Biomechanical Toy (Gaelco) - Graphic issues

[Nebula]

Hi forum!

I've recently adquire a pack of old PCBs and my surprise when I noticed that one of them is a Spanish (proudly! ) Gaelco classic: Biomechanical Toy:


It seems that this is the /2 revision (with encrypted ram???) and looks original with factory stickers in roms. It also has a small bridge next to jamma edge between button 3 and coin switch input... strange but seems to be some kind of small hack to insert coins with button 3....

Anyway, I plugged to my supergun tester and quick noticed that there are some problem in image:





Here are some small videos I did to show clearly the problem:
In the first video you can see how there is a kind of bars when the screen flashes
https://i.imgur.com/TxZHGdU.mp4

In the second video you can see the problem in video more detailed while demostration:
https://i.imgur.com/b7IDevq.mp4

It seems some kind of problem on analog video output, because there are no glitches in sprites or backgrounds, it's a general issue in whole image.

One more picture:




What could be the problem? Can you guide me from where to start to check the board?
I would like to keep this board in perfect working since it is a classic arcade developed in my country!

Thanks in advance!

[zak]

Congratulations on acquiring a rare and awesome game!

I have the game too, but it also developed a similar graphics fault at first. It then developed jailbars across the whole screen.

I've got someone looking at it at the moment. If they are successful with a fix, I will report back here.

FYI, that wire on the JAMMA edge is factory (they all have this) - it maps button 3 and start together - I'm not sure why they did this.

[Sp33dFr34k]

That button 3 thing is from the factory, are you sure? They could've made a trace for that when designing the pcb. Seems very sloppy... but yeah, very nice PCB, I only own the Squash game from Gaelco..

[zak]

That button 3 thing is from the factory, are you sure? They could've made a trace for that when designing the pcb. Seems very sloppy... but yeah, very nice PCB, I only own the Squash game from Gaelco..

I've seen 6 Biomechanical pcbs, they all have that wire on the JAMMA edge.

[Nebula]

Congratulations on acquiring a rare and awesome game!

I have the game too, but it also developed a similar graphics fault at first. It then developed jailbars across the whole screen.

I've got someone looking at it at the moment. If they are successful with a fix, I will report back here.

FYI, that wire on the JAMMA edge is factory (they all have this) - it maps button 3 and start together - I'm not sure why they did this.

Thanks for your response! About graphic issue, I only notice jail bars on those flashes on title screen. I also noticed that next to roms 16 and 18, some chips (rams?) were a bit heated. I don’t know if this is a normal behavior...

Let me know when your board were fixed and what’s the cause of that, if is successful fixed.

About bridge, my plan was remove it, but fortunately you adviced me that is factory-made, so I will maintain it

[Nebula]

Finally I bump this thread to post that I repaired the board!

Culprit of color/graphic issues was TTL: 74HC273 that latch pallette ram bits to analogic signal to jamma edge:





By the moment, new 273 is piggybacked over old one. I will desolder it soon and place new one.

And here is a small video of board working fine:



Finally this awesome "Spanish-made" "run'n'gun" game is fully working

[zak]

Congratulations on the fix! Make sure you socket that TTL though

This "Spanish-made" game puts alot of Japanese games to shame.

You can tell that these guys put a lot of love into this game.

There are 2 versions of this game. Each one has different music.

One of them is also locked to 30fps, whereas the other version jumps between 30-60fps.

I hope you enjoy the game. It's a very easy 1cc