks.

Updated my post.

Is it possible to test the volts on the MOBO? I have done it with plenty of Konami and Midway boards I just wasn't sure where to test on this guy.

It's not the volts, I think it's the current that isn't meeting the demands. You can try upping the voltage like mentioned first.

On the older 4 slots, when it's fully loaded it uses just under 6A on the +5v line. What specs are your PSU?

Xian Xi said:

It's not the volts, I think it's the current that isn't meeting the demands. You can try upping the voltage like mentioned first.

On the older 4 slots, when it's fully loaded it uses just under 6A on the +5v line. What specs are your PSU?

Click to expand...

I believe this is the original PS that came with the cab. It's an Elco MMC50-4

Specs:
+5 7 Amps
+12 1 Amp
-12 3 A

At this point I get a back screen regardless of the slot or number of carts.

I am not sure what could have changed between the seller's house and mine. He said aside from slot 1 the board never gave him any problems. When I first powered it on yesterday everything booted fine. When I went to swap carts I ended up with a black screen for slot 3, moved the carts around and it was fine.

I am hoping to track down a 4 slot board locally to test in the cab.

If that PSU has a Max continuous of 40 watts then that could be the problem.

Try doing this:

Only put 1 cart in but use the smallest meg game you have like around ~50megs or less and see if it plays fine, then add a 3rd low meg game and repeat until all 4 slots are filled with low meg games.

Then try it with the biggest meg games you have.

Xian Xi said:

If that PSU has a Max continuous of 40 watts then that could be the problem.

Try doing this:

Only put 1 cart in but use the smallest meg game you have like around ~50megs or less and see if it plays fine, then add a 3rd low meg game and repeat until all 4 slots are filled with low meg games.

Then try it with the biggest meg games you have.

Click to expand...

Right now I have 1 cart in the game and all I get is black. I turn it on with no carts and no crosshatch, just black.

Honestly I am just baffled. Hopefully someone local has a board they will let me use to test the cab.

Xian Xi said:

I wouldn't go past 5.2 since it has a lot of TTL chips that have a max of 5.25v.

Click to expand...

That's a good point. Most of the datasheets say that the recommended voltage range is 4.75 to 5.25 volts but that the absolute maximum rating is in the range of 5.5 to 7 volts. In practice I rarely need to go past 5.2 volts to get an MV4 to run properly, but I know someone who said he had to go as high as 5.8 volts to get his 6-slot to come on when fully loaded with carts.

Nerdygrrl said:

Right now I have 1 cart in the game and all I get is black. I turn it on with no carts and no crosshatch, just black.

Honestly I am just baffled. Hopefully someone local has a board they will let me use to test the cab.

Click to expand...

What happens if you remove the top board entirely and just connect the bottom board to the harness by itself? You should get the crosshatch screen. If you get crosshatch reliably with the top board removed but not when it is in place then the top board must have something to do with it (though that does not rule out the power supply because the top board draws extra power). If you still have trouble getting the crosshatch even with the top board removed then you know the problem is not related to the top board

I don't think it's the top board as the seller tried a diff top board and it resulted in the same 'black boot' with slot 1.

I will take it apart again and give it a go with just the bottom board.

Thanks everyone.

Ya, try just the bottom board. If it's still just black it's of course something on the bottom board.

Plugged in the bottom board-no crosshatch. Reattached top board-plugged it in crosshatch. Installed games-thumbs up (for now) minus sound in slot 1. I think this board is shot.

I am hoping to borrow a board locally to test in the cab. I am starting to regret the purchase of this beauty.

and now a beer or two before working on my Joust boards. What a way to spend the afternoon.

Use just the bottom board and try tapping the chips and see if anything happens on screen. Also did you check the battery if there is leakage?

HeavyMachineGun said:

Just as a heads up, 4 slot errors are numerous and can be a bit too much for beginner repairers. In this case (slots not working), you probably have bad traces in between the cart slots and logic chips, and/or logic chips to the bottom board (through the connectors). This thread covers the connections between the two boards, it might be of use to you.

http://www.neo-geo.com/forums/showt...ut-(a-contribution-to-the-crosshatch-problem)

Click to expand...

It's important to note that the link above is for (one of?) the model(s) that has 4 connectors between the boards. That being said, it was an immense help when repairing my 4-slot.

Mine had a few bad traces on the motherboard PCB. Two were repaired by the previous owner, and I repaired one after it mysteriously went bad one day. I suspect they all failed at the vias between layers of the PCB. Prior to repairing that last bad trace, the unit had been acting a little wonky. I didn't pay much attention to it because it was behaving kind of like the old NES toaster. I grew up with one of those, so I was used to it. However, after repairing the last trace, my unit has begun working perfectly. I've had absolutely no problems over the past couple weeks since I fixed it.

I'm no expert on Neo Geo repair, but I've dealt with many PCBs that are faulty like this in my line of work. If it's an on-and-off failure, it might be the board. At least, that might be part of the problem.

From what I've read, sometimes the trace problems manifest themselves out of a leaking battery or other similar damage. Other times, they just go bad because the PCB was faulty to begin with. That's what happened to me. My PCB never had any battery leakage issues.