Nov 252017
 

I got this board for my collection as untested from an arcade operator

Board was the typical Konami pcb manufactured in Italy ( I believe Electronic Devices had a deal with them to import the pcbs and populate certain chips in Italy).

You regognize these boards because they have sound z80 made in Italy , soldered eproms and cheap sound potentiometer

Later on, beginning of 90s they started to put also general “E.Devices” stickers on eproms in place of Konami ones, but at least the eproms were socketed

Back to this board, it booted and the graphic was OK but there was a continuous metallic sound all the time.

Ruled out DAC and OP AMPS because usually when these fails, you have at least either FM or samples working, I started to probe the sound circuit logic following the schematics.

I noticed that the commands from the main CPU were correctly sent to the sound section but as soon as the Z80 had an INTERRUPT request, the CPU didn’t aknowledge it and blocked itself

In particular:

 

Signal IORQ didn’t go low, thus making the INT signal from the 74LS74 always LOW.

I proceeded to desolder the Z80 and tested it on another game with a socketed CPU and it confirmed to be bad.

While soldering the same Z80 by NEC used on proper Konami assembled boards, I also changed the sound potentiometer with an original Konami taken from another scrap game.

 

Game was fixed without any other issues.

Haunted Castle repair log #2

 PCB Repair Logs, Repair Logs  Comments Off on Haunted Castle repair log #2
Dec 282015
 

Got this pcb from a friend of mine for a repair

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The pcb had already all the sram chips repaired and some flying wires underneath because of broken traces.

Upon boot up, it constantly reset with this message:

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First thing was to test the socketed sram chip 6264 near the 2 big customs but as expected they were good.

Tried to flex the pcb and it booted with wrong palette sometimes

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Surprisingly once it booted it could be played with wrong palette all the time until the next boot.

So the code did only a check at the beginning.

After pressing and flexing everywere I found out that the game booted only when I pressed the Hybrid module 007327

I discovered looking underneath that the module has some small srams and looking at the schematics this is confirmed.

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I turned out that one pin had a subtle loose contact. I reflown brutally everything to make it more resistant against shocks.

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Booted the game and I was welcomed to a perfectly working game

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