Neo Neo mv-4 issues

thebman80

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I have a 4 slot MVS that has a strange issue every time turn it on the 2nd player credits itself 1 credit. There is also in issue with horizontal lines through the games in every slot. Just broke down every cart I have and cleaned the crap out of them tonight and the issues with the horizontal lines didn't change. Once in a while the sound will cut out but that's maybe like 2% of the time. I also just installed a new memory battery doesn't seem to be that much corrosion damage. 3 resistors near the battery looked like they where touched slightly already replaced one but not the other 2.

Hopefully I will get 10 min tomorrow to check the voltages. Some of these issues seem more than just low voltage issues but I have been wrong before.
 
Ok so got my meter into the cabinet and the 12v lines were weak at best one side barely registering. 5v seemed good but all this testing was done without a load on the line. So I guess I'm rebuilding the power supply first chance I get. Doesn't seem like this weekend is going to yield any time maybe Monday night and I will give an update. Its going to be such a bitch getting that PS out of the cabinet my MVS is in the corner with Marble madness 2ft in front of it LOL. Guess If I have it out its time to recap the monitor.:rolleyes:
 
Hey, i had this same exact problem on my MV2 for like one day. The thing was crediting itself, or even weirder, it would cost 13 credits to play one game (the credit list said 13 but you couldnt start a game!).

I just pulled the pcb, gave it a solid cleaning on the edge connector and took off the cover, cleaned it all out, reset connections etc etc. Has worked ok since, but yet, strange stange issue.
 
Yeah when it credits up then number 20 appears on the credit display and then it clicks and one credit is on the 2nd player. Once I get back to work on my games I'm going to try cleaning the slots and edge connector as well. The carts are as clean as there going to get no issues there. Also going to have to try to rebuild the power supply since the 12v is out of whack I think that might be the cause of the credit issue.
 
Reset the backup RAM.

Won't fix lines on the screen but will help with many credit issues.
 
Take all the carts out... press p1 start until you get to the screen for resetting the backup RAM
 
I believe I did it right well it stopped displaying the 20 in the right display but pops one credit up still. I just went to check out my 2 slot board I had stored and that is not working now has the oh so pleasant click of death and a scrabbled screen.
 
Ok I did a little poking around with my 2 slot and my 4 slot MVS boards, here is what I came up with. 2 slot click of death went and popped out Bios chip and swapped it with the known good one and the clicking stopped. Put the 2 slot Bios into the 4 slot and the 4 slot board had the click of death so Bios is bad on the 2 slot. Now The screen is scrambled and no clicking but If I turn it on and off once or twice I get Video RAM errors on the 2 slot board one of the errors said Address write read 000022b3 5555 it would keep changing error codes as I turned it on and off. So I guess the vid RAM might be bad. I do Have a logic probe just unsure as to how to test the chip pulsing.(I just got the thing haven't learned to use it yet).

Now On the 4 slot top board I noticed some chips with corroded legs some where minor 3 where nasty. HD74LS244P Locations P2 (really bad), D3 (minor), E6 (minor), D6 (minor), K2 (Really Bad). HD74LS245P 5D (Really Bad). Might these be in charge of any Vid Signals on the board? I guess its a good as any place to start if there not bad they will be soon enough.
 
Just out of curiosity I have a ROM burner and I already have several Bios chips made with the ultimate Bios with all the cheats ECT. But I just want the Regular Bios right now In my MVS upright I have the Neogeo Zip but What Image do I use off it? I heard the European is the best for the MVS so what file image is that sp-e.sp1? Or some other one?
 
Well just got my chips today and only had time to do one chip. Replaced the HD74LS245P chip that was really bad and cleaned the edge connector of the PCB. The credit problem where the game coined itself up is now gone and the lines are a little less through the graphics. Still much more to do when I get more time maybe I can do more Monday night.
 
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