I got this board from my friend Joachim for a repair.A Nintendo Playchoice-10 system:

For the uninitiated, Playchoice-10 is the arcade hardware developed by Nintendo to run its most popular NES games inside an arcade cabinet.The games for this system are in the modular form of carts which are plugged into one of the ten open slots on the PlayChoice-10’s motherboard:

When I first powered it up, I was greeted by a solid black screen, no activity on main Z80 CPU.A closer inspection revealed a missing 8MHz crystal @X1 which supplies the clock to main CPU:

Once fitted a new crystal I had clock signal on pin 6 of the Z80 but the watchdog circuti was active ( /RESET line was constantly going to HIGH to LOW state in a endess loop).I pulled the Z80 and tried it in a good board having confirm it was faulty.With a good CPU all I got was a green screen:

While probing chips I came across a TMM2115 (6116 compatible) RAM @4K which was burning hot to the touch, I remove it and my programmer reported it as shorted:

With a good RAM I got always that green screen but could hear sound sign that the board was playing ‘blind’.This was a good chance to use my Fluke 9010A troubleshooter.MAME reported this memory map:

0000 – 3fff = Program ROM (8T)
8000 – 87ff = RAM (8V)
8800 – 8fff = RAM (8W)
9000 – 97ff = SRAM (8R – Videoram)

I could successully perform a RAM LONG test on address space of RAM @8V and 8W but I got an error on the videoram @8R (all these RAMs were 6116 compatible):

Once removed, the chip failed the out-of-circuit test:

Finally I got it running:

but, since the motherboard (PCH1-01-CPU) was a dual monitor type, I could not display the playfield (although it came with this JAMMA adapter which provides also outputs for a second arcade or VGA monitor)

 

I thought this repair was the perfect opportunity to show you how to correctly servicing the ‘infamous’ Konami ‘054986A’ custom audio module (obviously this is valid also for the ‘054544’ one).Follow this guide at your own risk.I’m not responsible for any kind of damage!

Let’s start.

I got from my friend ‘supermik’ this Mystic Warriors PCB:

Board played fine but had an orrible sound output, very loud and distorted:

Obviously the culprit was the ‘054986A’ module whose capacitors were replaced by thru-hole electrolityc ones:

But this was not enough to fix the issue.So, instead of troubleshooting the module (the 4558 OP-AMP and the AD1868R DAC undersneath were most likely bad), I opted for its complete replacement using a Premiere Soccer as donor board :

The removal of a module consists in the following steps:

Prepare the board by covering the solderside with some aluminium foil leaving exposed only the pins of the module:

Clamp an IC extractor on the sides of module:

Put the board wrapped in a cloth or pillow  between your legs:

Now, with an hot air rework station do a first preheating of a couple of minutes on the exposed solderside setting the temperature at 100 Celsius degrees.Then, set the station at 250 degrees for a minute or less:

In both cases, you have to move the hot air gun back and forth without stopping otherwise you could damage the board.

After done this preheating (needed to facilitate the solder melting and avoid heat stress) you have to use an heat gun for the last pass.Personally I use a 2000Watt model and set the temp to position ‘8’:

Keep moving the gun back and forth and at same time gently pull the IC extractor:

When the solder will arrive at the melting point, the module will come out easily from its seat:

Next step is the sockets installation, use 1.78mm pitch ones (cutting a single socket in half):

Lastly, mount your good module and you are set.

Ah, I forgot..board 100 fixed!