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Double Dragon 3 Graphics Fault

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xodaraP

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Hi guys,


I've come across a Double Dragon 3 that is stuck in inverted screen mode (I read somewhere that DD games are inverted normally, but the switch to make it "normal" is not functioning.


There is also fairly bad graphics corruption on the main title screen and during the attract mode, but the gameplay in attract mode actually seems to be mostly fine. The sprites are all good and the game plays normally enough by the look of it.


I've narrowed the graphics issue down to the top left corner of the board where the mask ROMs 30J-4, 5, 6 and 7 are - these are soldered down however so I'd like to try and narrow it down further if at all possible. I can't find any schematics for the board so in order to work out which traces are going where all 4 of these are going to have to be removed.


The test mode also does not work properly and comes up with what looks like some of the bookkeeping data when test mode is tripped.
 
I sold my DD 3, but I think your test mode is normal. For screen flip you're probably after a dip switch setting.
 
The DIP switch is switch 7 on DIP switch set 1, on or off the screen remains inverted so it's not functioning correctly :(

Also I can't get anything in test mode other than that bookkeeping data, I assumed that test mode might show this kind of data but should also be able to run RAM tests and stuff
 
Like I said if I remember right test mode is worthless and only displays the bookkeeping data. Check the dip bank with a multi meter, you should be able to see if the dip is bridging the 2 points or not.
 
A couple other quick thoughts; MAME should be good for testing the expected behaviour of test mode, and also don't trust DIP sheets you find online unless it's a scan or photo; the ones people list out are often very wrong. If I am in doubt I usually photo my board for the current settings, set all DIP's OFF, and go from there.
 
I did check the DIP switch and it's definitely making contact - the DIP switch settings were from the manual scan on the KLOV website, the DIP for test mode definitely works but it's on the other bank of switches so I'll try the other SW1 DIPs

MAME is a good idea too
 
Fired it up in MAME, you are correct and the test mode is just the bookkeeping stuff which doesn't seem to actually work. Flip screen is definitely controlled by dip 7 bank 1 and is not functioning
 
I tried that but the pins don't actually have any traces showing on either the top or the bottom of the board, so they must be on an internal layer :(
 
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