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Irem M72 Sprite issues

opt2not

opt2not

Multi Boyz Pixeler
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Multi Boyz
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My beloved M72 multi has started displaying Sprite issues. It looks like the character and title screen sprites are all scrambled and flickering:
54227B20-F507-4011-A29E-8E118560CEC2.jpeg
12DB72A0-583E-4561-9743-4918F96F2D5E.jpeg
3F1163F8-B67A-43F9-ABC1-486F306B4827.jpeg
39C2C5DB-DE04-42A7-BD74-DA0A8AC00E81.jpeg


Anyone know what may cause this particular Sprite issue, before I start going into a deep dive on this to find out?
 
Found some shoddy pins on the multi for ROM 04. I’ll re-solder these pins and report back.

1637ABDE-473F-47CD-A7E0-197E7D37F1D3.jpeg
 
Cleaned up the solder on those pins, and I’m still getting these Sprite issues:
157E9AB6-A042-455E-8F3E-6DCBDCBB52C8.jpeg


Ram and Rom checks are OK at boot up. But these character and title screen sprites are still scrambled.

I’m really starting to suspect my multi is bad. Are there specific pins that would cause these issues that I can check continuity between?
I went over the multi multiple times to look for broken traces and couldn’t see any.
Looked for broken pins, found none. I really don’t get it.
 
Does pushing down/slightly lifting up on the connectors between all boards/the multi do anything?

I have a R-Type Leo on M92 that does very similar things and it’s the connection between the boards.
 
Apocalypse said:
Looks like an issue with address lines to me.
Click to expand...
Address lines on the multi board? (Please say yes. I really hope the mainboards are not faulty).

djsheep said:
Does pushing down/slightly lifting up on the connectors between all boards/the multi do anything?

I have a R-Type Leo on M92 that does very similar things and it’s the connection between the boards.
Click to expand...
Flex or pushing on the board does not change a thing. :(
 
I've had a similar issue, but on a lot smaller scale. I haven't really checked into it more.
 
I had a similar issue on my old Rtype pcb and it ended up being one of the rams, I beleive it was the “skinny” 6116 and was burning hot.
My issue wasn’t as pronounced but did have artifacts horizontally, I’d try feeling the around for anything hot.
PS: I’m not sure where you’re located in Cali but I’d be willing to help test your multi on my board or test my multi on yours if you’re not too far, I’m down the street from Golf N Stuff in Downey.
 
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