Lethal Enforcers Arcade Repair

Hey everyone! I've had a lethal enforcers arcade cabinet that needs some work sitting in my garage for a few years and I recently decided to mess with it and get it working. The game works, however there are jailbars in the graphics and there is no sound.



The light gun is accurate and the game plays fine apart from these two issues. So I went ahead and pulled the motherboard for inspection.



And from some research this chip here seems to be the culprit for the board not having sound.


Apparently these 054986A chips are notorious for their capacitors going out, leaking and damaging the traces. For whatever reason the manufacturer painted over all the traces and caps with black paint. I was reading all sorts of different methods for removing the black paint from old forum posts I found while searching the Internet. The one that seemed to be the least destructive was to use some paint thinner to remove the paint. So I used some Tamiya paint thinner I had laying around and also some 99.9% tech alchohol. The results were pretty decent:


Here's a nice schematic I found that someone created to help guide the repair



Another potential issue I discovered was some corrosion on two other chips.

The first is on two pins of the 054539 chip, which is also another sound chip. However, the two affected pins don't seem to be connected to anything. So I'm not sure if they're attributing to the sound issue, if anyone can find a data sheet please let me know.




The other chip is the 054157 which is one of two tilemap generators on the board.



After some clean up


Those four traces are all broken. I'm thinking these may be the culprit behind the jailbars. I must also mention that the jailbars are not visible on certain sprites, and also in the Testing menu the screen is clear.

Anyone ever repair these boards and can offer any tips? I'm going to try swapping the capacitors on the sound chip, but I don't really think I will attempt to repair those traces until I can get my hands on a soldering microscope.. the pitch is very tight and my eyesight is not so good lol

 

Interesting stuff! Take lots of pics and keep us updated on the repair. Maybe perhaps do a video of the repair. Electronics therapy and all that jazz

 

Looking like an easy fix, just solder a connecting cable to them vias and that should do it.

 

Yeah it's just very small and I'm hesitant to do it without some sort of microscope. I'm working on the sound fix first!

 

I re-capped the sound board and checked all the traces according to the above diagram. I now have sound, however its very low volume. I looked at some other pictures I've found online and tried a few different orientations (polarization) of the caps, and also different values (that i saw other people use) and it had no change. I'm thinking there may be some issues on the underside of the chip, which I've also read about happening. When this happens you need to harvest a new chip from another board, so in light of this, and to avoid spending hours on a lemon, I found another board on eBay for $30 that has perfect video, but of course sound issues. It's on its way here and I will attempt to fix the sound on it and hopefully have a working dedicated Lethal Enforcers game.