Universal Mr Do wont boot past self test

adams_arcade

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Donor 2012, 2023
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Boots up to the screen cross hatch then sits there doing nothing more...

Any suggestions? Using a Mr Do to jamma adapter on my test rig
 
Boots up to the screen cross hatch then sits there doing nothing more...

Any suggestions? Using a Mr Do to jamma adapter on my test rig

make certain that none of the buttons are being pressed when power up, this is how that machine goes into self test. Also make certain the test button is not pressed of if a slide switch. It sound to me like it is stuck in test mode.
 
I looked closer at this board and found this switch damaged. I believe it is part # E61-00A Micro Switch

Not sure if this could be creating the problem. During the switch test it is showing a "0" for Player 1 and Player 2 "Fire" This means the board thinks those buttons are bring pushed in.

Is the E61-00A just a normal micro switch like the ones we use for buttons??
 
Image attached where damage is seen
 

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Mr do' s test mode is enabled by pressing the fire button down during boot. I think that's a service/credit button. I'd just Desolder it completely

If you need a working mr do let me know. I have 1 or 2
 
I agree. The board appears the to think the fire buttons are being pushed. The question is figuring out what is sending the signal. It cant be my adapter as a different gives the same result
 
Your input buffer might be bad. It's probably a 74ls244 can check schematics when home and if you have a logic probe you can test... Even a multeter will work in this case if its constantly registering down.
 
Actually might be more than that. If I remember correctly (which might not be the case) mr do should go to another screen with text with ram ok and rom ok after the grid screen... Or maybe it's the opposite and the grid screen is last.
 
Assumiming you know that the stuck input is causing the boot issue. The schematic of the inout section should show you which I.C. is responsible for that. Simply removing the chip and it booting may be a proper diagnosis. In any case if you were not certain of what was happenning you could check the rest line and clock signals, but it sounds like you are past that.
 
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