Mortal Kombat II woes...

shardian

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I have an MK2 that is gonna be the death of me. I have 3 boardsets. I'll give the basic rundown of all three.

board 1 - just plain dead. *No memory expansion board

board 2 - Fires up to the test screen, but finds a pile of bad roms on UG and UJ sides - always mated pairs. **Has expansion board

board 3 - Got this as working from another member here, but he was having PSU problems. Nope, he was having CPU problems. The game boots fine most of the time and will play a round or two. Then it craps out and might reboot. Sometimes it doesn't work at all. Adjusting +5 really doesn't do much. The bottom LED (DS3) sometimes flickers or goes all the way out. What exactly does this LED mean? Having sound board attached has no effect. I wasn't getting it to boot at all, then pulled the battery and it booted, but would still crash every minute or two. This board also is very dirty with bent headers and gunk in the little square cpu's.*** No expansion board, and all the video roms are soldered to board...

I have 3 sound boards. One does nothing except for some mild speaker whining, one emits an unholy loud squeal after the 'bong', and the third works fine.

I tried to swap out all the roms from board 1 into board 2, but then it showed every single rom as bad. I tried with and without the expansion board. I've heard people mention a jumper for the expansion board, but I've never seen it mentioned in the manuals and can't find it on the board itself. Can someone kindly point it out to me.

Also, where is a good place to measure +5 at the board? Was it too much to ask Midway to supply test points?

Any help would be appreciated. If there is someone who works on these boards, please point me in that direction. I just want a working dag gone board!!!
 
I have an MK2 that is gonna be the death of me. I have 3 boardsets. I'll give the basic rundown of all three.

board 1 - just plain dead. *No memory expansion board

board 2 - Fires up to the test screen, but finds a pile of bad roms on UG and UJ sides - always mated pairs. **Has expansion board

board 3 - Got this as working from another member here, but he was having PSU problems. Nope, he was having CPU problems. The game boots fine most of the time and will play a round or two. Then it craps out and might reboot. Sometimes it doesn't work at all. Adjusting +5 really doesn't do much. The bottom LED (DS3) sometimes flickers or goes all the way out. What exactly does this LED mean? Having sound board attached has no effect. I wasn't getting it to boot at all, then pulled the battery and it booted, but would still crash every minute or two. This board also is very dirty with bent headers and gunk in the little square cpu's.*** No expansion board, and all the video roms are soldered to board...

I have 3 sound boards. One does nothing except for some mild speaker whining, one emits an unholy loud squeal after the 'bong', and the third works fine.

I tried to swap out all the roms from board 1 into board 2, but then it showed every single rom as bad. I tried with and without the expansion board. I've heard people mention a jumper for the expansion board, but I've never seen it mentioned in the manuals and can't find it on the board itself. Can someone kindly point it out to me.

Also, where is a good place to measure +5 at the board? Was it too much to ask Midway to supply test points?

Any help would be appreciated. If there is someone who works on these boards, please point me in that direction. I just want a working dag gone board!!!

well, I can't speak for your boards, living or dead, but there's a couple things I can probably help you with.

the LED, I can't remember what it did, I thought it had something to do with when sounds play though, if that makes sense.

good test point for +5 is probably any IC on the board, like a rom or whatever. I can't remember for the life of me though which pins you meter to test for this, probably google it if you can, but that's the most accurate way to do it, cause that's actually what you're powering with the +5. otherwise what I do is meter at the PSU first, and when it comes to the over/under, I adjust that for the "under" first (say 5.05-5.10), then I meter at the JAMMA harness. MK2 I figure since you're powering the sound board off the main board would probably command between 5.15-5.20... but like I said, meter at one of the ICs. the sound board should really only need the +12 though, but then again I guess you're running roms off it too, so do a voltage check at one of the roms on there too. don't worry if the +12 comes out at like 13V or higher or the -5 comes in at like 4-ishV.

the memory expansion setting is actually accessed via dipswitch. it's under dipswitch bank UJ1 at switch 8. set to On = 1 board (no expansion) and Off = 2 boards (expansion board).

mysteriously, in MAME, you can set it to either or and the game will work fine. for all intents and purposes though, the memory expansion arrangement used 4 mb roms, while the "newer" design that eliminates the need for the memory expansion had 8 mb roms.

your board #3 may be fixable with some cleaning. speaking as someone with an MK2 board that's had nothing but intermittent troubles (I haven't even booted it in over a year either) I can tell you that it's the biggest pain in the ass of all the MK games to maintain.

the easiest thing to try though is reseating roms. I'm talking about going above and beyond just pressing them firmly into the sockets, however. I removed every single rom from my board and reinstalled them to fix the problem I had, and figured that was all that needed to be done until a few recent MK2 threads on here came up and that worked to no avail for them. another thing I completely neglected was the possibility of formation of corrosion on the pins for the roms -- I bought a DK last month that would lock up or not boot at all, and I wound up taking 200 grit sandpaper to the IC legs on every socketed component and guess what... it worked.

another user did this on their MK2 and sure enough, that was the missing link. if you ever wanted to I'm sure you can scalp some straight headers from one of the other boards by way of desoldering the pins. but I would definitely entertain doing the sandpaper method, especially if the chip legs have any dark appearance to them, and as for the CPU socket, well, I guess an old toothbrush soaked in alcohol can handle that. of course let the board/CPU dry thoroughly after doing this.

maybe with a little luck, you'll get a working board out of this. the T-unit was a fragile miserable piece of shit to begin with, far inferior to the Y-unit in terms of build quality. maybe it's because it doesn't have RAYMOND GAY's name on the side of it. ;)
 
Get yourself a PLCC chip pulling tool. Remove the square socketed chips using that and clean the gunk from the sockets then reinstall the chips.

Check the boards top & bottom for gouged traces. Those gouged traces are common issues on that boardset. They seemed to have fragile traces and ops are notorikous for throwing boards in boxes which causes damage to those traces.

Once all that is repaired, report back.

RJ
 
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