Mortal Kombat 2 PCB - No Video, but ROM test screen *ding* is heard

GTRetro87

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Mortal Kombat 2 PCB - No Video, but ROM test screen *ding* is heard

Hey all,

Ok so, I had bought my MK2 board over 6 months ago, had it for a while and then decided to sell it cause I wanted to build myself a Hyperspin/Mame Machine and only keep a few original PCB's (X-men obviously lol). This game *was* 100% perfect with no scratches, etc, working perfectly sounding perfectly.


So the buyer had received it, way overseas, and the video wasn't working. He would hear the first *ding* and that's it, no video, nothing. I decided to purchase it back by refunding and just keeping the game (regretted selling it).


Now I have the game back. I looked all over the PCB and I noticed a couple pins bent (which I've straightened), a couple traces even had a very small scratch that I noticed (which I have to test and repair if needed).

I'm going to straight up blame the customs and whoever IN customs for tampering with the board when it was received overseas. I had included a kick harness meant for this game and the buyer didn't even receive that, so I'm more than sure there was a serious human error in customs..



Anyway, I noticed the same symptoms -- ROM check screen ding, and that's it. No video. However there is one thing - the LED's are both lit up, but one of the LED's (one furthest from the jamma edge) blinks every 2 seconds like it's resetting. I remember both LED's blinking when the game is working.

The sound board LED is lit up. That's about it, oh and I forgot to mention that when I boot the game - if I have the ribbon cable connected from the sound board to the PCB (the power cable is connected) -- you do NOT hear the ROM screen ding. Only when it is disconnected do you hear it



This is the best description I can give - I will make a youtube video showing what I'm describing. If anybody has any idea of what the issue could be (should the trace "damage" not be the problem), please provide input.


So far everything else looks pretty good, so I'm a little stumped
 
My MK2 sound board does that if one end of the ribbon cable is connected backwards. You'll hear the Bootup sound, but no in game sounds at all.

Also, I can make mine reset like that with only the boot up BONG sound if I turn the power adjustment knob all the way up or down on the switching power supply.

Sounds like its a voltage thing like that since the game is resetting and the MK boards are kind of picky about the voltage. It will reboot over and over if its too high or too low. I just turned it until it stopped resetting and went on to fully boot up.
 
Definitely not a voltage issue, I've been through that when I first got my first Midway game - this one actually. If it were a voltage issue only, then I'd at least get a picture - but the problem isn't that unfortunately :\

I forgot how the cable is supposed to be oriented, but I've tried four different ways - same results.


Video is the main problem. Perhaps the sync is shot?
 
If the revision roms are bad, the game will do nothing like you are describing. Same thing for UE13. If it is damaged or has bad legs/traces, the board can seem dead. My money's on an issue with the revision roms. Remove them and check the legs for corrosion or any kind of damage.
 
The sound board LED is lit up. That's about it, oh and I forgot to mention that when I boot the game - if I have the ribbon cable connected from the sound board to the PCB (the power cable is connected) -- you do NOT hear the ROM screen ding. Only when it is disconnected do you hear it

the tone is just the sound board saying "hey, I'm on". Qbert I observed even does the same thing even if the CPU board doesn't come up. :p I suspect it won't BONG when the cable's plugged into a dead board because it's trying to talk and there's nothing to talk to.

I doubt the program roms would magically get erased or die in customs, I suspect some other foul play possibly with UE13 like zeno described. if the board didn't have the plastic feet on it you're probably looking at any number of pins touching underneath too; those feet are vital.

zeno has some pretty good advice, I would start there. I had some cocked up program roms in my MK2 years ago and the game would still load but it would play baby crying sounds.

alternatively, there's a shit ton of T-unit boards suddenly dying like this. I have 2 NBA Jam boards that are completely dead just like you describe from mere rom swapping.
 
Hi there,

I was the buyer in this case. I got the board (sans kick harness), plugged it in, turned it on and got exactly what's been described by the OP. Took it to my local tech, same result. I didn't try any physical fixes or reseatings. What is odd is that I heard the ding no matter how the sound board was connected.

If it helps, here's a video of it at the tech's place:

 
Thank you for your input! That is interesting with the sound, I left the ribbon cable alone on the sound board side in which it came but switched it around on the main PCB side; don't really think it makes a difference but it was interesting with the *ding* working without the cable connected.

My next move is to reflow all the pins, check continuity on the traces that looked damaged and then possibly reseat the PLCC chips and the ROMs. Not into the logic part of repairs so I'll have to contact channelmaniac if it comes down to that.
 
Thanks zenomorph and mecha too, I'll definitely check the Roms too ASAP, esp U13. I'll see if any of them were pulled/damaged.
 
Thank you for your input! That is interesting with the sound, I left the ribbon cable alone on the sound board side in which it came but switched it around on the main PCB side; don't really think it makes a difference but it was interesting with the *ding* working without the cable connected.

My next move is to reflow all the pins, check continuity on the traces that looked damaged and then possibly reseat the PLCC chips and the ROMs. Not into the logic part of repairs so I'll have to contact channelmaniac if it comes down to that.

take a look over the CPU too. the scaler chip is nearest the JAMMA edge, the Custom Chip UE13 in the middle, and the CPU (with the TMS markings) is on the other side.
 
Currently reflowing solder around U13, didn't have a very small bevel tip so I figured to remove one of the diodes or caps (looks like a diode) surround it to make extra space. Broke one lol

What's the replacement part for this? I see "103 MES" or ME5? The locations is C204
 
Found the part - C204 = .1uF Capacitor

Ended up drag soldering the remainder of the U13 chip, so far there were no loose pins but all is clean now - just waiting for the capacitor I just ordered to replace the one I broke; let's see what happens.

I did happen to pull the revision roms but there was no noticeable corrosion or damage.
 
still waiting on the 0.1uf capacitors ordered, however I had a 0.1uf ceramic disk cap that I thought I'd just try.. still nothing.

U13 is all reflowed, I tapped on the PLCC's lightly, nothing.. I even hit the little white Reset button which caused one LED to stay lit while the other (that blinks every 2 seconds) to turn off (obviously turning back on when released) -- nothing

The traces which I first thought could have been damaged, I tested them, continuity is great. Right now I'm really confused as to what could be the problem

If it truly is a revision roms, then I'm going to need a GQ4X to test the eproms and reburn or burn new ones.

One thing I did notice, both UE9 (sticker A-16217) and UF17 (sticker - A-17748) are much warmer than the rest of the board. They're not hot, but noticeably warmer - not sure if they supposed to be this way or not


Anybody have any ideas??
 
You're left at a stopping point until you can test the ROMs.
 
Channelmaniac: yea, I might as well get the GQ4X already and start doing Rom work (could fix my CPS2 while I'm at it).

TheEnglishTear: most definitely is a PCB issue, never said it was monitor (if it were then it'd be obvious because of the refresh rate). I'm not sure how at all because before I sold it, it was working 100% and had the hardest time trying to beat it. Thought to sell it, was received by the buyer as not working.. then bought it back and received it (same exact PCB according to picture, stickers/placements, etc).


So, I still haven't pulled the PLCC's but I believe I have an extractor somewhere in my house; not the spring loaded but it's still an IC extractor. And like said earlier in the post, I need a GQ4X to test the Rom's
 
I only ask because you didn't mention it, and I've had issues myself where monitors become jarred in trasnportation, wires become loosened, etc. and if it's a polo monitor like mine, it's really finicky.
 
Ohhhhh ok I gotcha. Nah it wasn't a monitor issue at all, I mainly use my home built supergun with a JVC I'Arte CRT that works with everything I throw at it, but even on my cab (which I figured to test just for the heck of it - 25" K7000) it's the same issue.

You have to see the video on the first page of this thread, that's the exact symptom I've been getting.
 
honestly, this is becoming a common issue with the T-unit hardware. something goes bad on them and I don't know what. I've mostly seen it on NBA Jam (not TE), but they're all the same.
 
It seems that way mecha all the post i have read about T units seem to be all the same type of issue seems like they are coming to that age where things start to stop working for no reason like CPS hardware customs :(
 
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