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Terra Cresta bootleg PAL dumps verified and redumped

PAL Updates Comments Off

Jun 042017

Having a working Terra Cresta bootleg (from Tecfri but they are all the same) gave me the opportunity to verify the PAL dumps we had.I successfully converted from PAL16R4 to GAL16V8 fuse map two of them.The third one was a native dump from a PAL16L8, the fuse map we had was not good so I redumped the device from my board and successfully reversed it in GAL16V8.Most likely, like it often happen for bootlegs that have same layout of original, the dumps should be working also on the Nichibutsu board but a real test is needed and would be appreciated.

Money Money PAL dumps added

PAL Updates Comments Off

Jun 032017

Some days ago I dumped the PALs from a pretty rare board : Money Money by the italian Zaccaria manufacturer.Here’s how board looks like:

Devices were three secured PAL16L8.I reversed two of them in a GAL16V8 while I was able to fit equations of the third one in a GAL22V10 (so tie pin 10 to pin 12 of the IC when installing the replacement in a socket).

Defender repair log #1

General, PCB Repair Logs 1 Response »

May 252017

I got for my collection an untested boardset of Defender which was really in great conditions with no battery acid leak.

The boardset is the newer revision of Defender with the red label roms.

The game is very difficult to find it in working conditions nowadays because it has several weak points, expecially the 24 drams 4116 which are very unreliable to due the fact the run very hot and they require +5V, -5V and +12V to be applied at the same time, otherwise they will be damaged.

The old Williams PSU become defective and often they ruin the drams.

After converting it to Jamma and triple checked all the power supply lines I booted it up but the game appeared to be dead.

Fortunately Defender has a lot of bibliography and a very good manual which is also a troubleshooting guide.

I check the clock and it was working correctly, but after checking the reset line I saw it was pulled low all the time.

To make it short, Defender has two +12V power supplies, one regulated and one not.

You have to supply +12V also to the not regulated one because it is needed for the power on reset.

After adding that +12V t, the game booted but as soon as the message ALL UNIT OK was displayed it reset in a never ending loop.

I found out that the problem was caused by the ribbon cable , after reseating it a couple of times, the game booted correctly.

I started the game but the ship kept always going down.

With the test menu , it reported that the down direction was always pushed.

I checked the interface board which has the circuit for the inputs. the hex inverters 4049 were all toggling correctly, the pull up resistors were good therefore there was only one chip to check: the Peripheral Interface adapter 6821P.

I desoldered it and installed another one I had on stock taken from another arcade games.

Since I had no way to test it, I decided to put a 40 pin socket just to be sure I could easily swap it with another one in case it was defective.

Luckily the inputs were now correct, thefore I could declare the board fixed.

In the end I was very lucky because the game had only the input problem and no other issues.

Rastan repair log #5

PCB Repair Logs, Repair Logs Comments Off

May 252017

The game had some missing background tiles

At first I thought it was a maskrom problem but once I checked all of them only to find they were good, I started to probe the ram responsible for the background.

A sram @IC31 had some weak data signals so I decided to change it and the guess was right because the game was fixed.

Michael Jackson’s MoonWalker repair log #1

PCB Repair Logs Comments Off

May 212017

Another board from the recent operator raid, an original Michael Jackson’s MoonWalker (on Sega System 18 hardware)

Despite its age and the use of the FD1094 CPU module with battery backed-up RAM the board was still working except for the sound samples (drums, speeches, etc..), they were missing or replaced by random ones:

The hardware uses a rebranded Ricoh RF5C68 as PCM sound chip :

Not able to find any datasheet I went to “listen” its pins with an audio probe.When I hit the analog outputs (the IC has an on-board DAC) I realized that sound came already wrong out of it.So the chip was the only responsible and it needed to be replaced:

Done and…success!Board completely fixed.

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