jamma interface IC

ttooddddyy

ttooddddyy

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Anyone got one of these sitting around on a faulty board (as you can see some of the pins have broken off this device), its a jamma interface IC, sits near the edge connect like one of those flatpack hybrid ICs you see on some boards, dont have the actual board with me at the moment.

jammaIC.jpg
 
ttooddddyy

ttooddddyy

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Im not sure, I dont have the board with me at the moment (its at the workshop and Im at home), but I know its not a bootleg, I think its a Toaplan but not certain, will post a piccy of the board tomorrow. I have checked the images of Toaplan boards that I have links to, and can not see that device being used.
The board boots with a "tilt" error message ?
 
ttooddddyy

ttooddddyy

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I think its Truxton 2, I dont see any of the other Toaplan boards using this device, so my chances are slim, I was hoping to solder jumpers from the IC but the ceramic track carrier is broken too close to the casing, maybe able to dig in :( otherwise I think the board is OK. I have a good working Truxton, to get a #2 to go with it would be awesome.(Truxton #1 doesnt use this, its 4 years earlier)

toaplan.jpg
 
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Reznor007

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Well, it's definitely Truxton 2...but I couldn't find even a mention of that IC anywhere.

Maybe you could try grounding JAMMA pin S(tilt switch) and see if the game boots...that IC could just be a inverter, and the game normally thinks grounded is unpressed/ungrounded=pressed...so without the inverter it would be thinking the tilt was always pressed. Just a random thought though...
 
ttooddddyy

ttooddddyy

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I get your point Rez, trouble is the input to the Jamma interface/inverter IC is broken (pin S is now open circuit), so i need to know the tilt output pin of the device, so that I can change its logic state. Anyone know where I might find a Truxton 2 schematic ? It will be the same of course with the other inputs, but I could work around that with a schem.
 
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ttooddddyy

ttooddddyy

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I managed to bust the device open, held the bottom cover in a vice and used a hammer and chisle to brake open the top cover of the chip, the cover came off in one piece :) it ripped out a couple of surface mount capacitors on the way, but thats not a problem.

bustedopen.JPG


Now the tricky part is to remove the bottom cover without smashing the ceramic board sandwiched in the middle. Hell I have nothing to loose :spock:
I think I may be able to pull this off guys :smirk:
 
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Reznor007

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I can't tell from the picture...but is the circuit basically a signal inverter like I assumed it was? I checked MAME and it says those games have high inputs...so that kind of agrees with me.
 
ttooddddyy

ttooddddyy

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Reznor007 said:
I can't tell from the picture...but is the circuit basically a signal inverter like I assumed it was? I checked MAME and it says those games have high inputs...so that kind of agrees with me.
Click to expand...

Yes its an inverter and buffer array, there are a couple of smd ICs on the other side as well, I managed to get the bottom cover off but broke the ceramic board into three pieces and ripped off one of the smd ICs :( in the process . The case material is the same as standard 27C eprom cases (real tough, tried to grind it but just got sparks) and bonded to the ceramic board . I still reckon this can be fixed. Its become a real challenge.
 
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Nightmare Tony

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what are the numbers on the chips inside?If merely inverted, you can play make your own chip.

try drawing out the diagram, all the inputs from the JAMMA edge to that chip. The other pins will be power and outputs, you can trace those. The outputs should go into 74LS245s, 240s or 244s. The custom at the far end appears to be graphics, so methinks the inputs are running into TTLS, prolly the 20 pin ones alongside the dipswitches.

Basically, make an input RRC, a pullup 1K, a series 220 ohm and a 0.1 cap to ground. That goes for each invereter input, for each JAMMA input line. THEN the trick is to find out where they come OUT to....

Difficult but not impossible....


Good luck.
 
ttooddddyy

ttooddddyy

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Nightmare Tony said:
what are the numbers on the chips inside?If merely inverted, you can play make your own chip.

try drawing out the diagram, all the inputs from the JAMMA edge to that chip. The other pins will be power and outputs, you can trace those. The outputs should go into 74LS245s, 240s or 244s. The custom at the far end appears to be graphics, so methinks the inputs are running into TTLS, prolly the 20 pin ones alongside the dipswitches.

Basically, make an input RRC, a pullup 1K, a series 220 ohm and a 0.1 cap to ground. That goes for each invereter input, for each JAMMA input line. THEN the trick is to find out where they come OUT to....

Difficult but not impossible....


Good luck.
Click to expand...

Yes they are LS240s, I think I maybe able to patch the board, but its like micro surgery. Otherwise I will try to build a device as you suggest.

BTW good to have you call in again Nightmare, havent seen you around for a while :)
 
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Nightmare Tony

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I've had some login problems for some reason. Nallchan worked hard to help get me going again. its been kind of wild, buying up amusement park rides out here :)



The 74LS240 is a gated buffer, which I had metioned that it would feed directly into. That means that the deata bus is going to connect to several pins for the custom. Whgen you make your diagram of the pinout, some pins will be data bus based, those are where the outputs of the 240s go. So at this point, you can literally reverse engineer that chip and make your own.

For my side project at work, I am now programming a pinball machine. Still wrestling getting the main matrix going. But this is going to be one FUN project....
 
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