Jun 122018
 

Recently I have been working on reproducing the MB112S146 custom chip for my friend BanjoGuyOllie.
This module is found on Arkanoid, Darius and probably some other titles too.
This has now been done and is available in the downloads section. It required the adapter board from ColinD but I will soon compile for MikeJ’s module too.
So far its only tested on Arkanoid but probably will never get a chance to test on other hardware.

 Posted by at 7:39 pm
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
http://www.jammarcade.net/wiki

 Posted by at 9:18 am
Jun 102018
 

This is a simple reproduction I made of the joystick sub board you can find on Cabal PCBs.

I kept the original design of the original sub board which is this:

With the only difference I put the 74LS244 on top of PCB:

The reproduction is something not really great perhaps, someone else already made it it the past like Elgen:

http://elgensrepairs.blogspot.com/2013/04/tad-cabal-trackball-to-joystick.html

But it’s useful if you want to convert a Cabal PCB from trackball to joystick version using at same time the proper ROM set.

That’s all, simple but effective!

 Posted by at 9:17 am
Jun 082018
 

The ‘HB-45A’ is a custom IC used on some PCBs manufactured by Seibu like Raiden II/DX and SPI motherboard.It can be considered  an evolution of the ‘HB-41’ that we already treated in a past article:

Seibu ‘HB-41’ reproduction

It shares the same 20 pin SIL package embedding most of the analog sound system.Its function is to mix and pre-amplify both music and sound FXs :

Here’s how it look “naked” of its external coating:

Design is almost identical to its predecessor with the presence of two OP-AMPs (a dual and a quad one) although they operate from a single supply (+12V)  and not dual (+5V/-5V) like the ‘HB-41’.All other components are ceramic/tantalum capacitors and resistors (surface mounted and printed film ones) which are part of the application circuit of the two OP-AMPs

It took some time to draw schematics not without some difficulty due the presence of some hidden printed film resistors located under the quad OP-AMP:

Schematics were then routed to a PCB which looked pretty good on a 3D preview :

The real thing assembled in all its parts :

For a while I was not able to test this reproduction due the lack of a working PCB (the “decapped” original part was taken from a dead board) until the user ‘opt2not’ from Arcade Projects and KLOV forums kindly volunteered.The test platform was his working Raiden DX PCB.He first removed the original ‘HB-45A’  in a very clean way (he used an Hakko FR-300 desoldering gun)

Installed some female 2.54mm round machined headers:

Lastly the reproduction fitted onto the board:

Then he made recordings of audio of both original custom and reproduction redirecting it to a PC from a HAS supergun using a SPDIF breakout from the  SCART connection.

Here ‘s capture using the original HB-45A:

 

Here’s the one using my reproduction:

 

Comparing the music and FXs at the beginning and end of the recordings sound identical.No differences in quality can be noticed (the slight background noise is normal when there is silence).

For this successful reproduction project I would like to thank again ‘opt2not’ for his precious testing and all material (pictures and audio captures) he provided me.I recommend you to check out his blog :

http://the-artcade.blogspot.com/

 Posted by at 9:10 pm
Jun 042018
 

Was asked by a friend to repair his Sunset Riders.

When starting up the PCB, it was stuck in something resembling a watchdog fault.

But I’ve been working on Sunset Riders before and this didn’t seem like an ordinary watchdog. I felt that it went a little bit longer in the startup sequence before crashing.

The board was a bit dirty but I started with the usual:

  • Checking CPU signals like clock, reset and halt
  • Verifying the program ROMs
  • Checking the program RAM for odd signals

All looked ok, but then I found this at the 051550 reset signal generator.

Pin 1 on the 051550 looked like a cold solder joint.

Pin 1 is the clock signal input pin on this IC and without that input, I can understand that the game doesn’t boot up properly. Gave that pin a dab of solder

And booted up the game

Board fixed without any other issues 🙂