CK2605 Logic Diagram

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Nov 262018

While searching through some documents from Data I/O I came across a bunch of logic diagrams for various PLD’s. One of them was for the CK2605.
As I’ve not seen this in the wild before I thought I’d upload it.

*click the picture for PDF

 Posted by at 6:11 pm

Contra repair log

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Nov 042018

Received from USA this mint Contra PCB (by Konami), actually with japanese stickers and ROM set :

The board kept resetting in an endless loop sign that CPU was executing no valid code hence the watchdog circuit was triggered:

The two program ROMs were dumped as good so problem was elsewhere.Board was almost fully populated with Fuitsu TTLs which are well known to be prone to failure.When probing them with a logic probe I found a floating output (pin 11) of  a 74LS08 @17D:

This was confirmed also by logic analyzing and scope:

As schematics shows, the missing signal from pin 11 is called VRC and it should  be a control line routed to the custom ‘007452’ :

I removed the TLL and tested it out-of-circuit where it failed miserably :

I installed a socket and fitted a good IC:

The board booted into game with no further issue.Repair accomplished.

 Posted by at 6:05 pm
Nov 012018

Some time back I bruteforced the A-17480 PAL16L8 chip from Mortal Kombat II. This was untested until recently when UKVAC member JonHughes tested it and found it didn’t work properly.
We tried several things but always got the same issues so he sent me his full PCB to do some testing of my own.
While I could find anything wrong from an operation point of view I did find that the original TIBPAL16L8-10 PAL chip transitioned states about 4ns faster than the fastest GAL chip I have to hand. I had experimented with GAL’s ranging from 10 to 25ns but the slower ones did just make the issue worse.
In desperation I ordered a NOS TIBPAL16L8-10 from eBay (not too cheap these days) in order to be 100% sure of my work. The result was a perfectly running game.

So what are the issues? Well not a lot really. A GAL substitute will still allow the game to play very well but it did show errors during the POST

The game itself also plays fine but there are some graphical issues here and there, most noticeably on the ground during actual gameplay.
On the video you can see the ground keeps glitching black. This is pretty much the only fault I can see but its definitely worth noting

The video is not the best quality, capturing CRT screens with my phone is never great but hopefully you can see.

 Posted by at 4:50 pm

Decrypted SEGA files removed!

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Oct 272018

Due to certain things that have been going on elsewhere on the internet I have made the decision to remove the SEGA ROM’s from this site.
I have not personally been asked to take these down but given what I’ve seen happen recently involving SEGA ROM’s and previously with Nintendo too I thought I would play it safe and remove these files.

Sorry for any inconvenience

 Posted by at 7:38 am

PLD Archive news

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Jun 102018

The PLD Archive is currently in the process of being moved to a new wiki.
There may be a delay is adding new files while the wiki get populated. This is currently over half way done but the process is long and tedious bear with us.
In addition to the normal PLD files there is also scope to add more detail and pictures so if anyone has any good quality PCB pictures or extra information like missing PLD IC location details or names then please let us know.

The old table will be kept up for now until we are sure all the detail has been moved over correctly.
You can take a look at the wiki at

 Posted by at 9:18 am