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SEGA System2 jumpers, purpose?

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keropi View Drop Down
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    Posted: 16 May 2019 at 6:09pm
Hello!

anyone knows the purpose of these solder-jumper point on SEGA System2 boards?



I have an original Choplifter and a Wonderboy in Monster Land (cannot say for sure this is a conversion or not) and they have the jumper under IC75 different. 
Now Monster Land works correctly with both settings but I am now wondering what the correct one is...

Any ideas? thanks in advance!!! Smile
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Post Options Post Options   Thanks (0) Thanks(0)   Quote smarty Quote  Post ReplyReply Direct Link To This Post Posted: 16 May 2019 at 9:04pm
My System2 Choplifter is parched the same as your two photos. The blue wire must be a factory mod as mine has it too. They might be marked up on the Choplifter schematics as they’re on the web if you want to search for them.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote keropi Quote  Post ReplyReply Direct Link To This Post Posted: 16 May 2019 at 9:44pm
the blue wire is a factory mod so that you don't need a protection mcu for the games
this is weird because my original choplifter has the bridge on both points under IC75 ...
left of the "jamma" connector there is a silkscreen with the pcb part number, can you tell me smarty what your board has there?


Edited by keropi - 17 May 2019 at 10:40am
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Post Options Post Options   Thanks (0) Thanks(0)   Quote smarty Quote  Post ReplyReply Direct Link To This Post Posted: 17 May 2019 at 8:14pm
Sure, here's some images. I think that covers all the silkscreen and stickers on the board:









Edited by smarty - 17 May 2019 at 8:14pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote keropi Quote  Post ReplyReply Direct Link To This Post Posted: 17 May 2019 at 11:54pm
thanks!!!

it seems you have another revision ...
my boards are 171-5303-01 (choplifter, both points soldered) and 171-5305 (same as your pics) and they don't use the protection MCU 
atm I left the jumpers as they are , both boards run Monster Land just fine (after swapping ICs that is) and original Wonderboy... so maybe those jumpers are revision dependent and not roms used ... no idea :\

anyways it seems this will remain a mystery - thanks though smarty for the time spent on this!!!


Edited by keropi - 17 May 2019 at 11:55pm
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